JCB Machine

8/16/2019 JCB Machine

1/34

Pushpa Singh 13047E01038

Introduction

A loader (bucket loader, front loader, front-end loader, payloader,

scoop, shovel, skip loader, or wheel loader) is a heavy equipment

machine used in construction to move aside or load materials such as

asphalt, demolition debris, dirt, snow, feed, gravel, logs, raw minerals,

recycled material, rock, sand, woodchips, etc. into or onto another

type of machinery (such as a dump truck, conveyor belt, feed-hopper,

or railroad car).

jesse's hydraulic

Page 1


2/34


HYDRAULIC SYSTEMS IN EARTH MOVING MACHINERY

THE BASIC IDEA OF A HYDRAULIC SYSTEMS

The basic idea behind any hydraulic system is very simple !rce

"ha" is a##lied a" !$e #!i$" is "ra$s%i""ed "! a$!"her #!i$" usi$&

a$ i$c!%#ressile (luid) The fluid is almost always an oil of some

sort. The force is almost always multiplied in the process. The picture

below shows the simplest possible hydraulic system

!n this drawing, two pistons (red) fit into two glass cylinders filled

with oil (light blue) and connected to one another with an oil-filled

pipe. !f you apply a downward force to one piston (the left one in thisdrawing), then the force is transmitted to the second piston through

the oil in the pipe. "ince oil is incompressible, the efficiency is very

good -- almost all of the applied force appears at the second piston.

The great thing about hydraulic systems is that the pipe connecting

the two cylinders can be any length and shape, allowing it to snake

Page 2


3/34


through all sorts of things separating the two pistons. The pipe can

also fork, so that one %as"er cyli$der can drive more than one sla*e

cylinder if desired.

!n a hydraulic system, all you do is change the si#e of one piston and

cylinder relative to the other, as shown here

To determine the %ul"i#lica"i!$ (ac"!r, start by looking at the si#e of

the pistons. Assume that the piston on the left is $ inches in diameter

(%-inch radius), while the piston on the right is & inches in diameter

('-inch radius). The area of the two pistons is +i , r-. The area of the

left piston is therefore '.%, while the area of the piston on the right is

$.$&. The piston on the right is * times larger than the piston on the

left. +hat that means is that any force applied to the left-hand piston

will appear * times greater on the right-hand piston. "o if you apply a

%-pound downward force to the left piston, a *-pound upward

Page 3


4/34


force will appear on the right. The only catch is that you will have to

depress the left piston * inches to raise the right piston % inch.

OPEN AND CLOSED SYSTEMS

An open system is one where the hydraulic fluid is returned into a

large, unpressuri#ed tank at the end of a cycle through the system. !n

contrast, a closed system is where the hydraulic fluid stays in one

closed pressuri#ed loop without returning to a main tank after each

cycle.

N!. a li""le i$"r!duc"i!$ "! "he ear"h %!*i$& %achi$ery

EARTH MOVING MACHINERY

arthmoving equipment is used in the construction industry to shiftlarge amounts of earth, dig foundations and landscape areas. Types of

earthmoving equipment include hydraulic ecavators, bulldo#ers,

compressors and loaders.

ngineering vehicles or construction equipment, including

ecavators. They are heavy-duty vehicles, specially designed for

eecuting engineering and construction tasks. /ther eamples may

include

Articulated Trucks , Augers , 0ackhoes , 0oring 1achines , 2ompact

Articulated 3oa , 2ompact Track 3oader , 2ompact 4tility 3oader ,

2ompactor , 2onstruction Trucks , 2ore 5rill , 2rawler 5ump ,

Page 4

http://www.equipmenttraderonline.com/find/browse/earthmoving/articulated-truckshttp://www.equipmenttraderonline.com/find/browse/earthmoving/augershttp://www.equipmenttraderonline.com/find/browse/earthmoving/backhoeshttp://www.equipmenttraderonline.com/find/browse/earthmoving/boring-machineshttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-articulated-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-articulated-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-track-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-utility-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compactorhttp://www.equipmenttraderonline.com/find/browse/earthmoving/construction-truckshttp://www.equipmenttraderonline.com/find/browse/earthmoving/core-drillhttp://www.equipmenttraderonline.com/find/browse/earthmoving/crawler-dumphttp://www.equipmenttraderonline.com/find/browse/earthmoving/augershttp://www.equipmenttraderonline.com/find/browse/earthmoving/backhoeshttp://www.equipmenttraderonline.com/find/browse/earthmoving/boring-machineshttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-articulated-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-articulated-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-track-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compact-utility-loaderhttp://www.equipmenttraderonline.com/find/browse/earthmoving/compactorhttp://www.equipmenttraderonline.com/find/browse/earthmoving/construction-truckshttp://www.equipmenttraderonline.com/find/browse/earthmoving/core-drillhttp://www.equipmenttraderonline.com/find/browse/earthmoving/crawler-dumphttp://www.equipmenttraderonline.com/find/browse/earthmoving/articulated-trucks


