Patent attributes
A base unit for a vehicle such as a mobile work platform includes a chassis and multiple wheels, at least one of the wheels being mounted on the chassis by a suspension mechanism including a suspension element. The suspension element pivots relative to the chassis about a substantially horizontal pivot axis between an upper position and a lower position, and a stop member engages the suspension element in the upper position to limit its upwards movement. A biasing mechanism exerts a biasing force on the suspension element to urge the suspension element upwards towards the upper position. The biasing mechanism includes an actuator which adjusts the biasing force so that, in a first operating condition, the biasing force is greater than the force needed to maintain the suspension element in engagement with the stop member when the wheel is suspended, and in a second operating condition the biasing force is less than the force needed to maintain the suspension element in engagement with the stop member when the wheel is suspended.
