Hydraulic Excavator Parts and Working

CONTENTS
TOPICS PAGE NO.
1. Abstract 1
2. Introduction 2
 Company Overview 3
 Historical Developments 4
3. Types of JCB 5
4. Material Used 13
 Foam Board 14
 Nut & Bolts 14
 Aluminium 14
 Bonding Adhesive 15
 Syringe 15
5. Hydraulic System 16
6. Operating Principle 16
7. Application of Hydraulic Systems 21
8. Pump Lift 23
9. Pressure Regulation 24
10. Designing of Excavator Parts, Joints & Assembly 25
 Static analysis of bucket and lower arm 27
 Kinematic analysis of excavator 28
11. Subsystem Models 35
 Internal combustion engine 35
 Torque Converter 35
 Transmission Axles 36
 Electric Generator and Motors 36
 Battery 36
 Hydraulic Service Kit 37
12. Results 38
13. Conclusion 39
14. References 42

1
ABSTRACT
Excavators or JCBs are used primarily to excavate below the natural surface of the ground on
which the machine rests and load it into trucks or tractor. Due to severe working conditions,
excavator parts are subjected to high loads. The excavator mechanism must work reliably under
unpredictable working conditions. Thus it is very much necessary for the designers to provide
not only an equipment of maximum reliability but also of minimum weight and cost, keeping
design safe under all loading conditions. Hydraulic Excavators are heavy construction
equipment consisting of a boom, arm, bucket and cab on a rotating platform (known as the
"Revolving frame"). The Revolving frame sits atop an undercarriage with tracks or wheels. All
movement and functions of a hydraulic excavator are accomplished through the use of
hydraulic fluid, with hydraulic cylinders and hydraulic motors. Excavators are also called
diggers, mechanical shovels and 360-degree excavators. The purpose of this project is to show
the application of Pascal’s Law in the working of four axis hydraulic JCB using syringe in a
prototype.

2
In the era of globalization and tough competition the use of machines is increasing for the earth
moving works, considerable attention has been focused on designing of the earth moving
equipment. Today hydraulic excavators are widely used in construction, mining, excavation,
and forestry applications. Hydraulic excavators also called diggers. There are many variations
in hydraulic excavators. They may be either crawler or rubber-tire-carrier-mounted, and there
are many different operating attachments. With the options in types, attachments, and sizes of
machines, there are differences in appropriate applications and therefore variations in economic
advantages. Excavator digs, elevates, swings and dumps material by the action of its
mechanism, which consists of boom, arm, bucket and hydraulic cylinders. Bucket is used for
trenching, in the placement of pipe and other under-ground utilities, digging basements or water
retention ponds, maintaining slopes and mass excavation. Due to severe working conditions,
excavator parts are subject to corrosive effects and high loads. The excavator mechanism must
work reliably under unpredictable working conditions.

3
Excavators are heavy construction equipment consisting of a boom, stick, bucket and cab on a
rotating platform known as the "house". The house sits atop an undercarriage with tracks or
wheels. A cable-operated excavator uses winches and steel ropes to accomplish the
movements. They are a natural progression from the steam shovels and often called power
shovels. All movement and functions of a hydraulic excavator are accomplished through the
use of hydraulic fluid, with hydraulic cylinders and hydraulic motors. Due to the linear
actuation of hydraulic cylinders, their mode of operation is fundamentally different from cable-
operated excavators.
Due to severe working conditions, excavator parts are subject to corrosive effects and high
loads. The excavator mechanism must work reliably under unpredictable working conditions.
Poor strength properties of the excavator parts like boom, arm and bucket limit the life
expectancy of the excavator. Therefore, excavator parts must be strong enough to cope with
caustic working conditions of the excavator. The skilled operator also cannot know about the
terrain condition, soil parameters, and the soil-tool interaction forces exerted during excavation
operation are required to find because these forces helpful for better design of the tool, backhoe
parts and for trajectory planning. Normally the exactor is working under cyclic motion during
excavation process. Due to this repetitive nature of work, cyclic stresses are developed in the
parts of backhoe attachment. High level of stresses can cause the damage of critical parts of
excavators and it will adversely affected on productivity of machine. Now a day weight is
major concern while designing the machine components. So for reducing the overall cost as
well as for smoothing the performance of machine, optimization is needed.
COMPANY OVERVIEW:-
J.C. Bamford Excavators Limited, universally known as JCB, is a British multinational
corporation, with headquarters in Rochester, Staffordshire, and manufacturing equipment for
construction, demolition and agriculture. It is the world's third-largest construction equipment
manufacturer. It produces over 300 types of machines, including diggers (backhoes),
excavators, tractors and diesel engines. It has 22 factories across Asia, Europe, North America,
and South America; its products are sold in over 150 countries. JCB was founded in 1945 by
Joseph Cyril Bamford, after whom it is named; it continues to be owned by the Bamford family.
In the UK ' JCB' is often used colloquially as a generic description for mechanical diggers and