5/34


2rawler Tractor , 2rushers , 5igger 5erricks , 5isc ,5o#ers ,

5redges , 5ump Trucks , cavator Teeth , cavators , 6raders ,

6ravel 0o , 6rinders , 7ydraulic 0reakers , 3oaders,1ini-cavator

, 1otor 6raders , 8ipe 3ayer , 8ressure 5riller , 9ippers , "carifiers ,

"crapers , "creens , "kid-"teers , "kip 3oaders , "urveying

quipment , Testing quipment , Tool 2arriers , Track 5ump , Tractor

3oaders , Trench 9ollers , Trencher Teeth , Trenchers , 4tility :ehicle

, :ibratory 8lows , +ater 8ull , +heel 3oaders .

They are numerous but we will bw discussing only the ma;or

hydraulic systems in some of them. 0ut for a general understanding

here is

/) H!. L!& S#li""ers 0!r1

The simplest hydraulic device that you find in common use today is

the l!& s#li""er. !t contains all of the basic components of a hydraulic

machine

• An engine, normally a small four-stroke gasoline engine,

provides the power for the system. The engine is attached to a

hydraulic oil pump.

• The hydraulic oil pump creates a stream of high-pressure oil,

which runs to a valve.

Page 5

http://www.equipmenttraderonline.com/find/browse/earthmoving/crawler-tractorhttp://www.equipmenttraderonline.com/find/browse/earthmoving/crushershttp://www.equipmenttraderonline.com/find/browse/earthmoving/digger-derrickshttp://www.equipmenttraderonline.com/find/browse/earthmoving/dischttp://www.equipmenttraderonline.com/find/browse/earthmoving/dozershttp://www.equipmenttraderonline.com/find/browse/earthmoving/dredgeshttp://www.equipmenttraderonline.com/find/browse/earthmoving/dump-truckshttp://www.equipmenttraderonline.com/find/browse/earthmoving/excavator-teethhttp://www.equipmenttraderonline.com/find/browse/earthmoving/excavatorshttp://www.equipmenttraderonline.com/find/browse/earthmoving/gradershttp://www.equipmenttraderonline.com/find/browse/earthmoving/gravel-boxhttp://www.equipmenttraderonline.com/find/browse/earthmoving/grindershttp://www.equipmenttraderonline.com/find/browse/earthmoving/hydraulic-breakershttp://www.equipmenttraderonline.com/find/browse/earthmoving/loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/mini+excavatorhttp://www.equipmenttraderonline.com/find/browse/earthmoving/motor-gradershttp://www.equipmenttraderonline.com/find/browse/earthmoving/pipe-layerhttp://www.equipmenttraderonline.com/find/browse/earthmoving/pressure-drillerhttp://www.equipmenttraderonline.com/find/browse/earthmoving/rippershttp://www.equipmenttraderonline.com/find/browse/earthmoving/scarifiershttp://www.equipmenttraderonline.com/find/browse/earthmoving/scrapershttp://www.equipmenttraderonline.com/find/browse/earthmoving/screenshttp://www.equipmenttraderonline.com/find/browse/earthmoving/skid+steershttp://www.equipmenttraderonline.com/find/browse/earthmoving/skip-loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/surveying-equipmenthttp://www.equipmenttraderonline.com/find/browse/earthmoving/surveying-equipmenthttp://www.equipmenttraderonline.com/find/browse/earthmoving/testing-equipmenthttp://www.equipmenttraderonline.com/find/browse/earthmoving/tool-carriershttp://www.equipmenttraderonline.com/find/browse/earthmoving/track-dumphttp://www.equipmenttraderonline.com/find/browse/earthmoving/tractor-loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/tractor-loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/trench-rollershttp://www.equipmenttraderonline.com/find/browse/earthmoving/trencher-teethhttp://www.equipmenttraderonline.com/find/browse/earthmoving/trenchershttp://www.equipmenttraderonline.com/find/browse/earthmoving/utility-vehiclehttp://