S R Majumdar Hydraulic Pdf Download

This project describes different case studies of hydraulic failure in gold mining machines, the research was conducted to know and understand the components, construction, location, function, circuit diagram and the case studies of different failures in the hydraulic systems. The case study includes all mobile machines that are used in the gold mining site which they have different types, sizes and applications. Hydraulic system consists of a prime mover engine or electrical motor to help in driving the hydraulic pump which draws the hydraulic oil from the reservoir via filter in the suction line and delivers it to the direction control valve via relief valve in the delivery line. Work is done smoothly by converting mechanical energy into hydraulic energy and then back to mechanical energy which is used to move the hydraulic cylinder linearly or rotate the hydraulic motor. Most problems of hydraulic failure in gold mining machines on field site are caused by either contamination or climate condition (temperature). Also usage of old and outdated of machines and lack of maintenance are other factors affecting the machines performance. These problems lead to increase the down time and decrease the productivity.

Figures - uploaded by Osama Khayal

Author content

All figure content in this area was uploaded by Osama Khayal

Content may be subject to copyright.

Discover the world's research

• 20+ million members
• 135+ million publications
• 700k+ research projects

Join for free

i

   

Nile Valley University

Faculty of Post Graduate Studies

Mechanical Department

Master Degree by Research in Mechanical Engineering

Study of Failure in Hydraulic Systems

(Case study of machinery used in local gold mining)

By

Salih Adam Burma

Supervisor

Assistant professor: Osama Mohammed Elmardi

Date: September 2014



i

ACKNOWLEDGMENT

A journey is easier when you travel together. This project is the result of

one year of work whereby I have been accompanied and supported by many

people. It is a pleasant aspect that now I have opportunity to express my

gratitude for all of them. I would like to express my deep gratitude to my

supervisor assistant professor Osama Elmardi , for supporting the subject matter

when introduced to him, for his encouragement and belief in me, for the

uncountable number of hours spent sharing his knowledge and discussing

various ideas, and for many useful comments and suggestions while examining

my work. I would also like to express my thanks to faculty members of

Mechanical Engineering Department and post graduate studies, who contributed

a lot in completing and helping to finish this work in time.

I dedicated my work to my parents, and family members for their continual

support and encouragement in attaining my academic achievements. Of all

above, i would like to thank God almighty for having blessed me to carry out

my research.





















ii

 



 

















  

  





       







  





 

  





















iii

Abstract

This project describes different case studies of hydraulic failure in gold

mining machines, the research was conducted to know and understand the

components, construction, location, function, circuit diagram and the case

studies of different failures in the hydraulic systems.

The case study includes all mobile machines that are used in the gold

mining site which they have different types, sizes and applications. Hydraulic

system consists of a prime mover engine or electrical motor to help in driving

the hydraulic pump which draws the hydraulic oil from the reservoir via filter in

the suction line and delivers it to the direction control valve via relief valve in

the delivery line. Work is done smoothly by converting mechanical energy into

hydraulic energy and then back to mechanical energy which is used to move the

hydraulic cylinder linearly or rotate the hydraulic motor. Most problems of

hydraulic failure in gold mining machines on field site are caused by either

contamination or climate condition (temperature). Also usage of old and

outdated of machines and lack of maintenance are other factors affecting the

machines performance. These problems lead to increase the down time and

decrease the productivity.















iv

Table of contents

Chapter One : Introduction

1-1 Historical background

Chapter Two : Theoretical study of hydraulics

2-1 Theoretical study of hydraulic components

2-3 Basic symbols of hydraulic components

2-4 Contamination control in hydraulic systems

Chapter Three : Case studies of machinery used in local gold mining

3-1 Case study of excavators

3-2 Case study of wheel loaders

3-3 Case study of Bulldozers

3-4Case study of hydraulic hoses

-  Case study of hydraulic cylinder leaking

-  Case study of hydraulic motor failure

-Case study of transmission pump shaft Broken

-Case study of rock Drilling Machine

3-9 Case study of Dump trucks

v

-  Hydraulic Systems Safety Procedures

-  Personal Protection Equipment

-  Preventing injuries when working with hydraulic machines

Chapter Five : Discussion

Chapter Six : Conclusions & Recommendations

vi

List of Figures

Figure 1-1 Surface mining using CAT loader and CAT dump truck

Figure 1-2 Surface mining using Hitachi excavator and dump truck

Figure 1-Underground miming-using Horizontal Drilling Equipment

and cable for lighting

Figure 1- Underground miming- using Horizontal Drilling

Equipment

Figure 1-5 Underground miming-Horizontal Drilling , using dump

truck and loading Equipment

Figure 2-1 Basic components of a hydraulic circuit physically

Figure 2 -2 Excavator hydraulic components physically

Figure 2-3 The main components of a reservoir manufactures

Figure 2-4 A photograph of the main hydraulic pump& pilot pump

Figure 2-5 Types of pumps

Figure 2-6 A longitudinal section of a pressure relief valve

Figure 2-7 Pictorial view of pressure relief valve

Figure 2-8 Direction control valve operated manually

Figure 2-9 Solenoid operated control valve

Figure 2-10 Basic constituents of hydraulic hose

Figure 2-11 Hose poor design twisting and good design not twist

Figure2-12 Different sizes and types of filters(cartridge and

element)used in hydraulic circuits

Figure 2-13 Hydraulic Travel Motor

Figure 2-14 Hydraulic swing Motor

Figure 2-15 Single acting cylinder

Figure 2-16 Double acting cylinder

Figure 2-18 Different size of O-ring seals

vii

Figure 2-19 Pressure Gauges

Figure 2-20` Hydraulic accumulator

Figure 2-21 Hydraulic accumulator in brake circuit

Figure 2-2 Hydraulic oil water cooler

Figure 2-23 Hydraulic oil air cooler

Figure 2-24 Hydraulic oil cooler physically

Figure 2-25 A basic hydraulic system

Figure 2-26 Simple hydraulic circuit

Figure 2-27 Complex hydraulic circuit with hydraulic motor actuator

Figure 2-28 A different types of symbols used in hydraulic circuits

Figure 2-29 Contamination damage is apparent in the rod seal

Figure 2-30 Contamination level

Figure 2-31 Contamination level hart

Figure 2-32 Wiper seal damage caused by excessive heat

Figure 3-1 Piston rod of bucket cylinder

Figure 3-2 Excavator operating near a river bank

Figure 3-3 Excavator (pc400) excavating around a hill

Figure 3-4 Wheel loader 950F

Figure 3-5 Loader (950G) loading

Figure 3-6 Wheel loader steering cylinder

Figure 3-7 Steering system components

Figure 3-8 Hydraulic oil pressure gauge

Figure 3-9 Hydraulic oil temperature gauge

Figure 3-10 hydraulic oil cooler

Figure 3-11 Atypical bulldozer cleaning surface of mining site

Figure 3-12 Bulldozer transmission control valve

Figure 3-13 Bulldozer transmission assembly

Figure 3-14 Bulldozer transmission components

Figure 3-15 Hose damaged by abrasion

viii

Figure 3-16 Hose burst away

Figure 3-17 Hose burst at coupling

Figure 3-18 Hose O-ring seal damaged

Figure 3-19 Hose leak at threat end

Figure 3-20 Hose Coupling Blow- Off

Figure 3-23 Hose cover blisters

Figure 3-24 Hydraulic cylinder leaking

Figure 3-25 Motor pistons damaged

Figure 3-26 Motor plate damaged

Figure 3-27 Pump shaft broken

Figure 3-28 Shaft sheared and shaft twisted

Figure 3-29 FRD drilling machine which is used in surface mining

Figure 3-30 Another type of drilling machine which is used in surface

mining

Figure 3-31 Dump truck unloading

Figure 3-32 Dump truck hydraulic system components and circuit

Figure 3-33 Dump truck failed to unload

Figure 4- FLUID INJECTION INJURY

Figure 4-2 hydraulic oil injected in to human hand

Figure 4-3 Bucket damage and falling down

Photograph 1 high expensive machine for large gold industrial

Photograph 2 Old dump truck high down time low productivity-spare

parts very expensive

Photograph 3 Old dump truck high down time low productivity -spare

parts very expensive

Photograph 4Dump truck type CAT high reliablety and productivty

Photograph 5 Mining area contamination of solid particles (dust)

ix

Photograph 6 Drilling machine type FLEXIROC

Photograph 7 Large machine type TEREX high cost high productivity

used on surface mining 70 Photograph 8Haul road design and ramp

gradients; on mining site

Photograph 9 Excavator 5500 HITACHI loading Dump truck

Photograph 1o Excavator 5500 HITACHI loading Dump truck

Photograph 11 orifices and fittings

Photograph 12 Bulldozer cleaning service road to the gold mining site

Photograph 13 Surface Haulage Accidents

Photograph 14 -

sorry

Photograph 1 - Basic hydraulic components of bulldozer

Photograph 14 Tough design of excavator



















Chapter One

Introduction

-1 Historical background.

Hydraulic systems are used to transfer energy by converting mechanical

energy to fluid energy and then back to mechanical energy. The principal or

main reason for converting mechanical energy to fluid energy is the convenience

of transferring easily to a new location .The transmission and control of power

by means of fluid under pressure is used extensively in all branches of industries

and mobile equipment, lifting machines, pressing machines, drilling machines

etc.