4
excavators and now appears in the Oxford English Dictionary, although it is still held as a
trademark.
HISTORICAL DEVELOPMENT:-
The history of JC Bamford Excavators (or JCB as it commonly known) is one of the better
documented stories in the construction equipment industry. Joe Bamford moved his fledgling
company to a small farm in Rochester in 1950 and today, over 40 years later, the company
owns over 2,000 fully landscaped acres on which the plant operates. 1953 saw Mr. Bamford
develop his first backhoe attachment which was fitted with a hydraulic loader to a farm tractor,
and in the same year the JCB logo first appeared. The early machines were not very successful,
but in 1954 JCB launched the first true backhoe loader, whereby the loader and backhoe were
attached to a separate, rigidly constructed chassis, rather than being directly mounted on a
tractor unit. Thus the future mainstay of the company was launched, and throughout the 1950s
and 1960s the company prospered upon the success of its JCB 3, JCB 3C and JCB 4 backhoe
loaders.
In the 56 years since the founding of the company the three letters JCB have become
synonymous with marketing excellence and engineering expertise. The company has
undertaken an extensive programme of product diversification, particularly in the last ten years.
It does not rely on past successes, and in future is likely to continue its diversification
programme as it seeks to carry on the growth pattern of the last twenty years. The rate of growth
is unlikely to be as spectacular, 100 per cent in the last ten years alone, but very importantly
JCB is no longer dependent upon a single product, the backhoe loader, with which its name
will always be associated.
Production of the first engine designed and manufactured by JCB, the JCB444 diesel engine,
started in 2004. Planning of a new £40 million pound JCB Heavy Products site began in 2007
and by the next year, the firm began to move from its old site in Pinfold Street in Uttoxeter to
the new site beside the A50; the Pinfold Street site was demolished in 2009. During that year,
JCB announced plans to make India its largest manufacturing hub. Its factory at Ballabgarh in
Haryana, was to become the world’s largest backhoe loader manufacturing facility. JCB shed
2,000 jobs during the recession, but in 2010 it announced it was recruiting up to 200 new
workers.

11
APPLICATION OF PASCAL’S LAW IN THE WORKING MODEL OF
FOUR AXIS HYDRAULIC JCB USING SYRINGE

14
Foam Board-
Foam core or Foam board is a very strong, lightweight, and easily cut material used for
the mounting of photographic prints, as backing in picture framing, in 3D design and in
painting. It is also in a material category referred to as "Paper-faced Foam Board". It consists
of three layers — an inner layer of polystyrene foam clad with outer facing of either a white
clay coated paper or brown craft paper.
The surface of the regular board, like many other types of paper, is slightly acidic. However
for modern archival picture framing and art mounting purposes it can be produced in a neutral,
acid-free version with a buffered surface paper, in a wide range of sizes and thicknesses.
Nut-Bolts-
A nut is a type of fastener with a threaded hole. Nuts are almost always used opposite a mating
bolt to fasten a stack of parts together. The two partners are kept together by a combination of
their threads' friction, a slight stretch of the bolt, and compression of the parts. In applications
where vibration or rotation may work a nut loose, various locking mechanisms may be
employed: Adhesives, safety pins or lock wire, nylon inserts, or slightly oval-shaped threads.
The most common shape is hexagonal, for similar reasons as the bolt head - 6 sides give a good
granularity of angles for a tool to approach from (good in tight spots), but more (and smaller)
corners would be vulnerable to being rounded off. Other specialized shapes exist for certain
needs, such as wing nuts for finger adjustment and captive nuts for inaccessible areas.
Aluminium-
Aluminium is the most abundant metallic element and constitutes about 8% of the Earth’s crust.
Aluminium salts are widely used in water treatment as coagulants to reduce organic matter,
colour, and turbidity and micro-organism levels. Aluminium intake from foods, particularly
those containing aluminium compounds used as food additives, represents the major route of
aluminium exposure for the general public. The contribution of drinking-water to the total oral
exposure to aluminium is usually less than 5% of the total intake.

