The Onspot Automatic Tire chain offers the traction of a
single set of conventional snow chains at the flip of a switch,
without having to stop the vehicle.
An electric switch mounted in the cab provides 12 volts to an
air solenoid mounted on the vehicle's frame rail. Compressed air
to the solenoid is supplied from either the vehicle's onboard air
system or a 12-volt compressed air kit.
When the dashboard switch is activated, the solenoid opens
allowing compressed air to enter the air chamber and lower the
chainwheel so it contacts the inside of the tire. The friction
between the tire and the rubber-covered chainwheel causes the
chainwheel to rotate, creating enough centrifugal force to flail
the chains out in front of the tire. (The principle of the system
is similar to a small generator driven by a bicycle tire to
operate a headlight.)
Six lengths of chain spaced at 60-degree intervals on the
chainwheel ensure that there are always two (2) chains between
the tire and road surface whether you are accelerating, braking
or are in a wheel lockup condition. The traction from the
chainwheel is obtained in forward OR reverse.
When the dashboard switch is turned off, the solenoid exhausts
the air provided to the chain units and return springs in the air
chambers bring the chainwheels back to their resting position.
