Power is fed from the tow vehicle's brake lights into the controller. The trailer brakes are activated by a separate heavy-duty circuit through a plug and socket. This allows the brakes to work automatically whenever the tow vehicle's brakes are applied. Properly adjusted controllers can allow the tow vehicle and trailer combination to come to a stop as smoothly as if the tow vehicle were by itself.
Inertia brake controllers are activated whenever the driver depresses the brake pedal. This activates the pendulum circuit, which senses the stopping motion of the tow vehicle. The pendulum circuit applies a proportional amount of voltage to the trailer brakes. The benefits are increased braking efficiency and reduced brake wear.
Proportional controllers send deceleration signal to the pendulum circuit via cable. Like the inertia controllers, the proportional controller offers quick, easy stops. They match the tow vehicle's deceleration rate and apply proportional voltage to the trailer brakes. The controllers are "enabled" by the brake pedal switch. Proportional controllers retains trailer braking power in the event of brake failure in the tow vehicle or a complete loss of traction.
A drawback of the inertia controller is that it will not work whenever the tow vehicle cannot generate enough deceleration. Improperly descending a grade is one good example.
Hydraulic proportional brake controllers do not work well with the anti-lock braking systems of the newer vehicles.
Brake controllers help a driver maintain the safe operation of a vehicle while it is towing a trailer. The inertia and proportional brake controller work well, but they have their drawbacks. An experience driver and well-adjusted brake controller make hauling a trailer a safe endeavor.
