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POWER STEERING

SUBMITTED BY:

AAKASH MFOURTH YEAR MECHANICAL

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ABSTRACT

Larger tires having weight on vehicles make thecar more difficult in parking. so the driver has to

apply greater physical strength for driving thevehicles. To over come this difficulty, power

assisted steering has been introduced

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INTRODUCTION

When a car is steered manually, the driver has to supply allthe steering effort. The front wheels are turned to the right or

left as per the will of he driver through the mechanicaladvantage of the steering gear and the linkage.

Larger tires having weight on vehicles make the car more

difficult in parking. so the driver has to apply greaterphysical strength for driving the vehicles. To over come this

difficulty, power assisted steering has been introduced

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Automobiles do not have full power steering. They have

only power assisted steering, called power steering. The car

cannot be steered when the engine falls or the power steering

system falls with out mechanical connection between the

steering wheel and the front wheels. The car can be steeredmanually when the power assist is not available.

This power steering system uses compressed air, electrical

devices, and hydraulic pressure. Some are air operated

power steering. But, today also hydraulic oil pressure is used

in all cars and most trucks having power steering systems

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WORKING PRINCIPLE

The power steering consist of a fluid reservoir,hydraulic pump, hydraulic pump, hydraulic ram,control valve, steering shaft and steering wheel.

The engine driven by hydraulic pumps supply oilunder pressure from the oil reservoir to the feed lines.

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A hydraulic control valve providedbelow the steering measures the input

pressure at the steering wheel.Then the pressure is converted in to

the hydraulic ram.

When the steering wheel is stationary

the oil will exert the same pressure onboth sides of the piston and retain the

piston at rest.

When the driver turns the steering

wheel, the control valve is moved bythe steering arm

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At that time, one of the ports closes

while the other one opens.

A high pressure oil enters one sidethere by moving the piston.

Then this movement f the piston

actuates the steering linkage to movein the required direction

This system is used n big cars and

heavy commercial vehicles.

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The main difference between power

steering and annual steering system

is a power booster is attached toassist the driver.

The booster is operated when the

steering shaft turns.When the steering effort exceeds a

certain force, the booster will carry

and gives most of the force requiredfor steering.

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In this case, a hydraulic pressure is

supplied by a pump continually.

When the steering wheel turns,

valves are actuated by this hydraulic

pressure to a cylinder.

Then this pressure makes the pistonto move and provides most of the

steering force.

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REQUIRMENT OF POWER STEERING

WITH SUTABE STEERING FORCE

Although power steering is a

mechanism used for reducing steering

effort, the effort should be varied withthe driving conditions .

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Usually, more steering effort isrequired hen the vehicle stops or moves

at low speed.

At middle range speeds, less steeringeffort is required when the vehicle

speed increases.

Less steering effort is required duringhigh speed driving.

Many models having power steeringwith special devices on the pump andthe gear housing to ensure the proper

steering effort

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ADVANTAGE

Steering effort is decreased by

increasing the gear ratio of thesteering gear.

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APPLICATION

This system is used in big cars and heavycommercial vehicles.

It is vary much suitable for low speed and thevehicle for paring purpose while reversing

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REFERENCE

AUTOMOBILE ENGINEERING-

G.K.VIJAYARAGHAVAN,S.SUNDARAVALLI