www.equipmenttraderonline.com/find/browse/earthmoving/vibratory-plowshttp://www.equipmenttraderonline.com/find/browse/earthmoving/water-pullhttp://www.equipmenttraderonline.com/find/browse/earthmoving/wheel-loadershttp://science.howstuffworks.com/transport/engines-equipment/engine.htmhttp://www.equipmenttraderonline.com/find/browse/earthmoving/crawler-tractorhttp://www.equipmenttraderonline.com/find/browse/earthmoving/crushershttp://www.equipmenttraderonline.com/find/browse/earthmoving/digger-derrickshttp://www.equipmenttraderonline.com/find/browse/earthmoving/dischttp://www.equipmenttraderonline.com/find/browse/earthmoving/dozershttp://www.equipmenttraderonline.com/find/browse/earthmoving/dredgeshttp://www.equipmenttraderonline.com/find/browse/earthmoving/dump-truckshttp://www.equipmenttraderonline.com/find/browse/earthmoving/excavator-teethhttp://www.equipmenttraderonline.com/find/browse/earthmoving/excavatorshttp://www.equipmenttraderonline.com/find/browse/earthmoving/gradershttp://www.equipmenttraderonline.com/find/browse/earthmoving/gravel-boxhttp://www.equipmenttraderonline.com/find/browse/earthmoving/grindershttp://www.equipmenttraderonline.com/find/browse/earthmoving/hydraulic-breakershttp://www.equipmenttraderonline.com/find/browse/earthmoving/loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/mini+excavatorhttp://www.equipmenttraderonline.com/find/browse/earthmoving/motor-gradershttp://www.equipmenttraderonline.com/find/browse/earthmoving/pipe-layerhttp://www.equipmenttraderonline.com/find/browse/earthmoving/pressure-drillerhttp://www.equipmenttraderonline.com/find/browse/earthmoving/rippershttp://www.equipmenttraderonline.com/find/browse/earthmoving/scarifiershttp://www.equipmenttraderonline.com/find/browse/earthmoving/scrapershttp://www.equipmenttraderonline.com/find/browse/earthmoving/screenshttp://www.equipmenttraderonline.com/find/browse/earthmoving/skid+steershttp://www.equipmenttraderonline.com/find/browse/earthmoving/skip-loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/surveying-equipmenthttp://www.equipmenttraderonline.com/find/browse/earthmoving/surveying-equipmenthttp://www.equipmenttraderonline.com/find/browse/earthmoving/testing-equipmenthttp://www.equipmenttraderonline.com/find/browse/earthmoving/tool-carriershttp://www.equipmenttraderonline.com/find/browse/earthmoving/track-dumphttp://www.equipmenttraderonline.com/find/browse/earthmoving/tractor-loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/tractor-loadershttp://www.equipmenttraderonline.com/find/browse/earthmoving/trench-rollershttp://www.equipmenttraderonline.com/find/browse/earthmoving/trencher-teethhttp://www.equipmenttraderonline.com/find/browse/earthmoving/trenchershttp://www.equipmenttraderonline.com/find/browse/earthmoving/utility-vehiclehttp://www.equipmenttraderonline.com/find/browse/earthmoving/vibratory-plowshttp://www.equipmenttraderonline.com/find/browse/earthmoving/water-pullhttp://www.equipmenttraderonline.com/find/browse/earthmoving/wheel-loadershttp://science.howstuffworks.com/transport/engines-equipment/engine.htm


6/34


• The valve lets the operator actuate the hydraulic cylinder to split

a log.

• There is also a tank to hold the hydraulic oil that feeds the pump

and usually a filter to keep the oil clean.

The ma;or components of a log splitter are shown below

!n the figure above you can see how the valve can apply both forward

and backward pressure to the piston. The valve used here, by the way,

is referred to as a


7/34


the pump generates the maimum gpm flow rate at a lower pressure.

