How Does a Pendulum in a Brake Controller Work?

When a vehicle towing a trailer is forced to slow down or stop, the trailer must also stop or else slam into the back of the towing vehicle. The trailer, which is dependent on the towing vehicle for power, may have difficulty stopping effectively when the towing vehicle brakes, due to the forward momentum of the trailer. For this reason, brake controllers are installed. Brake controllers manage the speed of the trailer in relation to the towing vehicle. There are various types of brake controllers available for towing vehicles, including proportional brake controllers.

Proportional brake controllers, also known as pendulum brake controllers, use a pendulum to detect changes in the tow vehicle's speed. The brake controller can then use this information to adjust the trailer's speed, and match it to the towing vehicle's speed. Since the trailer's speed changes in proportion to the towing vehicle's speed, these are called proportional brake controllers.

After being installed, the pendulum in a proportional brake controller must be calibrated before being used. This allows the pendulum, which is a motion-sensing device, to synchronize with the motion of the towing vehicle. In this process, the pendulum is adjusted while in place on a flat surface, to ensure that it is pointing straight downward. It should also be tested to ensure that it moves freely with the motion of the vehicle.

When on a perfectly level surface, the pendulum in a brake controller is pointing down. As the towing vehicle moves forward, the pendulum swings toward the back of the vehicle. As soon as the momentum of the vehicle stops due to a braking action, the pendulum swings forward. The arc of the pendulum's swing is measured, and used to calculate the amount of braking necessary for the trailer. Due to the pendulum's action, it works best when used in areas without large hills.