15
Bonding Adhesive-
Adhesive bonding is used to fasten two surfaces together, usually producing a smooth bond.
This joining technique involves glues, epoxies, or various plastic agents that bond by
evaporation of a solvent or by curing a bonding agent with heat, pressure, or time. Historically,
glues have produced relatively weak bonds. However, the recent use of plastic-based agents
such as the new “super-glues” that self-cure with heat has allowed adhesion with a strength
approaching that of the bonded materials themselves.
Syringe-
A syringe is a simple pump consisting of a plunger that fits tightly in a tube. The plunger can
be pulled and pushed along inside a cylindrical tube (called a barrel), allowing the syringe to
take in and expel a liquid or gas through an orifice at the open end of the tube. The open end
of the syringe may be fitted with a hypodermic needle, a nozzle, or tubing to help direct the
flow into and out of the barrel. Syringes are often used to administer injections, insert
intravenous drugs into the bloodstream, and apply compounds such as glue or lubricant, and
measure liquids.

16
Hydraulic System-
A hydraulic drive system is a drive or transmission system that uses pressurized hydraulic fluid
to power hydraulic machinery. The term hydrostatic refers to the transfer of energy from flow
and pressure, not from the kinetic energy of the flow.
A hydraulic drive system consists of three parts: The generator (e.g. a hydraulic pump), driven
by an electric motor, a combustion engine or a windmill; valves, filters, piping etc. (to guide
and control the system); and the actuator (e.g. a hydraulic motor or hydraulic cylinder) to drive
the machinery.
Operating Principle-
Pascal's law is the basis of hydraulic drive systems. As the pressure in the system is the same,
the force that the fluid gives to the surroundings is therefore equal to pressure × area. In such
a way, a small piston feels a small force and a large piston feels a large force.
The same principle applies for a hydraulic pump with a small swept volume that asks for a
small torque, combined with a hydraulic motor with a large swept volume that gives a large
torque. In such a way a transmission with a certain ratio can be built.
Most hydraulic drive systems make use of hydraulic cylinders. Here the same principle is used
— a small torque can be transmitted into a large force.
By throttling the fluid between the generator part and the motor part, or by using hydraulic
pumps and/or motors with adjustable swept volume, the ratio of the transmission can be
changed easily. In case throttling is used, the efficiency of the transmission is limited. In case
adjustable pumps and motors are used, the efficiency, however, is very large. In fact, up to
around 1980, a hydraulic drive system had hardly any competition from other adjustable drive
systems.
Nowadays, electric drive systems using electric servo-motors can be controlled in an excellent
way and can easily compete with rotating hydraulic drive systems. Hydraulic cylinders are, in
fact, without competition for linear forces. For these cylinders, hydraulic systems will remain
of interest and if such a system is available, it is easy and logical to use this system for the
rotating drives of the cooling systems, also.

