Friday, November 04, 2005


Our School Bus fleet uses automatic tire chains made by a company called ONSPOT. They are used on buses that run in severe winter conditions and get two thumbs up from our drivers.

Turning on the auto chain switch energizes a solenoid that directs air pressure instantly to the actuating air chambers.

The photo above shows the electric solenoid. A 12 volt supply comes from the dash switch energizing the solenoid. This allows reservoir air pressure out through the application air lines, actuating the ONSPOT chainwheel arms.

The auto tire chains are now in the applied position as shown above. There are some special installation instructions that must be followed to ensure proper operation.
  • chainwheels are color coded: RED for the driver side and BLUE for the passenger side
  • the chainwheel should contact the tire at the vertical centerline of the tire
  • the pitch of the chainwheel should be O to -1 degree
  • operating angle should be 8 to 15 degrees
  • vertical distance from the ground to the chainwheel contact point should be 3 1/2 to 4 in.

Auto chains work very well and parts are easily accessible. Having a School Bus fleet means making sure the pupils get to school and back home again. Auto chains make our job easier with less worry and service calls. For winter driving these chains are invaluable!

For more information checkout


  • Motor Oil & Filtration

  • Trust My Mechanic
  • No comments :