MOT
Roller brake test
Also known as: RBT, brake roller test
Measurement of the braking force at each wheel using rollers in the test bay floor. The primary method of brake testing in the MOT.
The vehicle is driven onto the rollers, which rotate the wheel at low speed. The tester applies the service brake and the equipment measures the force at each wheel. The service brake must achieve a minimum overall efficiency (typically 50% for cars), and the parking brake a separate minimum (typically 16%).
Brake imbalance across the same axle is a fail above defined thresholds. A decelerometer is used where a roller test is not appropriate, such as some 4WD vehicles.