A vehicle’s spring brakes must be capable of holding the vehicle in place. If the test is being conducted on a towing vehicle and trailer, select the vehicle on which to perform this test. It is preferable that this test be performed on the spring brakes of the towing vehicle. However, when a towing vehicle is pulling a trailer, it may not be possible to test its spring brakes separately. This can be done only on towing vehicle systems where the trailer can be supplied air while the parking brakes of the towing vehicle are released. Spring brakes can be tested by gently applying engine power in a low gear while the brakes are applied. The vehicle may rock slightly but the wheels should not turn during the test.
Failure of the spring brakes to hold the vehicle stationary indicates defective spring brakes.
- Apply the spring brakes on the vehicle to be tested and remove wheel chocks.
- Gently apply engine power in a low gear.
- Observe the vehicle’s response. The vehicle may rock and shake and the wheels may move slightly, but there should be no significant movement of the vehicle.
The vehicle passes the test if the spring brakes hold the vehicle in place.
The vehicle fails the test if the spring brakes do not hold the vehicle in place.
Important: The Ontario Highway Traffic Act and regulations prohibit the operation of a vehicle with defective spring brakes.