The present thesis deals with the study of hydraulic system of equipment

used in local gold mining industry. As we all know gold mining is the process of

mining gold or gold ore from the ground by using several techniques and

processes of extraction and therefore can be classified as, surface mining and

underground mining. Surface mining entails removing vegetation, top soil, and

overburden materials above a mineral deposit and removing the deposit. In

open-pit mining, waste is transported to a disposal site, and ores are transported

to a downstream processing site. In underground mining the deposit is accessed

from the surface via vertical shafts, horizontal edits, or inclines. The deposit

itself is developed by traversing the ore body to enable human access, the

extraction of blocks of ore, the transport of ore and waste and the easiness of

ventilation. In hard-rock mines drilling and blasting techniques are used.

The main equipment used in local gold miming are wheel loader,

excavator, backhoe, bulldozer, drilling machine and dump truck ...etc. They

perform a variety of functions like preparation of ground, excavation, haulage of

material, dumping/laying in specified manner, material handling, road

construction etc. These equipments are required for both construction and

mining activities. The hydraulic systems in gold mining equipments are

typically exposed to solid particles and fluid contamination which causes a rapid



wearing and components failure. Lack of maintenance of hydraulic systems is

the leading cause of components and system failure. Yet, most maintenance

enance techniques of hydraulic systems.

If the study is focused on preventing system failure, then, less time and cost

could be saved. Maintenance is the combination of all technical and managerial

actions during the life cycle of an item intended to retain it in, or restore it to, a

state in which it can perform its required function as stated in Ref. [1]. The

maintenance of mining equipment is both challenging and expensive. Over the

years, remarkable progress has been made in maintenance equipment in the

field, but factors such as complexity, size, competition, cost, and safety continue

to challenge maintenance engineers. (Refer to Ref. [ ).

Increased mechanization, automation, and amalgamation of the processes

within mines have further complicated the issue as it is clarified in ref. [

Mining equipment maintenance costs range from  to over 35% of total

mining operating costs, and they are continuing to increase. To control these

higher value of expenses, mining companies have focused on areas such as

optimizing scheduled maintenance operations, deferring non-essential

maintenance ,reducing maintenance manpower,controlling inventories of spare

parts more effectively and using contract maintenance support as stated in

ref . They look for better maintenance practices for their mobile equipment,

especially in underground mining operations where control of maintenance costs

requires effective maintenance planning. Better control of maintenance through

team work, proper and timely accomplishment of tasks such as data recording

and reporting also play a major role in maintenance.

-2 Challengers

Machinery is fundamental to the function of mining operations .Having

high functioning equipment which is regularly maintained is a challenging factor

in the smooth running of project and increasing productivity. However, many

mining companies are using old machinery which is usually a ticking time bomb

with a history of glitches and failures. Not only is this unsafe, but the



breakdowns mean downtime while equipment is getting repaired and the time

factor required in maintenance means more money to pay. Breakdown in drives

are a regular occurrence on the mine site and can cost the business thousands of

dollars. There are a number of problems associated with existing, ageing

equipment including unreliability, where the chance of frequent failures is high

and drives up the maintenance costs, as well as inefficiency due to the long

periods of downtime. According to recent studies, 41% of open pit equipment

costs are maintenance related and maintenance can for mining companies,

represent, up to 30% of operating costs. The high cost and long turnaround time

for repairs due to unavailability of spare parts or replacements, results in high

losses of production time. With cost reduction a prominent factor in keeping

operations float, companies need to invest in initiatives around equipment that

lower unplanned maintenance and repair costs, provide quick turnaround for

part replacements decrease inventory carrying costs and reduce the risk of injury

and accidents, refer to refs.[12,13,16, . Figures ( -   - below

show surface and underground mining.

Figure 1- Surface mining using CAT loader and CAT dump truck



Figure - 2 Surface mining using Hitachi excavators and dump truck

Figure (1-3): Underground mining using Horizontal Drilling Equipment and cable for lighting



Figure (-: Underground mining using Horizontal Drilling Equipment 



Figure 1-5 Underground mining, using loading Equipment, dumptruck and Horizontal

Drilling machine.











Chapter Two

Theoretical study of hydraulics

2-1 Theoretical study of hydraulic components 

The main components of hydraulic system are, reservoir, pump, control

valve, actuators, hoses and pipes, hydraulic fluid, oil cooler ,and filters, they

must be arranged properly to perform a useful task. In this section we will study

the components of the hydraulic system. Refer to refs. , 

Figure (  - and 2-) below show the basic components of hydraulic circuit and

the hydraulic components of an excavator.

Figure:  - Basic components of hydraulic circuits



Figure 2- 2 Excavator hydraulic components

- Reservoir

Every hydraulic system includes a reservoir to supply hydraulic fluid to the

pump and to provide storage for fluid retuning from hydraulic circuit .The

reservoir must have sufficient volume to allow the returning fluid sufficient

resident time to cool and to allow air to escape before the fluid re-enters the

            be

needed .The return line is normally below fluid level in the reservoir to prevent

air entrainment and foaming of the fluid. The reservoir designer can use careful



placement of the two reservoir ports and baffles to prevent the returning fluid

from immediate entry into the pump port, otherwise the fluid would not have

time to cool .The reservoir normally operates at atmospheric pressure and thus it

is vented to the atmosphere, The reservoir will allow contaminates to settle on

the bottom and dissipate hea t. . Figure ( - below shows the main components

of atypical reservoir. (Refer to refs. [ ] ).

Figure -3 the main components of a reservoir







2- Hydraulic fluid

The most important property of hydraulic fluid is its viscosity.

Manufacturers generally recommend fluid viscosity at operating temperatures.

Oil viscosity is highly dependent on temperature, and viscosity control is

important because pump and motor efficiencies depend on it.

Functions of hydraulic fluid

Power transmission:-

This is the primary function of hydraulic oil, it is very important that

hydraulic fluid transfers power efficiently and economically.

Lubrication of all moving parts (reciprocating and rotary parts).

This is essential to reduce friction and wear, proper lubrication extends

equipment life span, and also reduce both operating and maintenance costs

Heat medium:-

If excessive heat builds up it will severely reduce the system efficiency and

may even make the system non-functional.

 Sealing medium:-

It acts as sealing medium, because whirling action of the fluid helps the

seals to function properly so as to reduce losses due to leakage. This action

optimizes the full power and the system efficiency.

Anti  Oxidant medium:-

The hydraulic fluid maintains the system in good working order, and it must

be provided with an anti- oxidant medium to preserve the system from oxidation

which leads to rusting, corrosion and erosion [ and 41]

3- Hydraulic pump:-

In any hydraulic system the pump creates flow of fluid,  

pressure but has to overcome the resistance to flow in the circuit. The re are two

basic groups of pumps, positive displacement and non-positive displacement

pump, the use of non-positive displacement in the hydraulic circuit is limited to

providing boosted supply to the main positive displacement pump. The pump is

composed of main pump and pilot pump. The main pump is a variable



displacement axial plunger pump. It provides high pressure oil for the hydraulic

system. The pilot pump is a fixed displacement gear pump; it supplies oil for the

control system. The main pump is driven by the engine through a coupler. The

pilot gear pump is connected directly by the drive shaft of the main pump at the

same rotate speed [ ] . Figure ( - ) below shows a photograph of the main

hydraulic pump and pilot pump for an excavator, and Figure ( - ) below shows

a diagram containing the different types of pumps using in hydraulic system.

Figure  -  a photograph of the main hydraulic pump and pilot pump











Figure  -  types of pumps



4- Hydraulic control valves.

Valves are used in hydraulic circuits to control pressure, volume flow rate,

and direction of flow .The most common type of pressure control valves can be

summarized in the following categories :-

I- The pressure relief valve

This is used to limit the pressure in a hydraulic circuit to a safe level. In a

hydraulic circuit in which flow is supplied by fixed displacement pump, for

example the pump may continue to produce flow even when an actuator is

stalled and incapable of accepting flow [  In the absence of a pressure

relief valve, the pressure would climb rapidly until the circuit ruptured at some

point and provided an escape path for the flow. Pressure relief valve is set to a

specific pressure at which it will open and begin to dump flow to the tank; until

system pressure reaches the cracking pressure the valve is closed. Unloading

valve is used to unload the pump when the pressure at some point in a hydraulic

circuit reaches a desired level. Figure ( - ) below shows a longitudinal section

of a pressure relief valve, and Figure ( - ) shows a pictorial view of a relief

valve.



Figure -6 a longitudinal section of a pressure relief valve



Figure  - pictorial view of pressure relief valve

II- Direction control valve (DCV)

The main control valve is located between the main pump and actuators (all

of the cylinders and motors).It is used to control the oil direction, pressure, and

flow rate for all of the actuators. It consists of valve body with passage and ports

and sliding spool, it can be operated manually (lever) or by electrical solenoid to

slide the spool to different positions, the ports, P and T provide pressure and

return, while A and B are for the connection to the actuator or circuit to be

controlled by the valve. The valve spool can be slide inside the box to align with

the ports, refs [  , and 23]. Main control valve is pilot control, open negative

flow control, and paralleling monolithic multi-ported directional valve

composed of nine spools. It includes spools for the boom, Arm, bucket swing

travel and auxiliary devices. Figure  - below shows a pictorial view of a

directional control valve which is operated manually and figure  - below

shows a solenoid operated control valve.



Figure  - Direction control valve operated manually



Figure  -  Solenoid operated control valve

5- Hydraulic lines

Hydraulic lines or conduits are used to transfer hydraulic fluid between

components. Rigid lines are made from steel, while flexible lines are made from

wire-reinforced rubber. The line must be strong enough to withstand the

maximum pressure to which it will be subjected, and large enough to convey the

hydraulic fluid without excessive pressure drop. Manufacturers of hydraulic

hoses normally specify the limiting pressure rating of their hoses.

