Patent GB-919697-A (GB)
Title: Multiple section retarder for railway vehicles
IPC: B61L17/02
Filed: 1959-05-01
Abstract: 919,697. Railway retarder systems. WESTINGHOUSE AIR BRAKE CO. May 1, 1959 [May 2, 1958], No. 14914/59. Addition to 910,989. Class 105. In an improvement in the multiple section retarder for controlling the speeds of cuts of one or more railway vehicles passing therethrough in a railway hump marshalling yard as claimed in the parent Specification, the control system of the group retarders 1-2GR1T, 1-2GR2T is largely the same as that disclosed in the parent Specification (Fig. 1b being a continuation of Fig. 1a) but provision is made for the introduction of a differential pressure unit DPU constituted by two mechanically linked pressuresensitive devices 7, 8; one of these devices being provided for each section of the double section group retarder 1-2GR1T, 1-2GR2T such that a smooth transition of the cuts is made from one to the next of the retarder sections and when the cut occupies both the retarder sections, the speed control for one section is provided from the control means of the preceding retarder section. The first section of the group retarder 1-2GR1T controls the speed of a cut of wagons after it leaves the primary retarder according to the weight and speed of the cut. The control may be either automatic or manual according to the setting of lever RIMC. The control of the second section of the group retarder 1-2GR2T may also be either automatic or manual according to the setting of lever R2MC. Bourdon tube 5 is set to control the actuating cylinders of the retarder control 1-2GR1 between 64-59 p.s.i. for medium weight cuts and also provide a stand-by pressure in the first retarder section when the latter is unoccupied. Bourdon tube 6 is set to control the actuating cylinders of the retarder control 1-2GR1 between 39 and 32 p.s.i. for lightweight cuts. For heavy cuts, the relay RIH in storage unit 1-2GR1-ESU is energized and relay RLI is released and the pressure in the first section 1-2GR1T is preset to the existing full pressure of the fluid pressure source. When the first section of the group retarder is on stand-by pressure or is preset to one of its pressure ranges as described above, the second section remains at the pressure to which it was last controlled by the passage of a cut. The differential pressure unit DPU presets the second section of the group retarder to a pressure within 4 p.s.i. of that of the first section by Bourdon tubes 7, 8 of the unit acting on movable contact LK of the unit whereby to enable the smooth transition of the cuts from one to the next of the retarder sections. Bourdon tube 7 and 8 are connected by conduits 11a, 11b respectively to the intake manifold of the first and second section respectively of the retarder. Bourdon tube 10 operates to maintain the pressure of the second section of the retarder at 39-32 p.s.i. for light cuts, both sections of the retarder being maintained at their stand-by conditions when unoccupied with the first section maintained between 59-64 p.s.i. by Bourdon tube 5 and the second section remaining at the pressure to which it was last controlled. Reference has been directed by the Comptroller to Specifications 746,443, 781,904 and 811,821.