How It Works

Electronic Brake Systems

Electronic Cab Controllers

The Electronic Brake Controllers fall into 3 main category’s

·  Time Based Controllers  

·  Inertia Based Controllers

·  Proportional Controllers

The Time Based Controller is considered the low end but popular and reliable solution to the braking question. It takes an electrical input from the brake light switch in the vehicle and  ramps up the output voltage offering a smooth even progressive braking action as the brakes are applied. Usually there is adjustment for how fast and how aggressive the braking action is applied ( gain , max ). This is generally the least expensive solution for cab control of electric brake or electronic control over hydraulic brakes.

The Inertia Controller comes in two types Pendulum and Accelerometer.  Both function alike.
As the brakes apply on the towing vehicle the pendulum swings forward and the controller sends more voltage to the trailer brake actuator.The accelerometer now converted to a decel function does the same thing but it is all solid state and possibly more accurate. These units may well be position sensitive and require orientation and leveling for best operation.

Proportional Controllers are a cut above inertia style units in that they may do more system monitoring and measure tow vehicle stopping force to geater degree.  They may include inertia function also and the advanced accelerometer read out for decelerations makes for smoother and faster applications than some previous controllers.  They may have digital displays,  harness hookup and some self adjustment with advanced diagnostics.

The True Proportional Controllers come in two types as well and are perhaps a fourth category for controlling trailer brakes electronically.  The Ford Tow Command and the Sensabrake EVO are good examples of true proportional control. The Tow Command or a system integrated with the tow vehicle as original equipment utilizes actual towing vehicle hydraulic brake pressure to provide the signal to the brake controller. This transducer signal is then conditioned and sent to the brake actuator as a 0-12 volt output.
The EVO by SensaBRAKE uses a pad that replaces the rubber on the brake pedal of the towing vehicle. Contained in the pad are strain gauges that provide a signal that is proportional to the force applied to the brake pedal. The electronics then translate this to a 0-12 volt output for the actuator. Read out with trailer monitoring is included.

The Radio Frequency and Control Carrier Multiplex Controllers (wireless, cigar lighter control pendants) provide another way for the controller to communicate with the trailer brake actuator.  They offer proportional control and accelerator digital features with wireless hookup simplicity---they require trailer breakaway battery kit and require this battery to be capable of powering the service brake application. These units work only with their own trailer brake actuators .


Please do not use this primer as a substitute for the manufacturers recommendations and service manual