The hose used is composed of three basic layers; an inner tube, the

reinforcement layer and the outer cover. The inner tube is made of a plastic

material and the reinforcement layer is a fabric braid which provides the

necessary strength to resist internal pressure (or external pressure in the case of

suction/vacuum). The three basic types of reinforcement are braided, spiraled

and helical.

The outer cover is a plastic cover that will resist some heat splatter such

that produced by welding. HWH hose has a heat tolerance of about (

degrees Fahrenheit, constant temperatures exceeding this can damage the hose

and create leaks especially at the hose ends.

Bubbling of the outer cover is usually an indication of a heat issue. Engine

or exhaust heat and even engine cooling systems (the engine radiator) can cause

heat issues. (Refer to [ , 56, and 67]). Figure ( - below shows the basic

components of hydraulic hose and Figure ( - ) below shows hose poor design

twisting and good design not twisting.



Figure 2-10 basic constituents of hydraulic hose.





tingtwis Movement causes -Poor design Movement flexes hose but does not twist -good design

Figure  - hose poor design twisting and good design not twist



6- Hydraulic filters

Clearances between mating parts in some hydraulic components are (

micrometer or less), and if particles of that size or larger pass between mating

parts severe damage can result. Filters are used to remove solid particles just

upstream of the reservoir return port. To prevent large particles (150 micro

meters or large) from entering the pump, a strainer or porous filter is usually

placed on the reservoir withdrawal tube. Refer to [  ]. Figure -12 below

shows different sizes of filters used in hydraulic circuits.

Figure -12 Different sizes and types of filters (cartridge and element) used

in hydraulic circuits

7- Hydraulic Actuators

A hydraulic actuator is a device used for converting hydraulic power into

mechanical power. There are two types of actuators, rotary and linear. Rotary

actuators are called hydraulic motors, while linear actuators are called hydraulic

cylinders.

1- Hydraulic motors:-

They are similar in appearance to hydraulic pumps. pumps and motors can

often be used interchangeably .The important factors that can be noted, is the

speed of hydraulic motor which is effected by , Internal leakage from the inlet

port to the out let port of the motor, volumetric efficiency of the motor and the

torque produced by the motor.



The Travel and swing motors.

Reducer consists of a hydraulic motor and a reduction gear. It is used to

control the forward, backward, left turn and right turn operation of the machine.

The travel speed can be controlled by travel speed control switch. There are two

speed positions, Low Speed and High Spe ed .

Figure  - and -14 below show a hydraulic travel and swing motors

respectively.

The travel motor is used to moves the machine forward and backward. The

swing motor and reducer which consists of a hydraulic motor and reduction

gear, is used to rotate the upper structure of the excavator, as in refs.  ].

Figure  - Hydraulic Travel Motor



Figure 2-14 Hydraulic swing Motor 



- Hydraulic cylinders

Can be divided into two main groups which are:-

i- Single acting.

ii- Double acting.

Each is used to convert the pressure energy of a fluid into a linear thrust

i- Single acting cylinder

This can be powered in one direction only (either extend or retract) by

hydraulic force, the return movement is brought about by either spring built into

the cylinder or external force.

Figure  - below shows a longitudinal section of a Single acting cylinder.

Figure -15 Single acting cylinders

ii- Double acting cylinder

This can be hydraulically powered in both directions by applying fluid

pressure to the appropriate side of the piston. Figure ( - ) below shows a

longitudinal section of a double acting cylinder. Refer to ref. 

Figure -16 double acting cylinders 



- Hydraulic orifice

In hydraulic circuit design it is often necessary to restrict flow to some

segment of the circuit and/or to create a pressure difference; this goal can be

achieved by using a hydraulic orifice. Many valves form orifices that are used to

control flow of the fluid. Figure ( - ) below shows a hydraulic orifice.

Figure -17 orifices

9- O-ring Kit seal

Elastomeric O-rings are unlike most of the materials that engineers and

designers encounter. The reason, O-rings must deform to function properly. As

the name implies, O-rings are shaped like a donut. (Torus is the geometric term.)

They are installed in cavities known as glands and then compressed. The

resulting zero clearance within the gland provides the seal that blocks the flow

of liquids and gases. This simple arrangement serves many fluid-power systems

very well, but O-rings are the most commonly used seals in fluid-power

systems. However, success still requires careful design, selection, and

installation procedures. O-rings typically fail in their applications because of the

combined adverse effects of several environmental factors. Figure (2-18): Below

shows different sizes of o- rings. (Refs. [ ])

Figure -18 Different sizes of O-rings seal



- Pressure Gauges and Volume Meters

Pressure gauges are used in liquid-powered systems to measure pressure so

as to maintain efficient and safe operating levels. Pressure is measured in psi or

bar. Flow measurement may be expressed in units of rate of flow meter cubic

per second (cms). It may also be expressed in terms of total quantity-gallons or

cubic feet.

1- Pressure Gauges.

Figure ( - shows a simple pressure gauge. Gauge readings indicate the

fluid pressure set up by an opposition of forces within a system. Atmospheric

pressure is negligible because its action at one place is balanced by its equal

action at another place in a system.

- Volume Meters.

Measuring flow depends on the quantities, flow rates, and types of liquid

involved. All liquid meters (flow meters) are made to measure specific liquids

and must be used only for the purpose for which they were made. Each meter is

tested and calibrated. (Ref. []) .

Figure -19 Pressure Gauges

- Hydraulic accumulators

An inert gas above the diaphragm is compressed when hydraulic fluid is

forced into the space below the diaphragm. The compressed gas represents

potential energy that can be reconverted into hydraulic energy when needed.



Because the compressed gas provides cushioning, an accumulator can also

be used as shock absorber to reduce maximum stresses when the system is

subjected to unusual loads. Figure  - and 2-21 below show a sectional view of

a hydraulic accumulator and hydraulic accumulator in brake circuit , [ ].

Figure 2- Hydraulic accumulators



Figure -21 Hydraulic accumulators in brake system.



- Hydraulic oil cooler

If reservoir volume is too small to allow sufficient cooling of the hydraulic

fluid, oil cooler may be used; typically the oil cooler is a liquid to liquid heat

exchanger that transfers heat from the hydraulic fluid to the engine coolant.

Figures 2-22 and 2-23 below show a hydraulic water and air coolers and Figure

-  Below shows hydraulic oil cooler physically, the arrow shows water flow

and full(black) arrow shows oil flow, and it's location on the symbol hydraulic

circuit.( Refs. [ ]).

Figure  -  hydraulic water coolers

Figure  -  Hydraulic air cooler



Figure 2-24 physical representation of hydraulic oil cooler

- Circuit Diagrams

1- Hydraulic circuit and components

Figure ( - : Below depicts a basic hydraulic system. For a basic

hydraulic system to operate (e.g. cylinder extend and retract), it must contain the

following components.

 Fluid (A)

 Reservoir (B)

 Filter (C)

 Pump (D)

 Direction control valve (E)

 Actuator or hydraulic cylinder (F)

 Lines (G)

 Pressure control valve (H)

 Cooler (I)

Most manufacturers use graphic symbol circuits to identify the circuit

components, and to illustrate the circuit function and operation.( Ref. [ ).



Figure -25 basic hydraulic system components



- Complete Hydraulic Schematic representation:-

Here we have a simple hydraulic schematic using the symbols that are

shown below. You can see that we have a hydraulic pump which gets its fluid

from the reservoir, pulls the fluid through the filter then sends it to the valve.

The direction control valve directs the oil to the hydraulic cylinder or to the

hydraulic motor. Figure 2-26 and 2-27 below show simple and complex

hydraulic circuits. Figure 2- illustrates the components of simple circuit which

are reservoir, filter, pump, relief valve, direction control valve, cylinder

respectively. In Figure -  the components of a complex circuit are shown

and they consists of reservoir, filter, pump, relief valve, direction control valve,

and motor respectively by using hydraulic symbols. Refer to refs,].







Figure -26 simple hydraulic circuit



Figure -  Complex hydraulic circuit



2.3 Basic symbols of hydraulic components.

A schematic diagram is a line drawing composed of hydraulic symbols that

indicate the types of components which the hydraulic circuit contains and how

they are interconnected.

A schematic diagram is a road map of hydraulic system and to a technician

skilled in reading and interpreting hydraulic symbols , is a valuable aid in

identifying possible causes of problems and therefore can save a lot of money

when trouble shooting problems, refer to refs. [  Figure -28 below shows

different types of symbols used in hydraulic circuits.



Figure -28 Types of symbols used in hydraulic circuits.



-  Contamination control in hydraulic systems

Figure  - below shows a contamination damage which is apparent in the

rod seal. Figures -30 and 2-31 show a contamination level and chart of a

components contamination level.

Contamination Control in a hydraulic system is a very wide and complex matter;

the following is just a short summary. The function of the fluid in the hydraulic

systems is transmitting forces and motion. In view of a reliable and efficient

operation of the system, it is very important to select the fluid considering the

requirements of the system and the specific working conditions (working

pressure, environment temperature, location of the system, etc.).Depending on

the required features (viscosity, lubricant capacity, anti-wear protection, density,

resistance to ageing and to thermal variances, materials compatibility, etc.), the

proper oil can be selected among a number of mineral oils (the most popular),



synthetic fluids, water based fluids, environmental friendly fluids, etc. All the

hydraulic fluids are classified according to international standards.

Solid contamination is recognized as the main reason for malfunction,

failures and early decay in hydraulic systems; it is impossible to be eliminated

completely, but it can be well kept under control with proper devices (filters).

