Orscheln® Trailer Parking Brake Systems feature a mechanical break-away feature that will engage the trailer brakes automatically if the towed vehicle becomes unhooked during transportation. The lockable over-center lever prevents any unauthorized person from moving the trailer once the system is engaged and locked.
Air brakes are used in trucks, buses, trailers and semi-trailers. This is the preferred type of braking system for these vehicles for several reasons. First, the use of air allows multiple vehicle units to be coupled so that all units have braking capability and so that all of those units' brakes may be controlled from the cab. Coupling would be infeasible if a liquid were used as the mode of transmission of force, as it is in hydraulic brakes. In addition, the use of an air brake system allows for the incorporation of an emergency braking system that utilizes parts of the service brake and parking brake systems. Emergency braking systems are required on all semi-trailers by CFR 49 393.43, as it states "Every motor vehicle, if used to tow a trailer equipped with brakes, shall be equipped with a means for providing that in the case of a breakaway of the trailer, the service brakes on the towing vehicle will be capable of stopping the towing vehicle."
Air brake systems are three braking systems combined:
ZF TRW is the leading supplier of advanced parking brake systems worldwide and was first-to-market with its Electric Park Brake (EPB) on a mass production vehicle in 2001. There are more than 15 million ZF TRW EPB calipers on world roadways today.
In the US, for example, future vehicles will require rear backup cameras to help prevent accidents where cars reverse into children playing on driveways (FMVSS 111). An electric park brake system could be integrated with the video signal and automatically brake the vehicle if a potential issue is detected.