!t is used, for eample, to draw the piston back out of a log after the

log has been split. 5rawing the piston back into the cylinder takes

very little force and you want it to happen quickly, so you want the

highest possible flow rate at low pressure. +hen pushing the piston

into a log, however, you want the highest possible pressure in order to

generate the maimum splitting force. The flow rate isn=t a big

concern, so the pump switches to its This cylinder is controlled by the

bulldo#er control lever. +hen, the lever is moved to the

right, pressure oil from the hydraulic tank causes the cylinder toetend. 1oving the lever to the left causes the cylinder to

retract.

LIT CYLINDERS5. These are two cylinders which are

controlled by the bulldo#er control lever. +hen the lever is

pushed forward, pressure oil causes the cylinders to etend and

Page 7


8/34


lower the blade. +hen the lever is pulled back, the cylinders

retract and raise the blade.

HYDRAULIC TAN6 >. This is the reservoir for the oil

which controls the movement of the cylinders

7) DUM+ER TRUC6 HYDRAULIC SYSTEM

5ifferent materials and weights require bodies of different shapes and

si#es. The truck or dumper and its body have a hydraulic system

attached to unload the materials or ob;ects inside it. !n some

situations, the trucks and dumper are designed with hydraulic systems

to lift the weights.

Page 8


9/34


There are four main parts to the hydraulic system that fits to the truck

and its body

the hydraulic pump

hydraulic fluid

the arrangement of the piston and cylinder

control valve

. The energy is transported by the hydraulic fluid from one area of the

hydraulic system to the other, and it is then utili#ed to do work, such

as unloading the material from the body or lifting the weight.

+hen the time comes for the material from the truck or dumper body

to be unloaded, the operator flips a switch that gets the hydraulic

system working. This is when the hydraulic motor starts. 7ydraulic

force, or a force or pressure that is very high, is eerted on the fluid

when the hydraulic fluid is sucked by the motor from the reservoir.

Afterward, this high pressure hydraulic fluid is guided by the control

valve to the piston and cylinder arrangement. !n the ma;ority of truck

and dumper bodies, there are typically two pairs of piston and

cylinder arrangements fitted. A single set is ample if there is less of a

load to be lifted. 1oving within the cylinder, in a linear direction, is a

Page 9


10/34


type of long rod called the piston. The height to which the truck or

dumper body can be lifted is determined by the length of the piston

and cylinder, which is sometimes referred to as the stroke length.

The force of the fluid is transferred to the piston when the high-

pressure fluid enters the cylinder, pushing the truck body upward. The

de-energi#ed hydraulic fluid is emitted to the reservoir from the other

side of the cylinder. The continuous lift-up in the piston is maintained

by pumping the high-pressure fluid continuously to the piston and

cylinder system.

The hydraulic fluid moves in a closed cycle within the system in the

truck or dump body. The piston and cylinder, also called the actuator,

receives the energy from the energy in the hydraulic pump and motor.

To ensure completion of lifting heavy loads, there should be no

hydraulic fluid leakage from one side of the cylinder to the other.

Page 10


11/34


+hen this occurs, the energy of the fluid cannot be used and the load

can=t be lifted. !t is crucial between the cylinder and intact piston to

have a good oil seal. !mproper or worn out oil seals are the cause of

most problems with hydraulic system power loss.

The lubrication of the hydraulic system is completed by the hydraulic

fluid that is utili#ed in the hydraulic system. 5ue to various other

leakages and lubrication, there is some amount of loss of hydraulic

fluid. This is remedied by adding hydraulic fluid to your system

regularly.

0ecause the construction and communications fields are growing,

companies are starting to really use these kinds of truck bodies. These

trucks are so comple it can be overwhelming. ?nowing more about

these truck bodies may make you appreciate them more the net time

you see them parked along the road.

Page 11


12/34


8) E9CAVATOR HYDRAULIC SYSTEM

The ecavator=s hydraulic system now uses a variable-displacement,

aial-piston pump with dual outlet and load-sensing and torque-

limiting features. 3oad sensing enables the pump to respond to

changes in load, which prevents bogging down the engine, improves

fuel economy, and etends component life.

"moother operation is provided by a closed-center directional control

valve that manages oil flow for seamless multi-function operation as

speeds and loads change. This feature produces a consistent,

predictable response when a control is actuated.

Page 12


13/34


"maller bore cylinders, combined with higher operating pressure,

improve lifting functions by reducing overall flow requirements. The

smaller cylinders also make more efficient use of engine power.

