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Published on Jan 10, Abstract This paper deals with the details of four wheel steering 4WS system. With the help of this system all the four wheels can be turned to any direction using the steering.
Thus the vehicle can be controlled more effectively especially during cornering and parking. Also the speed of the vehicle can be increased or decreased. The hydraulic 4WS uses a two-way hydraulic cylinder to turn both the wheels in the same direction.
It is not possible to turn them in the opposite direction. This system finds application in off-highway vehicles such as fork lifts, agricultural and construction equipment and mining machinery.
It is also useful in passenger cars, mainly SUVs. Four-wheel steering, 4WS, also called rear-wheel steering or all-wheel steering, provides a means to actively steer the rear wheels during turning maneuvers. It should not be confused with four-wheel drive in which all four wheels of a vehicle are powered.
It improves handling and help the vehicle make tighter turns. Production-built cars tend to understeer or, in few instances, oversteer. The front wheels do most of the steering. Rear wheel turning is generally limited to during an opposite direction turn. During a same direction turn, rear wheel steering is limited to about When both the front and rear wheels steer toward the same direction, they are said to be in-phase and this produces a kind of sideways movement of the car at low speeds.
When the front and rear wheels are steered in opposite direction, this is called anti-phase, counter-phase or opposite-phase and it produces a sharper, tighter turn Why Four-Wheel Steering System?: To understand the advantages of four-wheel steering, it is wise to review the dynamics of typical steering maneuvers with a conventional front -steered vehicle.
The tires are subject to the forces of grip, momentum, and steering input when making a movement other than straight-ahead driving. These forces compete with each other during steering maneuvers.
This causes the vehicle to sway. Each of these must be balanced against the others. The tires are subjected to road grip and slip angle.
Steering input causes the front wheels to turn. The car momentarily resists the turning motion, causing a tire slip angle to form.
Once the vehicle begins to respond to the steering input, cornering forces are generated. The vehicle sways as the rear wheels attempt to keep up with the cornering forces already generated by the front tires. This is referred to as rear-end lag, because there is a time delay between steering input and vehicle reaction.
When the front wheels are turned back to a straight -ahead position, the vehicle must again try to adjust by reversing the same forces developed by the turn. As the steering is turned, the vehicle body sways as the rear wheels again try to keep up with the cornering forces generated by the front wheels.
The idea behind four-wheel steering is that a vehicle requires less driver input for any steering maneuver if all four wheels are steering the vehicle.
As with two-wheel steer vehicles, tire grip holds the four wheels on the road. However, when the driver turns the wheel slightly, all four wheels react to the steering input, causing slip angles to form at all four wheels.
The entire vehicle moves in one direction rather than the rear half attempting to catch up to the front. There is also less sway when the wheels are turned back to a straight-ahead position.
The vehicle responds more quickly to steering input because rear wheel lag is eliminated. Mechanical 4WS In a straight-mechanical type of 4WS, two steering gears are used-one for the front and the other for the rear wheels. This pin engages a second offset pin that fits into a planetary gear.
The planetary gear meshes with the matching teeth of an internal gear that is secured in a fixed position to the gearbox housing. This means that the planetary gear can rotate but the internal gear cannot. A degree turn of the steering wheel rotates the planetary gear to move the slider in the same direction that the front wheels are headed.
Proportionately, the rear wheels turn the steering wheel about 1.This report studies the global Four-wheel Steering System market status and forecast, categorizes the global Four-wheel Steering System market size (value .
The primary objective of the study is to define and segment the global steering market on the basis of. REPORT ON STEERING SYSTEM TROUBLES & CAUSES Submitted to- Submitted by- Mr Rajan Kareer Bharat Chhabria/ Associate professor Bangar Tejas Jagdish/ UCE, RTU, KOTA Ashish Agrawal/ 3rd year Mechanical INTRODUCTION The steering of a four-wheeled vehicle is, as far as possible, arranged so that the front wheels will roll truely without any lateral slip.
Nov 20, · This report studies the global Four-wheel Steering System market status and forecast, categorizes the global Four-wheel Steering System market size (value and volume) by manufacturers, type, application, and region.
This market research report by Marketresearchpro Inc., has vast information about the Commercial Vehicle Steering Systems market and its potential. The report is useful to everyone right from an expert, analyst, manager to an employee as it contains a variety of analytical and statistical data enabling the reader to have a complete overview and an [ ].