Low-speed roller brake testers are diagnostic instruments used to check the technical condition of car brake systems. They are used to check the effectiveness of brake systems of passenger cars and commercial vehicles. The size of the brake forces is measured on the circumference of the wheels which rotate on the rollers depending on the force expended to the brake pedal. The symmetry of brake forces, braking efficiency and brake booster efficiency are assessed. The parking brake and its effectiveness is also tested.
The car moves its axle between the rollers of the testing device. It stops and shifts neutral gear. The other wheels are blocked against movement in either the hand brake or wedges. Electric motor spins the measuring rollers. The reaction of the drive unit is detected by strain-gauge sensor. The magnitude of this response is proportional to the brake force. Electrical signals are carried to a computer for evaluation. A signalling roller is placed between measuring rollers. It is pressed against the wheel tire by a spring controlling the rotation of the tire. If it is blocked the testing cycle stops automatically.