It is widely assumed that trailer spring brakes are applied simply by disconnecting the red (emergency) line and that the park button does nothing more than this. Not only is this assumption about the so-called fail-safe nature of trailer brakes technically inaccurate, it could prove positively dangerous at the time a trailer is re-coupled.

The Pownall trailer park valve can be manually operated at any time and does not prevent or relieve drivers of their duty to follow safe working practices. However, should the driver forget, the Pownall safety park valve automatically sets, acting as a safety backup.

This pull to park valve is available factory fitted to new trailers by all leading manufacturers. Fleet users include Sainsbury's, Tesco, Waitrose, Asda and many other blue-chip companies.