17
The controlled movement of parts or a controlled application of force is a common requirement
in the industries. These operations are performed mainly by using electrical machines or diesel,
petrol and steam engines as a prime mover. These prime movers can provide various
movements to the objects by using some mechanical attachments like screw jack, lever, rack
and pinions etc. However, these are not the only prime movers. The enclosed fluids (liquids
and gases) can also be used as prime movers to provide controlled motion and force to the
objects or substances. The specially designed enclosed fluid systems can provide both linear as
well as rotary motion. The high magnitude controlled force can also be applied by using these
systems. This kind of enclosed fluid based systems using pressurized incompressible liquids
as transmission media are called as hydraulic systems. The hydraulic system works on the
principle of Pascal’s law which says that the pressure in an enclosed fluid is uniform in all the
directions. The force given by fluid is given by the multiplication of pressure and area of cross
section. As the pressure is same in all the direction, the smaller piston feels a smaller force and
a large piston feels a large force. Therefore, a large force can be generated with smaller force
input by using hydraulic systems.

19
The hydraulic systems consists a number of parts for its proper functioning. These
include storage tank, filter, hydraulic pump, pressure regulator, control valve, hydraulic
cylinder, piston and leak proof fluid flow pipelines. It consists of:
• A movable piston connected to the output shaft in an enclosed cylinder
• Storage tank
• filter
• Electric pump
• Pressure regulator
• Control valve
• Leak proof closed loop piping.
The output shaft transfers the motion or force however all other parts help to control the system.
The storage/fluid tank is a reservoir for the liquid used as a transmission media. The liquid used
is generally high density incompressible oil. It is filtered to remove dust or any other unwanted
particles and then pumped by the hydraulic pump. The capacity of pump depends on the
hydraulic system design. These pumps generally deliver constant volume in each revolution of
the pump shaft. Therefore, the fluid pressure can increase indefinitely at the dead end of the
piston until the system fails. The pressure regulator is used to avoid such circumstances which
redirect the excess fluid back to the storage tank. The movement of piston is controlled by
changing liquid flow from port A and port B. The cylinder movement is controlled by using
control valve which directs the fluid flow. The fluid pressure line is connected to the port B to
raise the piston and it is connected to port A to lower down the piston. The valve can also stop
the fluid flow in any of the port. The leak proof piping is also important due to safety,
environmental hazards and economical aspects. Some accessories such as flow control system,
travel limit control, electric motor starter and overload protection may also be used in the
hydraulic systems which are not shown in figure.

21
Applications of Hydraulic Systems:-
The hydraulic systems are mainly used for precise control of larger forces. The main
applications of hydraulic system can be classified in five categories:
• Industrial: Plastic processing machineries, steel making and primary metal extraction
applications, automated production lines, machine tool industries, paper industries,
loaders, crushes, textile machineries, R & D equipment and robotic systems etc.
• Mobile hydraulics: Tractors, irrigation system, earthmoving equipment, material
handling equipment, commercial vehicles, tunnel boring equipment, rail equipment,
building and construction machineries and drilling rigs etc.
• Automobiles: It is used in the systems like breaks, shock absorbers, steering system,
wind shield, lift and cleaning etc.
• Marine applications: It mostly covers ocean going vessels, fishing boats and navel
equipment.
• Aerospace equipment: There are equipment and systems used for rudder control,
landing gear, breaks, flight control and transmission etc. which are used in airplanes,
rockets and spaceships.
The reciprocating pump is a positive plunger pump. It is also known as positive
displacement pump or piston pump. It is often used where relatively small quantity is
to be handled and the delivery pressure is quite large. The construction of these pumps
is similar to the four stroke engine as shown in figure. The crank is driven by some
external rotating motor. The piston of pump reciprocates due to crank rotation. The
piston moves down in one half of crank rotation, the inlet valve opens and fluid enters
into the cylinder. In second half crank rotation the piston moves up, the outlet valve
opens and the fluid moves out from the outlet. At a time, only one valve is opened and
another is closed so there is no fluid leakage. Depending on the area of cylinder the

22
pump delivers constant volume of fluid in each cycle independent to the pressure at the
output port.

