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TERM PAPER ON:

HYDRAULIC SYSTEM

PRESENTED BY:GOPAL CARPENTER12-543-008

The term hydraulics is Hydor+aulosHydor means waterAulos- pipe

Necessity of hydraulics:1.To lift or load the implement

2.To set the draft at the time of tillage operations

Pascals Law Pressure exerted at any point on

a confined liquid is transmitted

undiminished in all directions.

Pressure applied to piston A is transferred equally to a piston of the same size B because PSI is the same throughout the system.Basic principle

Pascals Law

Pressure applied to a confined fluid is:transmitted undiminished in all directions, acts with equal force on equal areas, and acts at a right angle to the walls of the container.

10 psi

10-lb1 in2Area = 10 in2Force = 100-lbs.

Important Properties:ShapelessnessLiquids have no neutral formConform to shape of containerEasily transferred through piping from one location to another IncompressibilityLiquids are essentially incompressibleOnce force is removed, liquid returns to original volume (no permanent distortion)Transmission of ForceForce is transmitted equally & undiminished in every direction -> vessel filled with pressure

Components of hydraulics:1.Reservoir

2.Hydraulic pump

3.Hydraulic cylinder

4.Hydraulic piston

5.Control valve

6.Relief valve

7.Lifting arms

8.load

Hydraulic circuit:

A hydraulic circuit is a system comprising an interconnected set of discrete components that transport liquid.

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PumpFunctions in a hydraulic system by pressurizing and moving fluid from one part of the system to another.

Hydraulic pumps are usually of three types:

1. GEAR PUMP2. PISTON PUMP 3. VANE PUMP

Gear Pumps:Fixed or constant displacement pump.Work well at 1500 psi and belowWork with a minimum of moving partsLess expensive to manufacture than piston type pumps

Gear Pumpdriven gearidler gear

Piston PumpsWork well at 2000 psi or more.Require several pistons working together to generate enough volume for tractor applicationsNecessarily involve many moving partsTwo types-1.Axial piston pump2.Radial piston pump

Vane pumpAlso works at 1500 psi and belowThree types-1.sliding vane2.swinging vane 3.Rolling vane

Hydraulic Cylinders:The main function of a cylinder is to convert hydraulic power into linear mechanical force.This force performs work or transmits power.Types : 1.Ram cylinder 2.Single Acting 3.Telescopic 4.Spring Return 5.Double Acting

Ram Cylinders:The simplest single acting cylinderOne fluid chamberExerts force in only one directionMounted mostly verticallyThe cylinder retracts by the force of the load due to gravityRam cylinders are most commonly used in elevators, jacks, and automobile hoists.

Single Acting Cylinders:Acts much like a ram cylinderMain difference is that the single acting cylinder uses a piston. The leakage flow that goes past the piston is ported the tank. Telescopic Cylinders: Mostly a single acting cylinder Series of rod segments called sleeves, most common to only have 4 or 5 sleeves in each cylinder The sleeves work together to provide a longer stroke The maximum force is at the collapsed position The speed will increase at each stage, but will not allow as much force.

Spring Return Cylinders:Considered a single acting cylinderPressure applied to the cap end pushes the spring down as the rod is extendingWhen the pressure is removed the spring force allows the cylinder to retractThe drain is in the spring chamber and allows the leakage flow past the piston seal

Double Acting Cylinders:Types:-1.Double acting (differential cylinder)2.Double rod cylinder (nondifferential cylinder) 3.TendomPressure is applied to both rod end and cap endRod extension is slower because has a larger area, but allows a greater force because of the bigger area.Retract is faster because of the smaller area, but the force allowed is smaller because of the smaller area.

Double Acting Cylinders:Tandem Cylinder-Two pistons in line with a common rodThis allows you to have a greater forces without increasing the size of the cylinder boreTandem cylinders are used in places where there is insufficient space to increase the size of the cylinder bore.

Control valves:Functions of a valve:-1.direct the flow of fluid2.regulate the pressure3.control volumeThree types of valves:Pressure adjust psi for some purposeDirectional -- route the fluid to the desired actuator Volume Control or Flow Control -- control the amount of flow

Accumulators:Types:-PistonMost commonBladder Gun mountsSteering systemsDirect contactLeast common

Hydraulic oil:Purposes:- 1.Compressibility 2.Lubrication 3.Sealing 4.Cooling

12/4/201225Fluid Properties:These properties include:Viscosity and Viscosity IndexPour PointSpecific gravityThermal properties- specific heat & thermal conductivityLubricating AbilityRust and corrosion protectionFire resistance

Filters:Hydraulic lines:

Hydraulic system types:Open center system.Closed center system.

OPERATION OF HYDRAULICSYSTEM

Basic Hydraulic System OperationPumpDirectional Control ValveCylinder

Reservoir

Pressure Relief Valve

Hydraulic

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