The firm explains that a chassis-specific bracket kit is fitted to the rear suspension mounting points under the axle, and air cylinders bolted to it.
Cranked arms attached to the air cylinders carry a hard rubber rimmed chain wheel, which, when deployed moves downward in an arc from its stowed position inside the chassis frame to contact with the inner face of the drive axle tyre.
Several short lengths of chain attached to the underside of the now spinning chain wheel are then directed outwards between the underside of the tyre and the road surface by the centrifugal force of the spinning chains.
Operation of the system is controlled from a rocker switch in the cab. When activated, an electro/pneumatic control valve in the chassis frame near Onspot units, allows air to pass down from the control valve line to the air connections on the cylinders to move the chain wheels into the operating position.
The system is designed to be used at up to 50 kph and the Onspot is also claimed to provide assistance during braking and when reversing.