Patent GB-1080214-A (GB)
Title: Improvements in or relating to safety apparatus for two-line compressed air brake installations
IPC: B60T13/40
Filed: 1964-09-28
Abstract: 1,080,214. Fluid-pressure brakes. KNORRBREMSE G.m.b.H. Sept. 28, 1964 [Sept. 26, 1963], No. 39489/64. Heading F2F. In a compressed-air system for a tractortrailer vehicle of the kind having provision for automatic operation of the trailer brakes by an auxiliary reservoir on the trailer under the control of a supply pipe 19 and a brake pipe 21 on the tractor which are connected with the trailer via coupling heads 15, 17, means is provided for conserving air in the tractor part of the system if either one or both of the coupling heads should become separated from the corresponding trailer coupling heads (not shown) comprising the provision of a relay valve 7 including a control piston 53 which is initially maintained in a lower position by spring biasing, to cause the pipes 19, 21 to be cut off from the tractor reservoir 1, and which is urged upwardly by air from the reservoir 1 through seriesconnected valves 25 associated with the coupling heads 15, 17 only when both of these heads are coupled with the trailer coupling heads, for which purpose the valves 25 are arranged to be opened by pins 29 co-operating with the coupling heads on the trailer. In the arrangement of Fig. 1 the brake pipe 21 is arranged to be fed via a driver's valve 9, for the tractor brake cylinders 13, and a valve 61, 63 controlled by the piston 53 via a valveoperating sleeve 59, the latter also operating a second valve 71, 77 for controlling the supply of air from reservoir 1 to the supply pipe 19. When either one or both coupling heads 15, 17 become separated from the trailer couplings one or both pins 19 are urged downwards by a respective spring 27 to the position shown in which the corresponding valve element 35 is closed on a seat 39 and an atmosphere connection 31 is opened to the control piston chamber 49, either direct in the case of one coupling head or via interconnecting pipe 45 in the case of the other coupling head. This causes the reservoir 1 and driver's valve 9 to be cut off from the pipes 19, 21, respectively, and these pipes to be interconnected via the interior of the sleeve 59. The resultant pressure rise in pipe 21 or pressure reduction in pipe 19 causes an immediate application of the trailer brakes via the usual relay valve on the trailer (not shown). In the arrangement of Fig. 2 a relay valve 81 of known type is used to control pressure in the brake pipe 21 in correspondence with that in the tractor brake cylinders 13 by connecting the driver's valve 9 to the control chamber of this relay valve, control being effected via valve structure 83, 85, 87. The relay valve 7 is therefore simplified and incorporated with the relay valve 81 whereby control piston 53 operates a single valve element 101 via sleeve 95 to open valve 101, 107 and close valve 101, 105 when both heads 15, 17 are coupled, and to close valve 101, 107 and open valve 101, 105 when one or both heads 15, 17 are uncoupled, so that in the latter case pipes 19, 21 are cut off from the reservoir 1 and are interconnected via the sleeve 95.