Patent GB-1005598-A (GB)
Title: Improvements in vehicle brakes
IPC: B21K1/04
Filed: 1962-07-11
Abstract: 1,005,598. Fluid pressure braking systems; couplings. ROBERT BOSCH G.m.b.H. July 11, 1962 [July 14, 1961], No. 26610/62. Headings F2F and F2G. In a fluid pressure braking system for tractor-trailer vehicles having supply and control conduits leading to the trailer and connected to the tractor by disengageable couplings, each coupling head part on the tractor has a self-closing valve and, in addition, the coupling head for the control conduit includes a valve operable in conjunction with the self-closing valve for disconnecting the pressure supply on the tractor from the other coupling head. As shown, compressed air is supplied by a main reservoir 2 on the tractor to a driver's valve 3, which applies the tractor brake 4 directly and feeds control conduit 5 connected by coupling 6, 7 to a relay valve 8 on the trailer, and a supply conduit 11 also leads from the main reservoir via a valve in the coupling head 6 and coupling 12, 13 to a pressure safety valve 14 on the trailer, and thence to trailer reservoir 9 for applying the trailer brakes 10 under control of the relay valve 8. The coupling heads 6 and 12 each have a self-closing valve so that if either coupling breaks pressure is retained in the tractor but, in addition head 6 includes a valve operating conjointly with the self-closing valve and which is normally open to connect the portion 11a of the supply conduit with the tractor portion 11, but which upon disengagement of the coupling 6, 7 closes the connection between conduits 11 and 11a and also reduces the pressure in or vents the conduit 11a so that if coupling 12, 13 remains intact the pressure in reservoir 9 drops to a value set by valve 14 to cause valve 8 to apply the trailer brakes as if coupling 12, 13 were also disconnected. In one construction of the coupling head 6, Fig. 3, the self-closing valve is formed by a sleeve 18 including a valve seat 29 and containing a valve plate 28 urged into contact with the seat 29 by a relatively strong spring 26. The valve plate 28 is secured to a stem 30 having a flange 32, acted on by a relatively weak spring 34 in a chamber 16 connected with conduit 5, and a cylindrical portion 37 operating in a bore 40 and provided with seals 38, 39 engaging the bore. The portion 37 includes passages 41, 42, the former registering with a vent opening 44. The upper end of portion 37 is tapered to provide an annular space communicating with conduit 11a via part 45 and is spaced from a valve plate 47 when the coupling is disengaged, so that the valve plate 47 is held down against a seat 49 by a spring 50 to close off an inlet for conduit 11, formed in a plug 51, and air is exhausted from the conduit 11a via the vent opening 44. When the coupling element 7 is connected to the head 6, sleeve 18 is pushed inwards, first compressing the weak spring 34 so that flange 35 abuts the casing and valve plate 47 is lifted by the upper end of stem portion 37, and then compressing the stronger spring 26 so that valve plate 28 is also moved off seat 29, interconnecting conduits 11, 11a and also allowing air to flow from the conduit 5 into the coupling element 7 and thence to the trailer. Coupling head 12 for the supply conduit has a self-closing valve only, this being formed by a sleeve containing a spring similar to sleeve 18 and spring 26, the spring, however, acting between the sleeve and a fixed valve plate. In a second construction of the head 6, Fig. 5, a sleeve 63 moved inwardly by connecting coupling element 7 is provided with seals 68, 69 and a recess 70 so as to act as a slide valve connecting conduits 11, 11a when the element 7 is connected and venting conduit 11a to the control conduit when element 7 is disengaged, as shown. A stem 76 carried by the perforated upper end of sleeve 63 carries a valve plate 57 acted on by spring 59 to close off the conduit 5 when element 7 is disconnected, as shown, engagement of element 7 lifting the valve plate 57 to connect conduit 5 with the coupling element 7.