@inally, a pilot-operated travel control system requires less effort to

operate and makes machine control smoother, with more predictable

response. As with older models, travel can be controlled through a

pair of pedals, or hand levers.

Page 13


14/34


:) MOTOR GRADER HYDRAULIC SYSTEM

The hydraulic motor is driven by hydraulic fluid supplied from a firsthydraulic pump (described hereinafter), whereby the circle is made to

rotate.

The various hydraulic cylinders through are driven by hydraulic

pressure provided from the first hydraulic pump . These cylinders

include, e.g., the pair of lift cylinders, the drawbar shift cylinder , the

blade shift cylinder , the tilt cylinder , and the like as described above.

The pair of lift cylinders are provided separated on the left and right

sides sandwiching the forward frame between them. The lift

cylinders are positioned substantially along the vertical direction and

are attached to the forward frame and the drawbar . The epansion

and contraction of the lift cylinders causes the rear end of the drawbar

to rise and fall, whereby the blade can be made to move in the

vertical direction. The drawbar shift cylinder is positioned slantwise

relative to the vertical direction and is attached to the lateral end of

the forward frame and the drawbar . The epansion and contractionof the drawbar shift cylinder allows the slant angle of the drawbar

relative to the hori#ontal direction to be changed, whereby the slant

angle of the blade can be changed. The blade shift cylinder is

positioned along the longitudinal direction of the blade and is

attached to the circle and the blade . The epansion and contraction

Page 14


15/34


of the blade shift cylinder allows the longitudinal position of the

blade to be changed. The tilt cylinder is attached to the circle and

the blade . The epansion and contraction of the tilt cylinder allows

the blade to swivel up and down about the ais along the hori#ontal

direction, whereby the tilt angle of the blade relative to the direction

of travel can be changed.

HYDRAULIC UNCTIONS

Cr!ss +i$ Cyli$der Elec"r!hydraulic C!$"r!l Tech$i;ue

The hydraulic lock pin oil cylinder is used for pulling out cross pin of

swing frame. The spring in control of reset lowers operator effort and

ensures operator=s precise observation and operation to swing frame>

the hydraulic power is enough to pull out the rusted cross pin even.

T!# Grade C!%#!$e$"s

Page 15


16/34


1ost hydraulic components are famous foreign products of high

quality and reliability.

L!. O#era"!r E((!r"

!mplement controls are designed to reduce operator fatigue. They

feature short lever throws and low effort in both directions. 8roperly

spaced control levers and short lever throws allow the operator to use

multiple controls with one hand.

Hydraulic Sys"e% .i"h 5A 2ontrol :alve (or lectro 8roportional

:alve).

O"her ea"ures

5ual circuit full hydraulic control system for service brake, and wet-

type multi-disc brake for parking brake> "elf-attached accumulator

ensures spare pressure for service brake system and safety driving.

!mported pigeonhole rubber hose can resists the high pressure.

!mported full-flow oil filter.

ea"ures !( Hydraulic +u%#

"washplate, pressure compensation, variable plunger pump, and 5A

valve (or lectro 8roportional :alve) for displacement control.

Page 16


17/34



18/34


fill area where the blade is raised, the back panel of the hopper, or the

e;ector, is hydraulically pushed forward and the load tumbles out.

Then the empty scraper returns to the cut site and repeats the cycle.

/n the elevating sca!e the hopper is filled by a type of conveyor

belt with cutting edges.

"crapers can be very efficient on short hauls where the cut and fill

areas are close together and have sufficient length to fill the hopper.

The heavier scraper types have two engines (=tandem powered=), one

driving the front wheels, one driving the rear wheels, with engines up

to k+ ('& hp). Two scrapers can work together in a push-pull

fashion but this requires a long cut area.

=) TRUC6 CRANES HYDRAULIC SYSTEM

Although everything on the truck begins and ends with the hydraulic

system, there=s more to a hydraulic truck crane than the hydraulics.

