Patent GB-1212050-A (GB)
Title: Relay valve unit for brake systems or the like
Inventor: MANN TORSTEN LARS TEODOR
IPC: B60T8/18
Filed: 1968-10-24
Abstract: 1,212,050. Load-responsive fluid-pressure brakes. T. L. T. MANN. 24 Oct., 1968 [25 Oct., 1967], No. 50606/68. Heading F2F. A pressure fluid feed regulator, for fluidoperated brakes, and having variable characteristics dependent on the position of an adjusting member movable in response to the load carried by the vehicle, the adjusting member comprising a displaceable fulcrum for a rocker member resembling a balance beam, the regulator also including a valve device, is characterized in that the rocker member is carried by and secured to a diaphragm which is deflectable to impart mobility to the rocker member and which forms one of two pressure-chamber-confining walls. As shown in Fig. 1, an operating pressure air supply is connected at F, the conduit for the brake cylinders at C, and a control pressure supply at S. An adjusting member 6 is slidable in and out of the housing H by mechanism which senses the vehicle load. The movement of member 6 is in a radial relation to a disc 2 (in this case circular) mounted centrally in a circular diaphragm 1. The disc 2 constitutes the rocker member resembling a balance beam, and rollers 7 on member 6 constitute the fulcrum for the disc. The brake cylinder pressure is conveyed from connection C to the pressure chamber 4 under diaphragm 1 via a passage 5 and a hole in the diaphragm. In the position shown (brakes off), the connection C also communicates with the atmosphere via an opening 11 in a partition in the housing, the region above diaphragm 1, and an aperture A. The disc 2 is urged upwards by an eccentrically-placed compression spring 3, and upward movements of the disc are transmitted by an actuating rod 10 to a stem-like portion 13 of a waisted piston 14. The outside of the portion 13 is engageable in the opening 11 to close it. The connections F and S are put into communication with each other, whereby the maximum available pressure at F at any time corresponds to the control pressure at S, both pressures being regulated by a separate regulating valve (not shown or described). In operation, when control pressure is applied at S, piston 14 descends, whereupon connection C is first cut off from the atmosphere by closing of the opening 11, and then connection C, and with it the pressure chamber 4, is connected to the air supply at F to apply the brakes. Heavier loads on the vehicle cause movement of member 6 inwards, in consequence of which the effect of pressure in chamber 4 decreases, and a correspondingly smaller pressure at S is needed to force piston 14 downwards. The connection F may be dispensed with, in which case seal 16 is omitted, and the top of piston 14 is shaped to permit pressure fluid from connection S to reach the brake connection C when required. For application to trailer brakes, the top of housing H is modified in the manner shown in Fig. 5. Connection S normally communicates with pressure chamber 15 above piston 14 by an inlet 32. An emergency brake piston N is normally held to the right by fluid pressure applied at a further connection M, the conduit feeding M serving also to replenish continuously a separate reservoir carried on the trailer. If the trailer should break loose, or be intentionally separated, from the tractor vehicle, in consequence of which the pressure fails at connection M, spring 30 pushes piston N to the left. The piston thereby closes connection S, and a waist portion 31 provides communication between inlet 32 and a passage 33 provided in the housing H; this passage communicates with connection F, so the piston is forced downwards and the brake is applied. In Fig. 3 the diaphragm 1<SP>1</SP> carrying the rocker member 2<SP>1</SP> is actuated, instead, directly by the control pressure supplied at S. The rocker member or disc 2<SP>1</SP> in this case is urged away from the fulcrum 7<SP>1</SP> by the eccentrically-placed spring 21, and the spring is closely associated with the valve assembly. The "fulcrum space" on one side of the diaphragm communicates with the atmosphere via aperture A, as before, and brake connection C communicates with the fulcrum space, and hence with the atmosphere, in the "brakes off" position shown. In operation, on application of pressure at S, the central portion 22 of pin 10<SP>1</SP> engages the top of valve body 23, and then pin 10<SP>1</SP> and valve 23 move downwards together to connect C with F. Fig. 4 is a modification of Fig. 3 which incorporates an emergency brake piston N similar to that in Fig. 5 except that in this ease spring 30 is replaced by the operating pressure F. While pressure prevails at M, piston N is in its uppermost position (not as shown), and forms part of, and moves with, pin 10<SP>1</SP>, 22. For this modification a separate opening to atmosphere, 27 (instead of A), is used during normal working. If there is loss of pressure at M due to trailer disconnection or breakaway, pressure from connection F finds its way upwards through the body of piston N, depressing it to the position shown, where atmosphere connection 27 is closed, and F communicates with C, so the brakes are on, despite the "up" position of pin 10<SP>1</SP>, 22.