23
Pump Lift-
In general, the pump is placed over the fluid storage tank as shown in figure 5.1.5. The pump
creates a negative pressure at the inlet which causes fluid to be pushed up in the inlet pipe by
atmospheric pressure. It results in the fluid lift in the pump suction. The maximum pump lift
can be determined by atmospheric pressure and is given by pressure head as given below:
Pressure Head, P = ρ g h
Theoretically, a pump lift of 8 m is possible but it is always lesser due to undesirable effects
such as cavitation. The cavitation is the formation of vapor cavities in a liquid. The cavities can
be small liquid-free zones ("bubbles" or "voids") formed due to partial vaporization of fluid
(liquid). These are usually generated when a liquid is subjected to rapid changes of pressure
and the pressure is relatively low. At higher pressure, the voids implode and can generate an
intense shockwave. Therefore, the cavitation should always be avoided. The cavitation can be
reduced by maintaining lower flow velocity at the inlet and therefore the inlet pipes have larger
diameter than the outlet pipes in a pump. The pump lift should be as small as possible to
decrease the cavitation and to increase the efficiency of the pump.

24
Pressure Regulation-
The pressure regulation is the process of reduction of high source pressure to a lower working
pressure suitable for the application. It is an attempt to maintain the outlet pressure within
acceptable limits. The pressure regulation is performed by using pressure regulator. The
primary function of a pressure regulator is to match the fluid flow with demand. At the same
time, the regulator must maintain the outlet pressure within certain acceptable limits.
The schematic of pressure regulator and various valves placement is shown in figure. When
the valve V1 is closed and V2 is opened then the load moves down and fluid returns to the tank
but the pump is dead ended and it leads to a continuous increase in pressure at pump delivery.
Finally, it may lead to permanent failure of the pump. Therefore some method is needed to
keep the delivery pressure P1 within the safe level. It can be achieved by placing pressure
regulating valve V3. This valve is closed in normal conditions and when the pressure exceeds
a certain limit, it opens and fluid from pump outlet returns to the tank via pressure regulating
valve V3. As the pressure falls in a limiting range, the valve V3 closes again.

25
Designing of Excavator Parts, Joints and Assembly
The figure shows the 3D solid model of the backhoe attachment. The names of the different
parts of the attachment are labeled in the figure. As can be seen from the figure, there are mainly
five links starting from the base link or fixed link, assembled with the swing link by pin joints,
that in turn assembled with the boom by pin joint, that again in turn assembled with the arm by
a pin joint, and the arm is assembled to the bucket by pin joints, intermediate link, and by idler
links.
The joint actuators to operate the mechanism are the hydraulic cylinders with piston rods inside
it. The boom cylinder rotates the boom from the joint between the boom and the swing link.
Similarly, the arm and the bucket cylinders rotate the arm and the bucket from their fulcrums
respectively. The swing cylinders impart the swing motion of the backhoe attachment from the
boom to swing link joint in order to load or unload the material (transferring the excavated
material or coming back to the digging position) into the dump trucks or trolleys.
The figure given below shows the 3D model of the bucket assembly of the backhoe excavator.
The description of the ballooned parts is given in table. As can be seen from the figure, the
bottom plate is covered at both the sides by side protectors to fill the material inside the bucket.
Two side shear plates are placed over these side protectors in assisting the digging task as well
as preventing the bucket bottom plate, mounting lugs, and side protectors from the wear. The
stiffeners at the bottom plate are provided so as to make the bottom plate more strengthen. The

26
bucket teeth are mounted on the leap plate that in turn is attached to the bottom plate, and leap
plate is thicker than the bottom plate so as to support the bucket teeth firmly.

27
In order to determine the forces and the kinematic analysis of the assembly of the excavator,
the basic mechanism and component of excavator are understood and then static force analysis
for digging operation according to SAE J1179 was carried out. Ductile material that is
HARDOX400 was selected for bucket and bucket rod. Then CAD model was imported and
then discretization of model were carried out for refinement of solution in hyper mesh.
A. Static analysis of bucket and lower arm
In this part, the CAD model of bucket and lower arm are discretized in Hyper mesh software.
The meshed model of bucket essentially consists of 38195 nodal points and 21927 elements.
Out of these elements 20459 are HEXA elements and 1468 are PENTA elements with total
112140 degree of freedoms.

