Seminar on

Power Steering

System In

AutomobilesPresented by

Parth Pramod Kasarekar

(08EAUME031)

Mechanical engineering branch

Aravali Institute of Technical studies,

Udaipur.(Raj.)

Introduction.Functions of steering system.Power steeringHistory.General Circuit .Component In Power Steering.Types of HMPS.Future of Power Steering.Advantages and Disadvantages.Conclusion.

Power Steering

Introduction

Steering is the term applied to the collection of components, linkages, etc. which allow for a car or other vehicle to follow a course determined by its driver.

Functions of steering systems

Control of front wheel (sometimes rear wheel) direction.

Transmit road feel to the driver’s hand.

Maintain correct amount of effort needed to turn the wheel.

Absorb most of the shock going to the steering wheel as the tire hits holes and bumps in the road.

Allow the suspension action.

Power steering

Power steering normally use an engine driven pump and a hydraulic system to assist steering action.

Three major types of power steering systems are:

Internal-piston linkage system

External power steering system

Rack-and-pinion system1)Integral power piston.

2)External power piston

Integral rack-and-pinion system is the most common.

History of Hydro-mechanical Power Steering (HMPS)

Hydro-mechanical power steering was the first type to be used on agricultural tractors in the early 1950’s. Suitable for small to medium tractors where power steering can be an option to manual steering. Once the size of the tractor becomes too big for manual steering, hydro-mechanical steering is usually not cost effective.

General Circuit

Oil ReservoirMust be large enough to hold more than all of the oil for the system.

Should be capable of dissipating heat in oil.

Hydraulic Lines

Flexible hoses due to the steering components movements.

General Circuit

FiltersOil Filter

Preferably installed in the return line.

A 10-micron or smaller filter is recommended.

Air Breather FilterThe “breather” or vent in the reservoir.

A 3-micron filter is recommended.

Components in Power Steering

Pump Steering gears Rotary valve

Linkages

Component discriptions

Power Steering PumpUsually a vane-type pump or similar.

Driven by the engine.

Power CylinderDouble-acting differential cylinder.

Steering response to left and right turns is slightly different. Hardly noticeable.

Vane Type of Pump

ROTARY VALVE

Split Gears

It converts the rotational motion of the steering wheel into the linear motion needed to turn the wheels.

It provides a gear reduction, making it easier to turn the wheels.

Steering Gear Box

Steering gears are enclosed in a casing known as steering gear box ( as shown in Fig.)

Recirculating-ball Steering

The first part is a block of metal with a threaded hole in it. Works similar to a bolt that sticks into the hole in the block.

These are used in havy duty comurcial vehicles.

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Power Rack-and-pinion

There are mainly four types of Hydro mechanical power steering(HMPS). they are as follows:

1)HMPS Type 1

2)HMPS Type 2

3)HMPS Type 3

4)HMPS Type 4

HMPS Type 1The integral valve and actuator coupled to steering linkage.

Easiest to adapt to an existing mechanical steering layout. Only two hoses are neede

• First system layout makes use of an integral valve and actuator coupled directly to the pitman arm and connected to the steering wheel mechanically. this system type is the easiest to use when converting an existing mechanical steering linkage to hydraulic power assist. It is very simple in that it only requires a supply and return line.

• But unfortunately it may not be very asthetic and hoses can be easily exposed to the surrounding moving parts.

HMPS Type 2Steering column mounted control valve with separate, remote actuator

coupled to a linkage member.

Creates a highly congested area with all of the hoses.Four Hoses are needed: supply, return and a pair to the actuator.Creates noise, heat and vibration

HMPS Type 3Control Valve and actuator separately mounted in the steering linkage.

Keeps the area around the steering wheel from becoming too congested. Four hoses are required.

HMPS Type 4The control valve and the actuator are mounted on the steering column, the actuator drives the pitman arm by rack and pinion or by crank arm

means.

Most sophisticated designRequires little or no steering linkage modification.Requires larger space envelope than other types.

The Future of Steering - Drive by Wire

As the majority of today’s hydraulic power steering systems are designed to have the steering pump running constantly, pumping fluid around the system, it wastes valuable horsepower, which translates into wasted efficiency and therefore fuel.

One concept is the "steer-by-wire" or "drive-by-wire" system. These system would completely eliminate the mechanical connection between the steering wheel and the steering, replacing it with a purely electronic control system.

Advantages

Preventing the wheels from transferring the load to the steering column Reducing the driver’s fatigueLow input torque and continuous steering function Oil output directly proportional to the steering speed

Disadvantages

Design is compications and increased in cost.Fluid leakage.

Conclusion

By studing all these we can conclude that the power stering is nesessory for the modern cars.

Now a days we can see almost all cars having a power steering.

It provides good handling to the driver, gives better comfert, and make him less fatigue.

Power Steering

Thank you