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.
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Transcript
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