Patent GB-1358110-A (GB)
Title: Gas-pressure-operated brake control apparatus
IPC: B60T13/26
Filed: 1972-08-10
Abstract: 1358110 Pneumatic braking systems; relay valves KNORR-BREMSE GmbH 10 Aug 1972 [13 Aug 1971] 37446/72 Heading F2F A compressed air brake system for a vehicle with a trailer comprises a service brake valve 3 operable to control pressure in main control lines 4, 5 connected to service brake cylinders 6, 7 respectively, and an auxiliary brake valve 11 operable to control pressure in an auxiliary line 12 connected to a spring-load brake cylinder 14: the system also includes a trailer brake valve assembly 15 operable to control a trailer brake via a trailer brake control line 24-the assembly 15 is operable by actuation of valves 3 or 11 and continues to function to give trailer braking even if one of the lines 4 or 5 or 12 fails. The valve assembly 15 comprises a double valve 16, 17 of which valve 16 controls the connection of a chamber 18 with atmosphere and valve 17 controls the connection of chamber 18 with a feed chamber 19; the trailer line 24 is connected with chamber 18. The feed chamber 19 has connection with two reservoirs 8, 9 via respective relief valves 20, 22; and the reservoir 8 is connected with auxiliary valve 11 via a pipeline 10 whilst reservoir 9 is connected via pipeline 21 with a trailer supply line 41. The valve assembly 15 also includes a piston 26 controlled by the pressure in a chamber 27 connected to line 5 and movable to actuate the double valve 16, 17. Pistons 32, 43 separate the chamber 27 from a chamber 33 connected with the control line 4, and the chamber 33 is separated by a fixed partition 34 from a chamber 35 connected to the line 12. The chamber 35 is bounded by a piston 31 on the other side of which there is control chamber 36 connected via a passageway 37 containing a throttle 38 with a connection 39 between the pipe-line 10 and the valve assembly 15. The piston 31 has a rod 30 movable to abut a pistonrod 28 of the piston 26. For service braking the valve 3 is actuated whereby lines 4 and 5 are filled from pipe-lines 1 and 2 which are connected to two sources of compressed air and cylinders 6, 7 are actuated: pistons 32, 43 are exposed to at least substantially identical pressures on both sides and are unmoved but piston 26 is moved downwardly to close valve 16, open valve 17 and cause flow to the trailer brake via chambers 18, 19 and line 24. If line 4 fails pistons 32, 43 will be biased upwardly until piston 32 abuts against a stop 45 but piston 26 will still operate the double valve 16, 17; if line 5 fails pistons 43, 32 will be moved downwardly to move piston 26 to actuate double valve 16, 17. For auxiliary braking, valve 11 is actuated to reduce pressure in line 12 and spring-loaded cylinder 14 which is thereby actuated. The pressure in chamber 35 is also decreased which allows the prevailing pressure in chamber 36 to move piston 31 downwardly against a compression spring 10 and bring rods 30, 28 into abutment to move piston 26 and operate double valve 16, 17 to give trailer braking.  Should damage occur during vehicle travel to empty the cylinder 14 whereby the vehicle will be braked: the damage will cause reservoir 8 to empty via valve 11 but pressure in chamber 36 is lost only gradually owing to the presence of throttle 38 in passageway 37. Hence pressure in' chamber 36 predominates over pressure in chamber 35 which is lost immediately and piston 31 is moved downwardly and trailer braking is initiated for a period until chamber 36 loses pressure. The cylinder 14 can thereafter be brought back to its released condition by an emergency device and service braking for both vehicle and trailer is still available. The pistons 32, 43 may be spring-biased apart. The trailer supply line may be connected to a source of compressed air other than pipe-line 21.