Patent GB-933656-A (GB)
IPC: B61L17/02
Abstract: 933,656. Retarder control in railway classification yards. GENERAL RAILWAY SIGNAL CO. June 2, 1961 [Sept. 6, 1960], No. 19962/61. Drawings to Specification. Class 105. In a railway classification yard, the group retarders are automatically controlled in accordance with the distance the cuts of railway cars must travel to their coupling points in the storage tracks. The distance is measured by track fullness detectors of the type described in Specification 933,655 which measure the distance between the entrance to a storage track and the axle of the last vehicle to enter the track. One of these detectors is allocated to a storage track as a cut of vehicles for that track enters the classification system. Where the measured value of track fullness is not available, e.g. when the fullness detector determines that the last vehicle cut to enter the storage track is still in motion, a stored value of track fullness, comprising the fullness value determined for the control of the preceding cut to enter that track minus a count of the number of vehicles in that preceding cut, is supplied for the control of the group retarder. When the destination code for a car cut enters one of the advance storage relay groups of the automatic routing system, a track fullness detector is selected for the associated cut and is connected via a route relay to the designated storage track. The detector interrogates the storage track and sets up in a set of decoding relays a digital representation of the actual distance from the exit of the associated group retarder - to the rear axle of the last vehicle to enter the storage track, in addition, an amplifier in a motion detector circuit stores a voltage which is a function of this distance. The cut is then routed via a hump retarder, where it is initially controlled in accordance with its weight and rolling resistance, to a track circuit preceding the group retarder. On entry into the track circuit, a second route relay operates and again connects the fullness detector to the storage track. If there is no difference between the first and second voltages applied to the motion detector, i.e. if the preceding cut for that storage track has come to a halt, then the actual " distance to coupling " is transferred to a set of counting relays from which it is applied, when the first vehicle of the cut operates a track treadle, to a group retarder release speed computer with a measure of the weight and rolling resistance of the cut. The computer provides a voltage analogue of the release speed which is applied to a voltage store allocated to the cut. The treadle also operates a counting arrangement which decreases the counting relays' registration by the number of vehicles in the cut and the registration is transferred after each vehicle in the cut is counted to a set of counting storage relays allocated to that storage track. When the vehicle cut interrupts a light beam at a point in advance of the retarder, the computed release speed analogue voltage and the cut weight classification are applied to the retarder control circuit and the retarder is positioned to retard the cut sufficiently to ensure its smooth coupling with the cars already in the storage track. Means are also supplied for displaying the track fullness measurement and for enabling the hump operator to reduce the stored value of track fullness.