There are many components involved in lifting a load. 7ere are the

basic parts of every hydraulic truck crane

Page 18

http://en.wikipedia.org/wiki/Cut_(earthmoving)http://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Cut_and_fillhttp://en.wikipedia.org/wiki/Kilowatthttp://en.wikipedia.org/wiki/Horsepowerhttp://en.wikipedia.org/wiki/Cut_(earthmoving)http://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Conveyor_belthttp://en.wikipedia.org/wiki/Cut_and_fillhttp://en.wikipedia.org/wiki/Kilowatthttp://en.wikipedia.org/wiki/Horsepower


19/34


• 3!!%

• >i

• R!"e, &ear

• Ou"ri&&ers

• C!u$"er.ei&h"s

• Rei$(!rced2s"eel cale

• H!!1

The most recogni#able part of any crane is the !!%. This is the steel

arm of the crane that holds the load. 9ising up from ;ust behind the

operator=s cab, the boom is to heights of several do#en feet. . "ome

Page 19


20/34


21/34


All of this equipment is controlled by the operator inside the cab,

which is located on top of the deck. 2rane operators use several

control mechanisms to raise and lower the boom, rotate the cab and

boom, wind and unwind the winch and control other peripheral

equipment..

8rior to any lift, the operator enters data into a computer inside the

cab, including the weight of the ob;ect to be lifted and the height to

which it is to be lifted. This computer serves as the operator=s backup,

warning the operator if the crane is being pushed beyond its

capability. 4sing a binder of charts in the cab, the operator also

determines the angle of lift and the radius of the boom. /nce all of

this is entered, the computer can track the progress of the lift and

warn the driver if the crane is nearing its limitations

There are at least two other people needed to perform a lift properly,

including the !iler and the si&$al%a$. The oiler is responsible for

making sure that all of the crane=s parts are in place and secured prior

to any lift. 7e or she also acts as a spotter during a lift to ensure that

the lift is being performed properly. The signalman, as the name

suggests, gives hand signals to the operator during the lift to make

sure the load is being maneuvered correctly.

Page 21


22/34


3ac1h!e is a highly effective as well as proficient hefty construction

gear used by ma;or buildings procedure along with roadways. !t is

also called rear professional or perhaps back again professional. That

is easily the most utili#ed development products as a consequence of

its fleibility.

This includes the two main parts, the backhoe plus the loading

machine. The particular ac1h!e loader=s heart can be a tractor base

of which consists of a highly effective powerplant as well as ma;or

trolley wheels. !t=s also a pickup=s cab which safeguards the driver

coming from different climate.

?) 3AC6HOES HYDRAULIC SYSTEM

7ydraulics, levers and the gear pump are combined to make a

backhoe that can be bent and turned in many ways. The three ;oints in

the backhoe can be bent like your shoulder, elbow and wrist. 1any

Page 22

http://back-hoes.org/blog/http://back-hoes.org/blog/


23/34


hoses run from the pimp up the backhoe to supply oil to the hydraulic

rams (pistons). The operator controls the hydraulics in the backhoe

with two ;oysticks.

Two hydraulic pistons connect the boom to the tractor.The pistons

allow the backhoe to rotate from side to side. +hen one of them

pushes, the other pulls, so that the boom can be swung sideways.

There is also a piston connecting the tractor and boom. "ince the

boom is a lever, when the piston pushes or pulls it it rotates on its

fulcrum, which would be its other connection to the tractor. The other

end of the boom, along with the rest of the backhoe attached to it, is

lifted and lowered like this.

The stick and bucket are moved in the same way, with a hydraulic

piston rotating them around the point where they are attached to the

previous part of the backhoe.

The backhoe has two stabili#er legs to keep the tractor steady when

the backhoe is digging. !t also prevents the tractor from falling into

the hole that is being dug.

Page 23


24/34


@) HYDRAULIC LIT SYSTEM

The concept of an elevator is incredibly simple -- it=s ;ust a

compartment attached to a lifting system. Tie a piece of rope to a bo,

and you=ve got a basic elevator.

/f course, modern passenger and freight elevators are a lot more

elaborate than this. They need advanced mechanical systems to handle

the substantial weight of the elevator car and its cargo. Additionally,

they need control mechanisms so passengers can operate the elevator,

and they need safety devices to keep everything running smoothly.

There are two ma;or elevator designs in common use today hydraulic

elevators and roped elevators.

Page 24


25/34


7ydraulic elevator systems lift a car using a hydraulic ram, a fluid-

driven piston mounted inside a cylinder. Bou can see how this system

works in the diagram below.