28
B. Kinematic analysis of excavator
Instead of individual parts entire assembly of excavator is taken to carry out kinematic analysis.
It involves various steps as follow:
• Initially individual parts were meshed in hyper mesh same way as for static analysis
• Then each part was imported in hyper mesh one by one and various kinematic joints
are defined in between them.
• Values of motion acceleration and time for simulation was given in analysis
• Then entire assembly was submitted to Altair Motion solve for solving kinematic
problem of the model.
Figure shows final assembly of excavator with kinematic joints. Various joints added in
between various parts are as below:
• Rotational Joints: Upper arm- Upper control cylinder, Upper Arm- Lower arm, Lower
arm-Bucket, Bucket- Control Bucket Coupler, Lower arm- arm control coupler, Bucket
control coupler –Lower control Piston etc.
• Translational joints: Lower control Piston- Cylinder, upper control Piston- Cylinder

29
A backhoe excavator is a robotic construction machine used primarily to excavate the earth
surface. In the selection of a backhoe excavator the terms of the excavating and dumping
capacities become extremely important to know such as: maximum digging depth, maximum
digging height, maximum dumping height, maximum digging reach etc. These positions define
the working range or the work space of the backhoe excavator in context of its operations like
digging and dumping.
These working ranges can either be found out from the simulation of the backhoe excavator
assembly in the CAD tool (modeling software) or can be found out by the programming the
mathematical kinematic model using MATLAB or any other programming language.

30
In Figure a schematic drawing of a typical excavator under consideration is shown. It consists
of a chain track and the hydraulic propel drive which is used to maneuver the machine but
usually not during a work cycle. On top of that is a carriage where the operator is sitting. It can
rotate around a vertical axis with respect to the chain track. It also holds the Diesel engine, the
hydraulic pumps and control system. Furthermore, there is a boom, an arm and at the end a
bucket which is attached via a planar kinematic loop to the arm. Boom, arm and bucket can be
rotated by the appropriate cylinders.
The figure given below shows that the required pressures in the cylinders depend on the
position. For the “stretched” situation the pressure in the boom cylinder is 60 % higher than in
the retracted position. Not only the position but also the movements have to be taken into
account. The next figure shows a situation where the arm hangs down. If the carriage does not
rotate there is a pulling force required in the cylinder. When rotating – excavators can typically
rotate with up to 12 revolutions per minute – the force in the arm cylinder changes its sign and
now a pushing force is needed. This change is very significant because now the “active”
chamber of the cylinder switches and that must be taken into account by the control system.
Both figures demonstrate that a simulation model must take into account the couplings between
the four degrees of freedom this excavator has.

31
The strength analysis is an important step in the design of excavator parts. Finite Element
Analysis (FEA) is the most powerful technique in strength calculations of the structures
working under known load and boundary conditions. One can determine the critical loading
conditions of the excavator by performing static force analysis of the mechanism involved for
different piston displacements. The boundary conditions for strength analysis will be
determined according to the results of static force analysis. In general, computer aided drawing
(CAD) model of the parts to be analyzed must be prepared prior to the FEA. Preparation of the
CAD model can be done either using a commercial FEA program or using a separate
commercial program, which is specialized for CAD. Structural optimization for strength is a
popular subject in modern engineering design. It has been widely used to obtain an optimum
strength/material mass ratio for structures under specified load conditions. The FEA and
optimization is versatile tool for designing the backhoe attachment in hydraulic excavator. The
next section includes the research work carried out by other researchers in the same field. It
can be helpful to the new researchers for reducing the failure problems of backhoe components
and getting optimized design without compromise with its strength and performance during
digging operation.

32
Stresses in Boom in worst position

33
Different axis of working and Range of JCB Excavators

35
Subsystem models
Internal combustion engine
The engine model is arranged in such a way that it provides a torque, depending on the engine
speed and the throttle position signal, to the driveline. The output torque is computed as a
function of the two inputs defined in a 2D lookup table. The detailed thermodynamic and mass-
transport models were not required for the assumed efficiency level.
The engine map includes the ‘engine off’ region in the form of negative torque that is
proportional to speed.
Torque converter
The torque converter model used in the simulations is a steady-state torque converter with no
dynamics taken into account, as this was found to be sufficiently accurate for the purpose of
this study.
The torque converter characteristics are determined by the two curves which are the torque
ratio TR and the capacity factor K as functions of the speed ratio SR. Figure shows the
characteristics (including efficiency) of a particular torque converter.