No matter which fluid is used, it must be kept at the contamination level

required by the most sensitive component used on the system. The

contamination level is measured by counting the number of particles of a certain

dimension per unit of volume of the fluid; this number is then classified in

Contamination Classes, according to international standards. Measuring is made

with Automatic Particle Counters that can make the analysis on line (through

sampling connectors put on the system for this purpose) or from sampling

bottles. The calculations and sampling of the fluid must be done according to the

specific ISO norms, to attest their validity. The most popular standard for

Contamination Classes in the hydraulic systems is ISO 4406:1999.

i- Sources of Hydraulic System Contamination.

New oil out of shipping containers is usually contaminated to a level above

what is acceptable for most hydraulic systems. Never assume your oil is clean

until it has been filtered. There are a surprising number of different sources of

system contamination in hydraulic filtration which could be cited below:-

- Most new fluid is not acceptable for use in hydraulic systems and must be

filtered first.

- Particles introduced during normal maintenance or system operation.

- Wear generation contamination caused by the pump, actuators, cylinder or the

hydraulic motor rubber.

- Degradation of rubber compounds and elastomers products.

- Failure to thoroughly clean conductor lines after replacing a failed pump.

Clean conductor lines after replacing a failed pump.

ii- Types of Contaminant.



Many different types of contamination may be present in hydraulic fluid.

Contaminants grind and wear at the surface of moving parts, introducing even

more particles into the system. These surface degradation contaminants cause

more than 70%of all hydraulic system downtime.

Particulate ingresses, and built-in (dust, dirt, sand, rust fibers,

elastomers, paint chips) Wear metals, silicon, and excessive additives

(aluminum  chromium, copper ,iron, lead, tin, silicon, sodium, zinc, barium,

phosphorous) - water sealant (tape, pastes - sludge, oxidation, and other

corrosion products - acids and other chemicals. all these above can be source of

contamination from the hydraulic components.( Refs. [ ]).

Figure -  Contamination damage is apparent in this rod seal, where the

serrations are worn completely away. The seal on the right is a new one,

shown for comparison.



Amount of contamination in 100 gallons hydraulic oil

Donaldson Standard New, Unfiltered

Hydraulic Filter Hydraulic Filter Hydraulic Oil

ISO 14/9/3 ISO 19/17/14 ISO 22/21/18 . gram dust .363 gram dust 4.73 grams dust Figure -  show contamination level

Contamination Levels of Different ISO4406Codes Vary Dramatically.

New unfiltered hydraulic oil can contain 100 times more contaminant than oil

that has passed through filter media. Protect your hydraulic system from costly

repairs and downtime with filter media technology designed to meet equipment

filtration requirements and strength needs. (Refs. [ ] and ).





Figure  - chart of component contamination level



-  Temperature

The operating temperature is one of the factors governing the efficiency of

a hydraulic system. Where the temperature of the hydraulic fluid depends on.

- The power losses.

- The place of installation.

- The surface area of heat radiating components (such as tank) and the

maximum permitted fluid temperature depends on:-

-The type of fluid.

-The requirements of the system.

If the temperature is too low, the flow resistance is increased and

difficulties are experienced with the suction of the pump. If the temperature is

too high, there are more fluid leaks so losses and wear are greater. A hydraulic

system that could operate at constant temperature, including start-up, would

function at optimum efficiency at all times if the proper fluid viscosity had been

selected. Unfortunately, such a hydraulic system is purely theoretical because a

typical hydraulic system converts about 20%of its input horsepower into heat.

Heat in the hydraulic system may be caused by two things-friction and external

temperature. As the result of losses arising from transmission in the hydraulic

components, the temperature of hydraulic fluid rises when passing through the

system. In addition to additional cooling system, the tank itself also emits a large

proportion of heat through the surface in surrounding area. The radiated power

of heat primary depends on the size of those areas in contact with the

surrounding, and the temperature difference between the hydraulic oil and

surrounding area, when designing the hydraulic tank a designer should properly

form the tank in order to increase the size of area through which heat is emitted,

so as to provide better natural cooling. Figure  - , below shows wiper seal

damage caused by excessive heat. (Refs. []).







Figure 2-32 wiper seal damage caused by excessive heat 



Chapter Three

Case Study of Machinery Used In Local Gold Mining

This chapter discusses case study of hydraulic failure in gold mining

machines, besides identifying major causes of equipment breakdown, analyzing

the problem and finding the root causes of failure.

Hydraulic failure studies are field performance assessments that include

broad-based surveys of the hydraulic failure for a large number of mobile

equipment on-site systems.

As mentioned in chapter one the main mobile equipment used in local gold

mining areas are excavators, wheel loaders, Bulldozers ,and Rock drilling

machines, and Dump trucks, and backhoe .. ..etc.

-  Case study of excavators:-

- Case study of an excavator (HITACHI type)

Problem:-

Boom lifting power and speed are normal but bucket tilt-back power or speed

is abnormal.

Analysis and Solution:-

All probable causes are checked out but finally it is found that the failure is

of damaged seals of piston rod of the bucket cylinder which in turn causes

internal leakage. This failure occurs due to different reasons including the

contamination of the hydraulic oil and misusing the correct type of seals,

therefore these problems must be avoided in future maintenance operations.

Figures ( - ) and ( - ) below show piston rod of a bucket cylinder and an

excavator operating near a river bank. (Ref. [ ).



Figures -1 piston rod of bucket cylinder

Figures 3-2 Excavator operating near a river bank



- Case study of an excavator (komatsu pc 400 type):-

Problem:-

Figure ( - ) below shows an excavator (pc-400). The problem associated

with this excavator is that its hydraulic motor is not functioning well. The motor

has been replaced twice by another one, but the working life is less than three

weeks.

Analysis and Solution:-

It is found that most of motor components were worn out and therefore they

were replaced, but the root cause of failure is not defined .Therefore, another

check had been made and the cause of failure was found to be a blockage on the

drain line of the motor.

Figure  - Excavator excavating around a hill





-2 Case study of wheel loaders:-

- Case study of a wheel loader 950F.

Problem:-

Figures  - below shows a wheel loader 950F .The problem associated

with this loader is that its hydraulic pump is not functioning well. The pump has

been replaced by another one before completing its expected service life which

is estimated to be 10,000 hours. The pump only serviced 2000 hours which is

one fifth of its expected life time.

Analysis and solution:-

The analysis reveals that the hydraulic pump has not actually failed. The

defect is caused by excessive oil contamination.

This defect leads to the increase of maintenance costs, and the reduction of

equipment availability. The contaminants of the hydraulic oil, includes solid

particles, water, air, or any other matter that impairs the function of the oil

particle, the contamination also accelerates wear of hydraulic components. The

rate at which damage occurs is dependent on the internal clearance of the

components within the system, the size and the quantity of the particles present

in the fluid and the system pressure. The type of failure described above is

Unusual in properly designed hydraulic systems that are correctly maintained,

this highlights the importance of monitoring hydraulic fluid cleanliness levels at

regular intervals. As in this case, if the high levels of silt particles present in the

hydraulic fluid had been identified and the problem rectified early enough, the

damage of this hydraulic pump and significant expense of its repair could have

been avoided. (Refs. [ ])





Figures -4 Wheel loader F

- Case study of a wheel loader 950G.

Figure 3-5 below shows a wheel loader (950G).

Problem:-

The problem associated with this loader is that its transmission oil level is

too high, above the full mark of the dipstick.

Solution and analysis:-

The above problem is caused by leaked hydraulic oil into the transmission

oil pan causing over filling. All the probable causes are checked out but finally it

is found that this failure is due to damaged seals of the hydraulic pump shaft.

The seal of the transmission pump shaft has been replaced but the problem is

still not eliminated. The hydraulic pump has been removed for the second times,

the hydraulic pump is removed from the machine and checked up again, the new

shaft seal of the pump was damage, replaced, and installed again then the

problem is eliminated. Maintenance personnel don't used proper maintenance



technique to install the new seal; therefore the seal is damaged during

installation. This poor technique of the maintenance personnel, increase the

down time of the machine, and decrease the productivity, cost of maintenance

cost of spare part and hydraulic oil. This failure could be avoided if the

maintenance personnel used proper technique of installing the shaft seal. (Ref.

[ ).

Figure  - wheel loader 950G- loading dump truck

- Case study of a wheel loader 966C (steering system)

This case study considers closed-center, full time hydrostatic power

steering systems using two double-acting cylinders with a variable piston pump.

The first problem:-

Figure  - and 3-7 below show a wheel loader and steering system

components. The problem associated with this loader is that its Steering wheel is

heavy when turned in either direction (left or right).



Analysis and Solution:-

The following checks have been done:-

- The oil level and types of oil in the hydraulic tank is found to be correct.

- The steering wheel column is checked for abnormality.

- The hydraulic hoses, valves, or cylinders are checked for leakage.

- There is no any scuffing in the center hinge pin bearing and steering

cylinder pin or bushing.

- Tire inflation pressure is checked. After checking the above five expected

problems, it found that the defect is inside the steering cylinder (piston

seals are damaged) causes internal leakage. Therefore this problem must

be avoided in future by regular maintenance and immediate remedy.

Figure -6 wheel loader 966C - steering cylinder



Figure  - steering system components.

Figure 3- above shows the construction of steering system [ , hydraulic

circuit which consists of many components but the main components is:-

1-Hydraulic tank...............................................................................................

2-Hydraulic cylinders.............................. 

3-Hydraulic hoses

4-Steering wheel....................................................................................

