FOUR WHEEL STEERING SYSTEMS

FOUR WHEEL STEERING SYSTEMS

INTRODUCTION:

Here is a new concept of ‘Four Wheel Steering (4ws)’. It is different from our normal two wheel steering (2ws) in the way that all the four wheels are steered unlike the 2ws in which only the front wheels are steered.

WHY 4WS ?

Four wheel steering greatly improves the manoeuvrability of the machine and improves the turning circle by about 40% . In addition the rear wheels will also follow the front ones so there is only one wheel track when turning.

How It Works?

Each axle is fitted with a fully enclosed, waterproof, position sensor on top of one of the steering kingpins. When the front wheels are turned the voltage from the front sensor will increase or decrease depending on the direction of the turn and the steering angle. An electronic “brain” continuously monitors the voltage signal from each sensor. If the voltage differs between the two sensors then the computer sends a signal to an electronic, proportional spool valve which, in turn, diverts oil to the steering ram on the rear axle until the two voltage signals are matched and the rear wheels lined up with the front. This all happens instantaneously as the signals are monitored and corrections made hundreds of times every second so as you turn you get the impression that the steering on the two axles is physically connected. For the electronic control in the two wheel steering mode the front sensor is ignored and a signal is taken from a fixed voltage source. Should the rear wheels then try to creep through any oil leakage then a voltage difference will be seen and the rear wheels will be corrected to the straight-ahead position


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