Acronyms that contain the term overrun brake 

Overrun brake

An overrun brake (called a surge brake when invented) is a brake system commonly used on small trailers, where the motion of the trailer with respect to the towing vehicle is used to actuate the brake. The early systems were fitted with a spring system which was not very effective. Later systems were fitted with a sliding mechanism within the coupling, which enables the drawbar to move back and forth relative to the trailer chassis. When the towing vehicle brakes, the inertia of the trailer slides the mechanism, this in turn uses the travel of this mechanism to pull on the brake rod which applies the brakes. The sliding mechanism contains a damper to even out the shock loading transmitted from the tow vehicle. Therefore, the inertia of the trailer provides the force to apply the brakes. Some systems have a ball hitch that is normally straight, but when the lead vehicle starts braking, the trailer pushes forward on the ball hitch, pitching it up which then activates a variable hydraulic brake system. Upon activating the trailer slows down pulling back on the hitch again, making it level then that shuts off the braking system. Some systems may also have a switch that disables the system so the brakes won't lock while you're backing up. Other systems take the backup lamp input from the lead vehicle that shuts the system off automatically.

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