36
Transmission and axles
A detailed model for the Power shift transmission and axles has been built by means of basic
gear, shaft, inertia and clutch blocks available in the standard powertrain and mechanical
libraries provided within AMESim. These models were then validated using actual test data in
such a way that the power losses which occur in the real transmission and axles are included in
the simulation models.
Electric generator and motors
The models of the electric generator and motors have been built in the MATLAB/ SIMULINK2
environment based on the mathematical model presented by Atallah et al. (1999), Mestha and
Evans (1989) and Casanellas (1994). It was possible to use SIMULINK models thanks to the
cosimulation interface offered by AMESim. These models determine the losses within a
brushless ac permanent magnet machine.
Battery
A battery model is provided within AMESim and it is an internal resistance type, which
characterizes the battery by a voltage source and an internal resistance, Figure 7. The simplicity
of this model is sufficient for the purposes of our simulations. Further information on this and
more advanced battery models can be found elsewhere, e.g., Bejan and Dan (1997) and Johnson
(2002).
The battery output voltage V is calculated as follows:

37
Hydraulic service circuit
The hydraulic service circuit built within this model is very simplified and its main purpose is
to reproduce the power demand imposed on the engine while lorry loading or shoveling. The
modelled circuit involves the following components: hydraulic pump, pipes and actuator. The
mass of boom, arm and handled material is represented by one mass block. In cases of the
series and split hybrids a 30 kW electric motor was modelled to propel the hydraulic pump. In
case of the parallel hybrid configuration the hydraulic pumps were connected directly to the
engine, as in a standard backhoe loader.

38
Result
Hence we see in this project about the different types of JCB or Excavators and their
characteristics. We see the various parts of JCB and their assemblies. We also see the forces
and stresses developed in the JCB and their designing considerations along with the Kinematic
analysis of different parts.
The main objective of this project was to show the working of JCB in various loading and
unloading conditions using a working model of four axis pneumatic JCB using syringe. We see
that from Pascal’s Law (which states that the intensity of pressure at a point in a static fluid is
constant in all directions) that the force and energy is transferred from one point to another
point by use of hydraulic fluid and the force applied can be varied by varying the area and thus
affecting the efficiency of the mechanism. Thus the pressure energy in the JCB is converted to
Mechanical energy to produce the desired motion.

39
Conclusion
The working of Hydraulic JCB can be understood by using the working model of Four Axis
Hydraulic JCB using syringe which incorporates Pascal’s Law as the prime mover as by
converting the pressure energy of the hydraulic fluid to mechanical energy and thus producing
the desired movement in the four axis. By using a proportional ‘soft stop’ system on the higher
lift machines, Adaptive Load Control overcomes the problem caused by a sudden stop creating
additional inertia from a combination of weight and high reach, that can increase the risk of
machine forward overturn. The proportional flow reduction used for the high reach machines
also maximizes speed of operation so that the operator’s ability to use the machine’s full
operating envelope is not compromised.
Advantages:-
• It uses ‘incompressible’ fluid which results in a greater, more efficient and consistent
work or power output.
• As opposed to the pneumatic system which uses air, a leakage in the hydraulic system
is easy to spot during ground maintenance operations.
• Hydraulic fluid operates very well in a very hot working environment as compared to
pneumatic system.
Disadvantages:-
• Hydraulic fluid can be corrosive.
• Due to heavy loads experienced in a typical hydraulic system structural integrity is a
must which also means higher structural weight for the aircraft in addition to the weight
of its hydraulic lines, pumps, reservoirs, filters.
Applications of Pascal’s Law:-
• Hydraulic Lift
• Hydraulic Brake
• Hydraulic Pumps

Hydraulic Excavator Parts and Working

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