5-Steering column....................................

6-Steering valve............................................. 

-Control valve....................................... ....... 

8-Steering pump................................................

9-Cross over relief valve.......................................



The second problem:-

The pressure rises in the hydraulic system (pressure gauge pointer above

the specified limits) when operating the loader not more than half an hour

continuously.

Analysis and Solution:-

After checking all expected problems, it is found that the defect is cause by

clogged hydraulic oil filter in the return line. Therefore this problem must be

avoided in future by following the regular preventive maintenance of changing

the hydraulic oil filter within the recommended period. Figure  - below shows

a hydraulic oil pressure gauge.

Figure - 8 Hydraulic oil pressure gauge

The Third Problem:-

The same loader has another problem which is:-

The temperature rises in the hydraulic system (temperature gauge pointer

reaches the red zone) when operating the loader not more than half an hour

continuously.

Analysis and Solution:-

For the hydraulic temperature rising or overheating, all the probable causes

associated with this problem have been checked, but finally it is found that the

hydraulic oil cooler is clogged. Therefore, this problem must be avoided in

future by regular cleaning the outside surface of the cooler to allow air to pass



through it to dissipate the heat, and or any other source which can cause this

defect must be checked first and eliminated.

Figure -9 below shows hydraulic oil temperature gauge and Figure 3-10

shows hydraulic oil cooler which is clogged [ ].

Figure 3-9 Hydraulic oil temperature gauges 

Figure 3-10 hydraulic oil cooler.

-  Case study of bulldozers:-

Case study of bulldozer type D and R.

Figures -11 below shows a bulldozer which is an excellent machine for

land cleanings. Cleaning operations are always preferable and usually necessary

before undertaking earth moving operation.

Figure 3-12 below shows the bulldozer transmission control valve, body, spools

and hydraulic circuit.



The first problem:-

Machine does not start travel in any transmission range.

Analysis and Solution:-

The flowing checks have been done:-

1-The pump pressure must be within the specified limit

2-The torque converter must be in a good co ndition

3-The validity of the transmission components

After checking the above three expected problems, it is found that the

transmission control valve is defected. Therefore it is replaced, and hence the

problem is solved completely.

Transmission control valve consists of a body and spools. when these

components wear, they causes excessive clearance between the control spools

and the body, which allow oil to pass in between and therefore, affects its

function.

The root causes of this problem are:-

1-The oil viscosity is too low

2-The oil is contaminated

Figure 3-11 A typical bulldozer cleaning surface mining site



Figure 3- Bulldozer transmission control valve

The second problem:-

Machine hesitation or slipping during the travel in any transmission range.

Analysis and Solution:-

The flowing checks have been done.

- Linage out of adjustment

- Linage not free

- Low fluid level

- Wrong oil used

- Incorrect pressure settings

After checking the above five expected problems, it is found that the defect

is caused by transmission plates and discs which are wearing out. Therefore, it is

replaced, and hence the problem is solved completely.

Before opening the transmission to repair two other checking confirm the above

problem.



- It is found that high level of copper (Cu), iron (Fe), and lead (Pb) in the

transmission oil which indicate that abnormal wear of the bronze friction

discs and steel separator plate.

- Cut open the transmission oil filter which has large particles of above

materials.

When these components wear out, they cause excessive clearance, which

do not allow it to transmit the full power and therefore, affect its function.

The root causes of this problem are:-

- Lag of preventive maintenance

- Wrong oil used

Figure 3- below shows a typical bulldozer transmission and Figure 3-

shows the different components of the transmission. (Refs. [  ]).

Figure 3-13 Bulldozer transmission assembly



Figure 3-14 bulldozer transmission components

-  Case studies of hydraulic hoses:-

Hydraulic hoses are flexible joint used to carry and transmit hydraulic oil to

the different components of the system.

The first Problem:-

Figure  - below shows a damaged hose due to abrasion

Analysis and Solution:-

The analysis reveals that the hydraulic hose has not actually completed its

life time. The defect is caused by abrasion, therefore these problems must be

avoided in future maintenance operations by reroute the hose to keep it away

from abrasive sources or guard the hose with a protective sleeve.



Figure -15 hose damaged by abrasion

The second Problem:-

Hose Burst Away

Figure  - below shows hose damaged by bursting away.

Analysis and Solution:-

The analysis reveals that the hydraulic hose has not actually completed its

life time. Therefore these problems must be avoided in future by the following:-

The operating pressure should be within the specified range.

- Rerouting the hose to prevent excessive flexing or keep the hose from

exceeding its maximum bend radius.

Figure -16 hose burst away



The Third Problem:-

Figure  - below shows hose burst at coupling.

Analysis and Solution:-

The analysis reveals that the hydraulic hose has not actually completed its

life time.

This problem is attributed to the following factors:-

- Weak hose assembly to accommodate contraction under pressure.

-The hose bend radius is mall and/or there is no bend restrict ors.

To solve this problem the hose assembly should be replaced with a properly

crimped assembly, so as to avoid this problem in the future.

Figure -17 hose burst coupling

The fourth problem:-

Figure  - below shows hose leaks at thread end caused by damage of

O-ring seal.

Analysis and Solution:-

The analysis reveals that the hydraulic hose has not actually completed its

life time. The defect is caused by damage of O-ring seal; therefore these

problems must be avoided in future.

The problem causes are:-

- Certain couplings require the use of an O-

O-ring is used, check for damage caused during installation or possible



material breakdown from heat or fluid incompatibility. Alternative O-ring

materials may be required.

- Check the threads and/or seat angle on both mating surfaces for damage that

may have occurred prior to or during installation. Any ding or burr may be a

potential leak path.



Figure  - O-ring seal damaged

- If the coupling was misaligned during installation, threads may have been

damaged. Replace and carefully install.

- It is possible to thread together some components that are not compatible.

Use Gates thread I.D. kit to assist in identifying mating components. Some

thread end configurations have better seal ability than others. Also, ensure

proper coupling selection.

- Over-torque of a threaded connection can damage threads and mating seat

angles. Over-torque can also damage the staking area of the nut causing

cracking of either the nut or seat. Under-torque does not allow proper sealing.

Use of a torque wrench can alleviate such problems.



Figure -19 hose leak at thread end

The Fifth Problem:-

Figure  - below shows hose coupling blow -off

Analysis and Solution:-

The analysis reveals that the hydraulic hose has not actually completed its

life time. The defect is caused by Coupling Blow Off therefore this problems

must be avoided in future by striking to the following procedures:-

- Select proper crimping pressure.

2- Examine and replace the hos assembly to ensure proper assembly procedures.

3- Modify hose length and/or routing to accommodate potential hose length

reduction under pressure.

- 

Figure  -  hose Coupling Blow- Off



The Sixth Problem:-

Figure  - below shows hose cracked.

Analysis and Solution:-

The analysis reveals that the hydraulic hose has not actually completed its

life time. The defect is caused by cracks, therefore these problems must be

avoided in future by sticking to the following procedures:-

- Select a hose that meets the temperature and flow requirements of the

application.

- Identify the heat source and consider rerouting it away from the source to

minimize the effects.

- Examine reservoir size (if necessary).

Figure -21 Hose Cracks

The seventh problem:-

Figure  - below shows damaged hose caused by twisting .

Analysis and Solution:

The analysis reveals that the hydraulic hose has not actually completed its

life time. The defect is caused by twist, therefore these problems must be

avoided in future maintenance operations through the following procedures:-

1- Replace and reroute the hose to ensure that bending occurs only in one plane.

2- The use of bent tube or block style couplings and adapters may improve

routing.

3- When installing the assembly, hold the backup hex to prevent it from turning

and applying a twist.



- If male and female couplings are used on the same hose assembly install the

male (non-swivel) end first.

Figure  -  Hose Twist

The Eighth Problem:-

Figure -  below shows hose damaged caused by hose cover blisters.

Analysis and Solution:-

The analysis reveals that the hydraulic hose has not actually completed its

life time. The defect is caused by cover blisters. Therefore these problems must

be avoided in future maintenance operations by sticking to the following steps:-

1- Replace the hose with one that is recommended as compatible with the fluid

being used.

2- If it is compressed gas, the cover can also be perforated (pin-pricked) to allow

the gas to seep through the cover.

3- Textile hose covers eliminate blistering.

- Bleed the system to eliminate any trapped air.



Figure-23 Hose cover blisters 



-  Case study of hydraulic cylinder leaking

Problem:-

Figure  - below shows hydraulic cylinder rod seal is damaged. The

problem associated with this hydraulic cylinder is that its rod seal is leaking and

has been replaced with another one but still leaking.

Analysis and solution:-

The analysis reveals that the rod seal has not actually completed its life

time. The defect is caused by the bended cylinder rod. Therefore these problems

must be avoided in future maintenance operations, by checking, the root causes

of this failure. Bend rods are common cause of rod seal failure, bending of

cylinder rods can be caused by insufficient rod diameter, material strength or

improper cylinder mounting arrangement or combination of all three.

(Misalignment could cause the seal to wear). Rod straightness should always be

checked when hydraulic cylinders are being re sealed or repaired. This is done

by placing the rod on rollers and measuring run-out with dial gauge. (Refs. [ 

)

Figure - Hydraulic cylinders leaking



-6 Case Study of Hydraulic motor Failure

Problem:-

The hydraulic motor is damaged

Figure  - and Figure -26 below show hydraulic motor failure.

