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(last edited July 20, 2005) Front Page | Recent Changes | Title Index | User Preferences | Random Page | HelpA system for automatically applying a parking brake to a vehicle when the automatic air brake pressure is not available. Manually operated parking brakes can be forgotten by the crew - forgetting to apply them (or enough of them) when stabling a train or forgetting to release them before moving a train. The latter is a common problem which causes wheels to be dragged and damaged by flats.
The spring applied parking brake attempts to overcome these problems.
The principle of operation is that the brake is held released by air pressure and is applied by a spring when the pressure is lost. It acts in the opposite way to the air brake. There are also remotely applied spring parking brake systems available, which can be activated from a push button in the driver's cab. Quite why this complication is necessary escapes me but some railway administrations insist on it.