The cylinder is connected to a fluid-pumping system (typically,

hydraulic systems like this use oil, but other incompressible fluids

would also work). The hydraulic system has three parts

• A tank (the fluid reservoir)

•A pump, powered by an electric motor

• A valve between the cylinder and the reservoir

The pump forces fluid from the tank into a pipe leading to the

cylinder. +hen the valve is opened, the pressuri#ed fluid will take the

path of least resistance and return to the fluid reservoir. 0ut when the

Page 25

http://www.howstuffworks.com/hydraulic.htmhttp://www.howstuffworks.com/motor.htmhttp://www.howstuffworks.com/hydraulic.htmhttp://www.howstuffworks.com/motor.htm


26/34


valve is closed, the pressuri#ed fluid has nowhere to go ecept into

the cylinder. As the fluid collects in the cylinder, it pushes the piston

up, lifting the elevator car.

+hen the car approaches the correct floor, the control system sends a

signal to the electric motor to gradually shut off the pump. +ith the

pump off, there is no more fluid flowing into the cylinder, but the

fluid that is already in the cylinder cannot escape (it can=t flow

backward through the pump, and the valve is still closed). The piston

rests on the fluid, and the car stays where it is.

To lower the car, the elevator control system sends a signal to the

valve. The valve is operated electrically by a basic solenoid switch.

+hen the solenoid opens the valve, the fluid that has collected in the

cylinder can flow out into the fluid reservoir. The weight of the car

and the cargo pushes down on the piston, which drives the fluid into

the reservoir. The car gradually descends. To stop the car at a lower

floor, the control system closes the valve again.

This system is incredibly simple and highly effective, but it does have

some drawbacks. !n the net section, we=ll look at the main

disadvantages of using hydraulics.

+r!s a$d C!$s !( Hydraulics

Page 26


27/34


The main advantage of hydraulic systems is they can easily %ul"i#ly

the relatively weak force of the pump to generate the stronger force

needed to lift the elevator car

0ut these systems suffer from two ma;or disad*a$"a&es. The main

problem is the sie !( "he e;ui#%e$". !n order for the elevator car to

be able to reach higher floors, you have to make the piston longer.

The cylinder has to be a little bit longer than the piston, of course,

since the piston needs to be able to collapse all the way when the car

is at the bottom floor. !n short, more stories means a longer cylinder.

The problem is that the entire cylinder structure must be buried below

the bottom elevator stop. This means you have to dig deeper as you

build higher. This is an epensive pro;ect with buildings over a few

stories tall. To install a hydraulic elevator in a %-story building, for

eample, you would need to dig at least nine stories deepC

The other disadvantage of hydraulic elevators is that they=re fairly

i$e((icie$". !t takes a lot of energy to raise an elevator car several

stories, and in a standard hydraulic elevator, there is no way to store

this energy. The e$er&y !( #!si"i!$ (potential energy) only works to

push the fluid back into the reservoir. To raise the elevator car again,

the hydraulic system has to generate the energy all over again.

The r!#ed ele*a"!r desi&$ gets around both of these problems. !n the

net section, we=ll see how this system works.

Page 27

http://science.howstuffworks.com/transport/engines-equipment/fpte6.htmhttp://science.howstuffworks.com/transport/engines-equipment/fpte6.htm


28/34


The Cale Sys"e%

The most popular elevator design is the r!#ed ele*a"!r. !n ropedelevators, the car is raised and lowered by "rac"i!$ s"eel r!#es rather

than pushed from below.The ropes are attached to the elevator car,

and looped around a shea*e (7). A sheave is ;ust a pulley with a

grooves around the circumference. The sheave grips the hoist ropes,

so when you rotate the sheave, the ropes move too.

The sheave is connected to an electric motor (-). +hen the motor

turns one way, the sheave raises the elevator> when the motor turns

the other way, the sheave lowers the elevator. !n &earless ele*a"!rs,

the motor rotates the sheaves directly. !n &eared elevators, the motor

turns a gear train that rotates the sheave. Typically, the sheave, the

motor and the c!$"r!l sys"e% (/) are all housed in a %achi$e r!!%

above the elevator shaft.

The ropes that lift the car are also connected to a c!u$"er.ei&h" (8),

which hangs on the other side of the sheave. The counterweight

weighs about the same as the car filled to -percent capacity. !n other

words, when the car is percent full (an average amount), the

counterweight and the car are perfectly balanced.

