PRIEW

Aim

Introduction.

History.

General Circuit .

Component In Power Steering.

Types Of Hmps.

Future Of Power Steering.

Advantages And Disadvantages.

Conclusion.

Bibliography

AIM

Steering is the collection of components, linkages, etc. which allow a vessel (ship, boat) or

vehicle (car, motorcycle, bicycle) to follow the desired course. An exception is the case of rail

transport by which rail tracks combined together with railroad switches (and also known as

'points' in British English) provide the steering function.

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.

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 Reservoir

Must 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

Filters

Oil Filter

Preferably installed in the return line.

A 10-micron or smaller filter is recommended.

Air Breather Filter

The “breather” or vent in the reservoir.

A 3-micron filter is recommended.

COMPONENTS IN POWER STEERING

Pump

Steering gears

Rotary valve

Linkages

COMPONENTS IN POWER STEERING

Power Steering Pump

Usually a vane-type pump or similar.

Driven by the engine.

Power Cylinder

Double-acting differential cylinder.

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

noticeable.

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

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 design

Requires little or no steering linkage modification.

Requires larger space envelope than other types.

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

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 fatigue

Low input torque and continuous steering function

Oil output directly proportional to the steering speed

-In comparison to Non-PW racks, the ratio is quicker. (Less lock-to-lock for the same

turning radius).

Less effort while parking, at low speeds, or on tight turns.

Disadvantages of parisitic loss, oversensitivity and lightness can be lessened by

adding a larger pulley, while possibly retaining the advantages.

Works well for large vehicles.

Generally reguarded as a standard safety device from OEM's.

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.

BIBLIOGRAPHY

How Car Steering Works (HowStuffWorks.com)

2000 technical paper on the kinematic design of rack-and-pinion steering linkages

2002 technical paper on the kinematic design of bellcrank steering linkages

POWER STEERING

Thank you