Analysis and Solution:

Two piston hydraulic motors had failed well short of their expected service

life. The inspection reveals that the defect is caused by using low oil viscosity

resulting in adequate lubrication. Therefore these problems must be avoided in

future maintenance operations, by using recommended hydraulic oil, as the

temperature of the oil increases, its viscosity decreases, if the oil temperature

increases to a point where viscosity falls below the level required to maintain a

lubricating film between the internal parts of the components , wear and damage

will result. It is important not to allow oil temperature to exceed the point at

which viscosity falls below the optimum level for the system components.

Whenever a hydraulic system starts to overheat, the system must be shut down,

so as to find the cause of the problem and try to fix it. (Refs. [ ]).

Figure -25 motor pistons damaged



Figure - motor plate damaged

-7 Case study of transmission pump shaft Broken.

Problem:-

The transmission pump shaft was Broken

Figure -27 and Figure  - below show transmission pump shaft Broken. As

soon as the pump is dismounted from the machine, it is found that the shaft has

been broken and replaced by another one before completing its expected service

life.

Analysis and Solution:-

Below are the most common causes of pump shaft failure which are

checked out:-

1- Relief valve fails to function, which produces one extreme surge and

immediately failure occurs.

2- The relief valve setting is too high, which results in repeated pressure peaks,

damage the pump shaft.

After checking the above two expected problems, it is found that the suction

strainer is completely clogged. Therefore it is replaced by another one, and

hence the problem is solved completely. The analysis reveals that when the

prime mover turns the pump shaft while the strainer filter in the suction line is



clogged .The pump will be subject to two opposed forces which cause the pump

shaft to shear or torsion and result in broken pump shaft Therefore, this

problems must be avoided in future maintenance operations by replacing the

strainer filter regularly. (Refs. [ ).

Figure -27 pump shaft broken

Figure -28 shaft sheared and shaft twisted.



-  Case study of Rock Drilling Machine:-

Drilling rigs are machines that create holes (bore holes) in the ground.

They are equipped with deck engines or truck engines, compressors..

Figure -29 and Figure  - 0 below show drilling machine which is used mainly

in surface mining.

Problem:-

Levers of the control valve are heavy during operation which causes the

system malfunction.

Analysis and Solution:-

All probable causes are checked but finally it is found that the failure is due

to control valve spools sticking. The analysis reveals that the spool has not

actually completed its life time. The defect occurred due to the contamination of

solid particles which fill the clearance between main control valve body a nd

spool. Therefore this problem must be avoided in future maintenance operations,

by replacing the dust protector seal when damaged. (Refs. []).

Figure -29 FRD drilling machine which is used in surface mining  



[

Figure -30 another type of drilling machine which is used in surface mining

-  Case study of Dump Truck (body condition):-

Dump truck type HINO ZS is important machinery in mining construction

sector which is used to pick up and deliver loads of materials on site.

First Problem:-

The dump truck is raised slowly when unloading.

Figure  - below shows a dump truck.

The problem associated with this truck is that its control valve is not functioning

well.

Analysis and Solution:-

The following checks have been done:-

The hydraulic pump output pressure is found equal to 172 bars

1- The output pressure within the specified limit

- No pump cavitation

- The body hydraulic cylinder is found to be in a good condition.

4- The relief valve setting is within the specified limit. No dirt, no foreign

particles. After checking the above four expected problems, it is found that the



spool valve travel is not complete. The pin of the spool linkage push wears and

therefore causing excessive backlash. To solve the problem the pin and push

must be replaced. (Refs. [ ).

Figure -31 Dump truck HINO ZS- unloading



Figure -32 below shows the dump truck hydraulic components

filter Engine pump cylinder direction control valve pilot valve

Figure - Dump truck hydraulic components. 



Dump truck hydraulic system components and circuit of the body hoist. The

components are:-

Reservoir, pump, control valve, cylinder, pilot valve which operate the cylinder,

filter. (Refs. [ ).

The second Problem:-

The dump truck is raised but not hold on the body during unloading. Figure

- below shows a dump truck of Nissan UD . The problem associated with

this truck is that its hydraulic cylinder was leaking.

Analysis and Solution:-

All probable causes which leads to this problem are checked out but finally

it is found that the failure is of damaged seals of the piston of hydraulic cylinder.

This failure occurs due to different reasons which include the contamination of

the hydraulic oil, misusing the correct type of seals, types of oil used and

temperature. Therefore and due to the seal damage the oil by passes between

body cylinder and a piston seal (internal leaks) which causes the body not hold

on. (Refs. [ ]).

Figure 3-dump truck Nissan UD- failed to unload



Chapter Four

Safety

-  Risks

The risks of working with pressure systems of any type are well

documented and respected by those involved in work that brings them into

contact with pressure systems. Comprehensive risk mitigation and safe working

practices are drafted and adhered to by the vast majority of responsible

commercial organizations and professional technicians working with pressure

systems and equipment as part of their routine work process. A common aspect

of risk mitigation when working with pressure systems is, where possible, to use

hydraulic power in preference to pneumatic power. In some instances however,

such as lifting, cutting and pressing applications, hydraulic power is the

preferred and often the only choice. Viewed as the safe option for pressurized

equipment, the risk mitigation process can often end with the choice of

hydraulic over pneumatic power. A common risk to all hydraulic systems,

irrespective of volume, is hydraulic injection injury. This often overlooked mode

of injury can and has resulted in the loss of limb function, amputation and in

some cases, death. Although the reported instances of injury through hydraulic

injection are comparatively rare in the UK, the potential severity of the

consequences to the injured party dictate that understanding, acknowledging and

mitigating the risk of injury through hydraulic injection, is essential for any

individual or commercial organization utilizing hydraulic systems or equipment.

Although the more serious instances of hydraulic injection injuries occur at

higher pressures, anecdotal evidence suggest that injection can occur at

pressures as low as seven bars. Hydraulic injection injury occurs when a jet of

fluid under pressure penetrates the skin of an individual, most commonly the

hand or the digits of the hand. An individual may come into contact with a

pressurized jet of fluid due to the nature of the equipment they are using, such as



paint spraying equipment, or when an equipment failure occurs. Types of failure

in hydraulic equipment can be broadly categorized as:

  failure, where the piece of equipment stops working completely

following catastrophic component failure.

 Material failure, where a small leak has occurred but the equipment remains

operational.

Examples of material failure in hydraulic equipment are fatigue cracking in

high pressure fuel lines, pin holing in hydraulic hoses, seal failure and bulk

material cracking. While both modes cracking. While both modes of failure can

result in injection injury Figure 4-1 below shows fluid injection injury it is

perhaps the latter that presents the greater risk to an operator in relation to

sustaining a hydraulic injection injury. This is due to the fact that a piece of

hydraulic equipment may remain pressurized and in use while ejecting a

pressurized jet of fluid. An individual may sustain an injection injury by being in

direct contact with a piece of equipment when a failure occurs, by using

equipment with an existing failure, or while inspecting a piece of pressurized

equipment following a reduction in performance due to a material failure. The

tests carried out as part of this research suggested that the smaller the jet, such as

those associated with pin holing, the more likely the chance of injection

occurring. Figure 4- below shows hydraulic oil injected into human hand, as in

refs. [ ].

Figure  -  Fluid Injection Injury



Figure - hydraulic oil injected into human hand

-  Hydraulic Systems Safety Procedures

Hydraulic systems operate under very high pressures. Shut the system

down and relieve system pressure before opening any part of the system that is

under pressure. Do not allow spray from any high pressure leak to contact any

part of the body, as serious injection injuries may result. Pumps, valves and

motor may become hot; be cautious of incidental contact between bare skin and

hot surfaces. Keep hands and clothing away from moving parts of the system.

-  Personal Protection Equipment

Safety glasses need to be worn at all times when working on a hydraulic

system. This is to protect eyes from dirt, metal chips, high pressure fluid leaks,

etc. Additional personal protection equipment should be worn in accordance

with OSHA or local government requirements.

-  Preventing injuries when working with hydraulic machines (excavator

backhoe)

Swinging arms, booms, rollers, presses and anything that moves can be

dangerous if a hose fails. For example, when a hose bursts, objects supported by

fluid pressure may fall, and vehicles or machines may lose their brakes. Figure

4-3 below show an excavator bucket damages and falling down. (Refs.

).



Figure -3 excavator bucket damage and falling down



Chapter Five

Discussion

How to get thousands of hours in extra service life from your hydraulic

equipment, eliminate unnecessary breakdowns, reduce unscheduled downtime

and slash thousands of dollars off your operating costs.

Dear Hydraulic Equipment User, Hydraulic components are expensive,

right? So wh

line. If you're an owner-operator, it hurts your wallet directly. If you're a

manager or supervisor, it hurts your budget - and maybe even your performance

bonus. But the fact is more than 70% of spare parts sold for hydraulic equipment

are replacements for defective components. I also discovered that the reason for

90% of these defects is improper maintenance. So when you understand just

how big the spare parts business is, you know that poor maintenance practices

are costing hydraulic equipment users billions of dollars every year. If modern

hydraulic components are installed and maintained properly, the spare parts

business wouldn't be viable.

For as long as there are hydraulic equipment owners, mechanics and

maintenance people out there who believe that hydraulic equipment doesn't

require any special kind of attention, this vicious circle will continue. Over the

past 30 years, the performance, sophistication and operating pressures of

hydraulic equipment have increased significantly. This is particularly true in the

case of mobile hydraulic equipment. As a result, modern hydraulic equipment is

not only more expensive to fix when it breaks, proactive maintenance is

imperative to maximize service life and minimize operating costs. It's not

realistic to expect to run a hydraulic machine for 10,000 hours, without checking

anything more than the oil level, and not have any problems.