Page 28

http://science.howstuffworks.com/transport/engines-equipment/motor.htmhttp://science.howstuffworks.com/transport/engines-equipment/gear-ratio.htmhttp://science.howstuffworks.com/transport/engines-equipment/motor.htmhttp://science.howstuffworks.com/transport/engines-equipment/gear-ratio.htm


29/34


The purpose of this balance is to conserve energy. +ith equal loads on

each side of the sheave, it only takes a little bit of force to tip the

balance one way or the other. 0asically, the motor only has to

overcome friction -- the weight on the other side does most of the

work. To put it another way, the balance maintains a near constant

#!"e$"ial e$er&y level in the system as a whole. 4sing up the

potential energy in the elevator car (letting it descend to the ground)

builds up the potential energy in the weight (the weight rises to the

top of the shaft). The same thing happens in reverse when the elevator

goes up. The system is ;ust like a see2sa. that has an equally heavy

kid on each end.

0oth the elevator car and the counterweight ride on guide rails (:)

along the sides of the elevator shaft. The rails keep the car and

Page 29


30/34


counterweight from swaying back and forth, and they also work with

the safety system to stop the car in an emergency.

9oped elevators are much more versatile than hydraulic elevators, as

well as more efficient. Typically, they also have more safety systems.

!n the net section, we=ll see how these elements work to keep you

from plummeting to the ground if something goes wrong.

ull #!.er hydraulic ra1e sys"e% (!r ear"h%!*i$& e;ui#%e$"

"ince their introduction in mining, full power hydraulic brake systems

have become common in a large variety of other industries including

earthmoving, material handling, and agriculture. "ome eamples of

machines using full power hydraulic brake systems include wheel

loaders find ecavators, forklifts, telescopic handlers, logging

forwarders, and agricultural harvesters. The full power hydraulic

brake systems for these machines may have slightly different features,

but their underlying concept remains the same.

A full power hydraulic brake system may use the machine=s eisting

hydraulic system as a power source. An accumulator charge valve

directs the machine=s hydraulic system flow into one or more

hydraulic accumulators to maintain the accumulator pressure between

a high and low limit. The hydraulic accumulators store energy for

Page 30


31/34



32/34


function of si#e (diaphragm designs are common when smaller

accumulators may be used) and economics.

3ow-8ressure +arning "witch - The low-pressure warning switch

should be of piston design. This type of design is usually more

durable than the more common diaphragm design. A durable design is

preferable given the switch=s critical function in a full power hydraulic

brake system.

8edal 1odulating :alve - The pedal modulating valve controls the

brake pressure with a positive feedback for the operator. The feedback

is provided by a pilot passage from the brake line to the bottom of the

control spool. 5ifferent diameter control spools can be used to make

feedback more true (i.e. larger diameter spools for lower brake

pressure applications, smaller diameter spools for higher brake

pressure applications).

8edal modulating valves are available in single or tandem (for split

brake systems) design and width vertical or hori#ontal mountings.

Page 32


33/34


8ilot modulated pedal modulating valve designs are available for

remote operation via a solenoid valve or a lever modulating valve.

The advantages of a full power hydraulic brake system over a

common air over hydraulic brake system are many.

D 9edundancy - The system eliminates the need for a redundant

power source (i.e. air systems).

D "i#e - 7ydraulic accumulators are smaller than air storage vessels.

Also, fewer components are required in a hydraulic system.

D 2ontamination - @ull power hydraulic systems are less prone to

contamination than air systems.

D "ervice - @ull power hydraulic systems are less complicated than air systems.

D 2ontrol - 8edal feedback is more true.

D 9esponse - 0rake fill and application is faster.

Page 33


34/34


!n this system, a dual accumulator charge valve and tandem pedal

modulating valve are required for a split brake system. The

accumulator charge valve is an open center design with bypass to

steering, implement andEor tank.

This system also incorporates a park brake valve with auto apply. This

valve will automatically apply the parkEemergency brake if the service

brake accumulator pressure falls below a preset trigger pressure.

A large number of variations of the above circuit are possible. The

final circuit depends on many factors.

The purpose here is to give a brief introduction to the concepts and

advantages of full power hydraulic brake systems. 2lose consultation

with the hydraulic brake system manufacturer is recommended to

insure all applicable brake standards are met at the most economical

cost.

Documents

JCB Machine