Patent GB-908624-A (GB)
Title: Car retarders for railroads
IPC: B61K7/06
Filed: 1960-11-18
Abstract: 908,624. Railway track brakes. GENERAL RAILWAY SIGNAL CO. Nov. 18, 1960 [Dec. 7, 1957], No. 39705/60. Class 103 (1). In a track brake a selectively operable two position toggle locks a retarder in a closed condition wherein the vehicle weight provides the braking force, or allows an open condition wherein the weight produces yield of the retarder to provide substantially no braking effort. The retarder comprises a pair of brake shoes 42, 43, which may be of rail section, secured to beam units 21, 22 pivotally interlocked by a cylindrical bearing portion 23 of beam 21 held within a socket 24 of the beam 22. The outer ends 25, 30 of the beams are of rectangular section and are retained in brackets 27, fixed to ties 16b, and lever arms 32 pivotally mounted on brackets 33 fixed to ties 16c. The lever arms 32 are also normally held in the retarder closed position by toggle members 36, 37 biased to an over-centre position by springs 41. The beams 21, 22 are biased to the closed position by springs 65 acting between the ties 16b and beam 22. Lateral movement of the beams is restrained by ribs 59 engaging the sides of ties 16b, the ties 16b and 16c being secured to two fully-extending ties 16a. The retarder track section TS1 has a continuous rail 11a and a guard rail 19 mounted on crossties 16, 17, 18 on one side, and retarder rail sections 12a extending from the normal rail 12 to, and between, the centres of the beam units BU. The ties 16, 17, 18 are held in spaced relationship by bars 60. Flat ledge portions 53 of the beams 21 support the rail sections 12a which are held by lugs 54 and angle wedges 55, rail anchors 56 (not shown) preventing lateral movement of the rails. A channelsection resting block 29 is provided on the ties 16b for the beam 21 in the open condition. The toggle 36, 37 can be moved from the overcentre position by a wedge 71, actuated by screw and nut mechanism 77, 76 driven from motor M, bearing on a projection 73 on the toggle 37 to place the retarder in the open condition. Limit switches L, R are provided in the motor circuit allow selection by manual switch of either closed or open conditions. In the closed condition, the toggles 36, 37 are in the over-centre state and, together with the springs 65, tends to raise the beams 21, 22 and rail sections 12a clear of the blocks 29. As a vehicle wheel enters the retarder, the shoes 42, 43 are spread by the wheel and cause the beam units to pivot at their centres and rise from the blocks 29, the beams 21, 22 moving transversely to centre the shoes evenly on the sides of the wheel. The weight of the vehicle then acts on the rail sections 12a to force them down and cause the brakes 42, 43 to grip the wheels, with the beams still suspended above the tie bed. Actuation of the motor M to force the toggle 36, 37 to a collapsed non- rigid position releases the rigid support for the end of the beam 22, allowing the beams 21, 22 to sink to rest on the block 29 and reduce the braking pressure to substantially nil. Wear adjustment for the brake shoes is provided by shims 52 between the beam 22 and shoesecuring bracket 48. Reference has been directed by the Comptroller to Specification 866,953.