Machinery is fundamental to the function of mining operations. Havi ng

high functioning equipment which is regularly maintained is a large factor in the

smooth running of a project and increasing productivity. However, many mining



companies are using old machinery which is usually a ticking time bomb with a

history of glitches and failures. Not only is this unsafe, but the breakdowns

mean downtime while equipment is getting repaired and time means money, so

the result is revenue loss. Breakdowns in drives are a regular occurrence on the

mine site and can cost the business thousands of dollars.

There are additional financial implications that come with using dated

equipment as companies face excessive on-site inventory requirements,

particularly due to the necessity of (custom made) spare parts. Depending on

availability, obtaining the parts can take a long time and cost the operation a lot

of money.

In this thesis, the main problems related to hydraulic machines in local gold

mining as those associated with the contamination of oil used, the dusty

environment of the mining sites, the effects of temperature and overheating

could be solved easily with proper preventive maintenance by sticking to

manufacturer recommendation. The replacement of parts should be done

properly and in time. (Refs. []).



Chapter Six

Conclusions & Recommendations

- Conclusions

In this thesis case studies of hydraulic failure of different types of

equipments that are pertinent to gold mining area have been described, analyzed

and solved.

As with all cases study techniques, knowledge of components and their

function in a system is vitally important. It is probably fair to say that, when all

the components of a hydraulic system have been identified, their function

determined and the operation of the system as a Whole understood, the case

study has gone 51% of the way towards finding the problem. Hydraulic systems

are getting more and more complex as methods of controlling machines become

increasingly developed.

Mobile mining equipment often operates in harsh environments

characterized by remote locations and highly variable rock and operating

conditions. This research explores the hypothesis that the failure behavior of

mining equipment is influenced by the physical properties of the ore and waste.

Most hydraulic system failures in gold mining machine result from

contamination of hydraulic fluid, therefore good filtration needs to be used to

ensure long life and proper operation of the system. Hydraulic system simple or

complex needs protection from contamination; Filters are frequently considered

as a necessary evil and are added to a system as an afterthought instead of a

valuable asset. Proper filter selection and sizing can provide years of reliable

equipment operation and save money that is commonly lost battling

contamination related failures. Approximately 75% of all hydraulic component

failures are attributed to surface degradation caused by contamination and

corrosion. The cost of installing and maintaining suitable filtration is estimated

of the cost associated with contamination related issues, the tip of the

iceberg. Hidden costs of runaway contamination include; unplanned downtime,



component replacement or repair, expenses, fluid replacement, disposal,

maintenance labor hours, troubleshooting time and energy, and waste .

6-2 Recommendations.

 From the conclusion above of this study, it is recommended that the fluid

Contamination source in the Hydraulic system must be checked. Periodic

inspection of the fluid condition and tube or piping connections can save time

consuming breakdown and unnecessary parts replacement and the following

should be checked regularly.

 All hydraulic connections must be kept tight. A loose connection in a

pressure line will permit the fluid to leak out. If the fluid level becomes as

low as to uncover the inlet pipe opening in the reservoir, extensive damage to

the system can result. Loose connections also permit air to be drawn into the

system resulting in a noisy and/or erratic operation.

 Clean fluid is the best insurance for long service life, therefore, check the

reservoir periodically for dirt and other contaminants. If the fluid becomes

contaminated, flush the entire system and add new fluid.

 Filter elements should also be checked periodically. A clogged filter element

will cause higher pressure drops within the system.

 Air bubbles in the reservoir can ruin the valve and other components. If

bubbles are seen, locate the source of the air and seal the leak.

 When hydraulic fluid is added to replenish the system, pour it through a

mesh or fine wire screen (micro mesh or finer). When applicable, pump the

fluid through a 10 micro filter. Do not use a cloth to strain the fluid.

The service life of the product is dependent upon environment, duty cycle,

operating parameters and system cleanliness. Since these parameters vary from

application to application, the ultimate user must determine and establish the

periodic maintenance required to maximize life and detect potential component

failure.

Workers who operate or work near hydraulic machine are at risk of being struck

by the machine or its components (boom, bucket) during operating or travelling.



National institute for occupational safety and health recommended that injuries

and deaths be prevented through training, proper installation and maintenance

work practices and personal protective equipment. (Refs. ]).



References

           

   ., 1996. Failure analysis case study, Metallurgical

laboratory, June 2004 - 24 - Basic Hydraulic Systems.

           nd Edition, John

Wiley, New York, 1980.

, New York, 1967.



Prentice Hall, New Jersey, 1997.

[5] Dailiana H Z, Kotsaki D, Varitimidis S, Moka S, Bakarozi M, Oikonomou

        juries with major

- 

     -pressure injection injury of the hand: an

, trauma: case report with study of the literature. Strategies

in Trauma and Limb Reconstruction, 2008, volume 3(1), pages 27-

     Systems:   

McGraw-Hill, 2001.

         -time

monitoring of hose condition, alerts equipment operators when failure is

imminent.

[9] Parker Hannifin Corporation O-Ring Division 2360 Palumbo Drive

Lexington, KY 40509, www.parkerorings.co.

[10] O-Ring Kits and Accessories Catalog ORD 5742 USA.



Maintenance Engineering Operators Conference Institute Canadian Des Mines,

De La, Metallurgy ET Du Petrol, Sept-files 1 8-2 1 September 1994.



        

nning and Equipment Selection, Hennies, Ayres da

Silva & Chaves (eds), Balkema, Rotterdam, 1996.



- 

        

Maintenance, Magazine 1997. http://www.mtsdine.~om~current/5h-tm97i.d

[15] Industry & Investment NSW  Mine Safety Issues: December 2010, MDG

41 Page 10.

[16 ] Clifford Faszer, James Farquharson, Michel Parent, Matthew Faszer,

           

IAR 1519789 (2007).

] Hydraulic Filtration, 15 www.buydonaldson.com.

] Decreet E-58. Decreet van 8 mei 1986, houdende algemene regelen

omtrent de opsporing en ontginning van delfstoffen (Decreet Mijnbouw).

Staatsblad 28. Paramaribo, Suriname, (1986).

           -





[ ] S. Dabiri, W. A. Sirignanoy, and D. D. Josephz  

Flow Department of Mechanical and Aerospace Engineering, University of

California, Irvine, CA 92697.

[ ] M. Hellemans, The Safety Relief Valve Handbook, Design and Use of

Process Safety Valves to ASME and International Codes and Standards , (1st

edition, Macmillan Company, 2009).

] J. Watton, The Design of a Single-Stage Relief Valve with Directional

Damping , The Journal of Fluid Control Including Fluidics Vol. 18, n. 2, pp.

22



] Basic hydraulic system and components- US Army Avaition logestic

school-Fort Eustis Verginia  -

] Y. Pancar, H.S. Ergur, Hydraulic Circuits, Design and Application ,

(Lecture notes, ESOGU, Eng. Faculty, Mech. Eng. Dept., 2009).

] N. G. Gavrila, S. Sethi,  Best Performance Characteristic of Pressure Relief

Valves and the Amount of Lost Product , Journal of Loss Prevention in the

Process Industries, Vol. 4, n. 4, pp.  -

] Gladky P.M., Alaydi J.Y., Application of hydraulic actuators with pump

controlled system in hydraulic excavators  Vestnic Journal of National

Technology, University of Ukraine, Machine building, Kiev Polytechnic

Institute, Kiev, Ukraine, 2000,  -

[ ] Cutifani, M., Quinn, B. and Gurgenci, H., "Increased Equipment

Reliability, Safety and Availa bility Without Necessarily Increasing The Cost of

Maintenance", Mining Technology Conference, Freemantle WA 10- 1 1

September, 1996, Published by Cooperative Research Center for Mining

Technology.

] Mobile equipment case study / Web :http://www. Hy-pro-filteration -.com .

 

-Mining-Infographic-

lp2.pdf

[ July 2013,

http://www.miningmagazine.com/management-in-action/smooth-

operations?SQ_DESIGN_NAME=print_friendly

[ ] AirROC is a member of the Atlas Copco Surface Drilling Equipment

ROCTM family ,www.atlascopco.com

] Parker Hannifin Ltd. Tachbrook Park Drive Tachbrook Park, Warwick

CV34 6TU .United Kingdom www.parker.com

[] Brendan Casy Web: http://www .HYDRAULIC  SUPERMARKET.com,



[ ] Web: http://www.filter [1] element. Fluid Contamination Under Control

[ ] Web: http: //www. Hydraulics -F M5 - - Manual (reservoir).

[ ] Web: http: //www. E. J. BOWMAN (Birmingham) LTD.

[ ] Web: http://www.Haulroodsafety.com.

[ ] Web: http: //www. Parker Hannifin Corporation (MAERSK Training

Centre).

[ ] Web: http: //www. Parker-O-Ring Kits -and Accessories.

[ ] Web: http: //www. iranfluidpower.com-Caterpillar- SERVICE

TRAINING.

[ ] Web: http://www.Gate_fluid_power_eBook

[ ] Web: http://www.Danfuss fluid power.

[ ] Web: http://www.Donaldson-simple facts about hydraulic filtrati on .

[ ] Web: http: //www. Contamination control in hydraulic system.

[ ] Web: http://www.hydraulic, fittings and equipment technical handbook.

[ ] Web: http://www.Caterpillar- Transmission Maintenance.

[ ] Y. Pancar, H.S. Ergur, Hydraulic Circuits, Design and Application ,

(Lecture notes, ESOGU, Eng. Faculty, Mech. Eng.

