Service brake accelerator for rail vehicle air brake systems

Claim 1

A pulsating device brake accelerator for rail vehicle air brake systems, said accelerator cyclically venting air from a main air supply to atmosphere, and returning to a neutral position between its working cycles and at the end of a brake line pressure drop, said accelerator comprising (a) a first movable abutment (5) subject to the pressure in a line chamber (3) connected to a main air supply (1), and, against the force of a spring (10), to the pressure in a reference pressure chamber (6) connected to said main air supply through a nozzle (7); (b) said first movable abutment, upon application of overbalancing pressure, effecting the opening of a first valve means (5, 9) in a connection, through a first choke (23), between said reference pressure chamber and a first chamber (24) bounded by a valve seat (20); (c) a second movable abutment (17) seatable upon said valve seat under pressure of a spring (21) so as to close said valve seat, and forming a second valve means (17, 20) in combination with said valve seat; (d) a second chamber (16) separated from said first chamber by said valve seat, said second chamber being in continuous communication with atmosphere through a ventilation channel (26) with a second choke (25); (e) a channel (15) with a third choke (14), connecting said main air supply with atmosphere, through a shut-off valve (12, 13) adapted to be opened laggingly after one of said valve means by a said movable abutment; (f) said shut-off valve (12, 13) being disposed for opening by said first movable abutment (5) laggingly after said first valve means (5, 9); (g) said channel (15) terminating in said second chamber (16).