GB1328913A - Brake control apparatus for rail vehicles - Google Patents

Abstract

1328913 Fluid pressure systems for rail vehicles KNORR-BREMSE GmbH 19 April 1971 [2 April 1970] 26391/71 Headings F2E and F2F [Also in Division B7] A pressurized fluid brake system for a rail vehicle has a brake control valve 3 responsive to a drop in pressure in a train pipe 1 to cause introduction of an anticipatory braking pressure from an auxiliary reservoir 5 into a pipe conduit 6. The anticipatory braking pressure controls a pressure transmitter 7 but the transmitter 7 is also responsive to the pressure in a pipe conduit 13 which pressure is proportional to the vehicle loading, and the pressure transmitter 7 selectively transmits pressure to pipe conduits 9, 11 which are respectively connected to a no-load brake cylinder 10 and a load brake cylinder 12. With a constant anticipatory braking pressure the pressure transmitter 7 introduces into the pipe conduit 9, in the load range from zero-loading up to a predetermined medium loading L/2, pressurized fluid which rises from a minimum value P min to a maximum value P max , but when the medium loading L/2 is reached the pressure transmitter 7 then lowers the pressure in the pipe conduit 9 to the value P min and, with increased vehicle loading, starts to introduce into the pipe conduits 9 and 11 fluid at an increasing pressure which reaches the maximum value P max at maximum vehicle loading L max . Thus up to medium loading only the no-load brake cylinder 10 has compressed air admitted to it, but when the medium loading is exceeded compressed air is also admitted to the load brake cylinder 12. The no-load cylinder 10 incorporates a piston 20 with a piston-rod 22 which is pivoted on a brake lever 23, and the piston 20 is movable to cause the lever 23 apply to a shoe 27 to a disc 29: a drawbar 24 connects the lever 23 to a lever 25 pivoted by means of a bearing block 26 on the cylinder 12 and actuating movement of the lever 23 causes a shoe 28 on lever 25 to be brought into contact with the disc 29. The cylinder 12 includes a piston 16 with a piston rod 17 which is provided with a plate 19 which is operable to move the piston 20. A pipe conduit 39 connects a cylinder 36 with the pipe conduit 6 and the anticipatory braking pressure in the pipe 6 acts on a piston 35 in the cylinder 36: the piston 35 has a piston rod 34 to which is attached a cleaning block 33 and this cleaning block 33 is movable into engagement with a tread 32 of a vehicle wheel 31. The cleaning block 33 cleans the tread 32 to improve wheelrail adhesion and also acts as a brake shoe, the braking action of which is dependent on the value of the anticipatory brake pressure but is independent of vehicle loading.