[ ] J. S. Cundiff, Fluid Power Circuits and Controls, (First edition, CRC

Press LLC, 2002).

[ ] Web: http://www.hydraulic supermarket.com/books

[ ] Web: http://www.hyco-hydraulic system, training.

[ ] Web: http: //www. China wheel loader steering system.

[ ] Guide to Industrial Hydraulics, Maintenance Manual, (Vickers).

[ ] Web: http://www.Parker Hannifin Corporation Mobile Cylinder Division

Youngstown, OH.

[ ] Web: http://www.Atlas Copco Surface Drill Rigs.

[ ] Web: http://www. Mines Safety Significant Incident Report No. 181.



[ ] Web: http://www.Basic Information for Performing Hydraulic System

Maintenance (safety).

[ ] Health and safety issues.

[ ] Web: http://www.work place solution-national institute for occupational,

safety and health.

[ ] Web: http: //www. LT 15093

[ ] Web: http://www.Maintenance Procedures and Practices for Underground

Mobile Mining Equipment (future work).

[ ] Web: http://www.Caterpillar Asia pacific learning Hydraulic

fundamental.

[ ] Web: http://www. Donaldson hydraulic  contamination level hydraulic .

[ ] Experimental study into the effect of the temperature on the hydraulic

system. University of technology/Bagdad Web: http://www.Pdffactory.

Com.

[ ] Web: http://www.ejowman .co.uk E.J. Bowman (Birmingham) LTD.

[ ] Web: http: //www.Com introduction to hydraulics.

[ ] Web: htt://www.hydraulic supermarket.com/up load fluid power

[ ] Web: http: //www. Hydraulic hose fitting and equipment

[ ] Web: http://www.introduction to mining

[ ] Web: http://www. MQ 37954 P of F

[ ] Web: http://www.Fluid power system dynamics, University of Minnesota

by W. Durfee and Z.Sun.





Appendices

Photographs

Photograph  high expensive machine for large gold industrial



Photograph Old dump truck high down time low productivity-spare parts

very expensive

Photograph  Old dump truck high down time low productivity -spare

parts very expensive.



Photograph  Dump truck type CAT high reliablety and productivty

Photograph  Mining area contamination of solid particles (dust)



Photograph 6 Drilling machine type FLEXIROC



Photograph  Large machine type TEREX high cost high productivity used

on surface mining

Photograph  another type of crawler tractor hauling gold raw material on

dump truck



Photograph  Haul road design and ramp gradients; on mining site.





Photograph  Excavator 5500 HITACHI loading Dump truck



Photograph 1 orifices and fittings



Photograph  Bulldozer cleaning service road to the gold mining site

Photograph 13 - Surface Haulage Accidents...



Photograph Tough design of excavator

Hydraulic Fundamentals1.2 Hydraulic Principles & Components

Major Hydraulic Components

Hydraulic Pump

Reservoir

Directional Control

Valve

Actuators

Photograph 1 - Basic hydraulic components of bulldozer

ResearchGate has not been able to resolve any citations for this publication.

High-pressure injection injuries are rare injuries, characterized by a small puncture wound that is often underestimated by physicians and patients. The injected substance leads to extensive tissue damage and sometimes to loss of the limb. To underline the severity of these injuries and to alert physicians to recognize them and treat them appropriately. Eight patients with injection injuries from lubricants (6) or solvents (2) were treated in a University Orthopaedic Department in a 5-year period. In all patients the mild initial symptoms were aggravated over the next 4-6 hours leading to a severe compartment syndrome of the hand. Five patients were referred with a mean delay of 3.8 days and 3 were treated immediately; all with debridement and compartment release. The total number of procedures per patient was 2 to 5. In 3 patients a heterodigital flap was necessary whereas in one the second ray was amputated. Results were excellent in 5 cases and good in 3. In injection injuries, prompt diagnosis and immediate aggressive surgical intervention are necessary to save the patients' digit/limb. Patients should be informed about the severity of their injury, its potential complications and the multiple surgical procedures that may be required for a satisfactory functional result.

• Nele Verhoeven
• R. Hierner

The real extent of damage in high-pressure injection injuries (grease gun injuries, paint gun injuries, pressure gun in juries) is hidden behind a small and frequently painless punctiform skin lesion on the finger or the hand. These kinds of injuries require prompt surgical intervention with surgical debridement of all ischemic tissue. Possibility of a general intoxication by the fluid must always be ruled out. Postoperative intensive physiotherapy is essential for the final hand function. The initial benign aspect is frequently causing a delay for an adequate treatment while in the mean time the possibility for subcutaneous damage continuously increases. Because of this delay the chance of permanent reduced functionality in the hand or finger amputation raises. Not only the latency time to adequate treatment but also the injected fluid's nature, the pressure, the volume and the location of injection, has influence on the seriousness and extensiveness of subcutaneous damage. All these factors influence the functional outcome of the patient.

• J. Watton

The dynamic characteristics of a single stage pressure relief are investigated using both linearization and exact simulation techniques. A special case of nonlinear damping, which depends upon the sign of the velocity, is studied, and it is shown that this approach gives a satisfactory compromise for dynamic response. A reasonable approximation to the valve frequency response is obtained using a linearized transfer function (assuming a mean value of the viscous damping coefficient), although an exact analogue simulation was needed to improve the comparison with the measured results. Finally it is shown how the dynamics of the relief valve loading system may strongly affect the predictions. A first order approximation to represent the flow into the relief valve was found to be satisfactory for the desired results.

• M. Hellemans

The Safety Valve Handbook is a professional reference for design, process, instrumentation, plant and maintenance engineers who work with fluid flow and transportation systems in the process industries, which covers the chemical, oil and gas, water, paper and pulp, food and bio products and energy sectors. It meets the need of engineers who have responsibilities for specifying, installing, inspecting or maintaining safety valves and flow control systems. It will also be an important reference for process safety and loss prevention engineers, environmental engineers, and plant and process designers who need to understand the operation of safety valves in a wider equipment or plant design context. • No other publication is dedicated to safety valves or to the extensive codes and standards that govern their installation and use. A single source means users save time in searching for specific information about safety valves. • The Safety Valve Handbook contains all of the vital technical and standards information relating to safety valves used in the process industry for positive pressure applications. • Explains technical issues of safety valve operation in detail, including identification of benefits and pitfalls of current valve technologies. • Enables informed and creative decision making in the selection and use of safety valves. • The Handbook is unique in addressing both US and European codes: - covers all devices subject to the ASME VIII and European PED (pressure equipment directive) codes; - covers the safety valve recommendations of the API (American Petroleum Institute); - covers the safety valve recommendations of the European Normalisation Committees; - covers the latest NACE and ATEX codes; - enables readers to interpret and understand codes in practice. • Extensive and detailed illustrations and graphics provide clear guidance and explanation of technical material, in order to help users of a wide range of experience and background (as those in this field tend to have) to understand these devices and their applications. • Covers calculating valves for two-phase flow according to the new Omega 9 method and highlights the safety difference between this and the traditional method. • Covers selection and new testing method for cryogenic applications (LNG) for which there are currently no codes available and which is a booming industry worldwide. • Provides full explanation of the principles of different valve types available on the market, providing a selection guide for safety of the process and economic cost. • Extensive glossary and terminology to aid readers' ability to understand documentation, literature, maintenance and operating manuals. • Accompanying website provides an online valve selection and codes guide.

• Gelu N. Gavrila
• Samir Sethi

A historic introduction to the pressure relief valve evolution leads to the definition of the best performance characteristic of pressure relief valves. The salient features of the valve's best performanace characteristic as a combination of the valve 'best dynamic performance' and the valve 'best discharge capacity' and factors leading to distortions of the best performance characteristic are discussed. The question of the amount of lost product and furgitive emissions is discussed in connection with the accumulated pressure and valve blowdown in light of the Clean Air Act passed by the US Congress.

• Herbert E. MERRITT

A hydraulic system comprises a source of fluid under pressure, supplying working fluid through a supply line, and a flow control valve of the spool type is interposed in the supply line between the source and the work performing means. The flow control valve is itself controlled by pressure in two pilot lines. One pilot line tends to open the valve, and pressure therein is controlled by a variable pressure control valve. The second pilot line is connected to the supply line downstream of the flow control valve so that pressure in the second pilot line is an analog of the working pressure. The analog pressure in the second pilot line shifts the spool to its closed position at a value determined by the pressure in the first pilot line. In the specific embodiment, the effect of the second pilot line closing the valve is to prevent an accumulator, the source of pressure, from being dumped or vented to the tank at a time when a relief valve in the supply line is opened.

Computerized Hydraulic System Design and Analysis Failure analysis case study, Metallurgical laboratory

• E C I T Fitch
• Hong

Fitch E. C. I. T. Hong " Computerized Hydraulic System Design and Analysis " Bar Dyne, Inc., 1996. Failure analysis case study, Metallurgical laboratory, June 2004-24-Basic Hydraulic Systems.

Oil Hydraulic Systems: Principles and Maintenance

• S R Majumdar

Majumdar S.R. "Oil Hydraulic Systems: Principles and Maintenance" McGraw-Hill, 2001.

s Life Sense hose technology designed to provide real-time monitoring of hose condition, alerts equipment operators when failure is imminent

• Eaton

Eaton " s Life Sense hose technology designed to provide real-time monitoring of hose condition, alerts equipment operators when failure is imminent.

Source: https://www.researchgate.net/publication/315795697_Study_of_Failure_in_Hydraulic_Systems

Posted by: blackcurrent06.blogspot.com