Patent GB-903435-A (GB)
Title: Improvements relating to the control of retarders in a hump yard
Inventor: NEW WILLIAM ERNEST
IPC: B61K7/12
Filed: 1958-06-13
Abstract: 903,435. Control apparatus for hump yard retarders. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. April 17, 1959 [June 13, 1958], No. 18958/58. Class 105. Automatic control apparatus for a hump yard retarder includes means for measuring the rolling resistance of each cut in the form of a D.C. voltage, and means to compare this voltage with a series of D.C. reference voltages until substantial parity with a reference voltage is reached and to provide an output determined in dependence on this reference voltage to select a leaving speed for the cut from the retarder. General.-A rollability discriminator comprises a storage amplifier 1, voltage comparator 3 and two cascades of relays RD2, RD4 ... RDN-1 and RD1, RD3... RDN connected so that the picking up of an odd relay prepares a pick-up circuit for the next relay in sequence in the even cascade and vice versa, the relays, except RD1, having slow pick-up characteristics. Contacts RD1(4), RD2(3) ... RDN(3) of the chain relay connect one or other of variable resistors RV1 ... RVN in series with a common connection between a potentiometer 11 and a reference voltage input 8 of comparator 3, the resistors RV1 ... RVN decreasing progressively and normally, at rest, resistor RV is connected to establish a test voltage at 8. A second comparator input 7 receives from amplifier output 6 a voltage representing the cut rolling resistance, and a relay CK remains energized provided voltage at 8 exceeds that at 7. At rest, storage amplifier 1, including an amplifier 2, has its input 5 connected via ST(1) of start relay ST, to potentiometer 10 for a test input; relay H is de-energized or completes a charging. circuit for condenser C from 5 via H(1), R1, C, H(3) and R2; further with H de-energized, amplifier 2 is short-circuited via H(3) and H(2), and output 6 is earthed, hence voltage at 8 is greater than at 7 to maintain CK energized. Relays T1R, T2R, T3R, controlling contacts T1P, T2P, T3P, are picked up in sequence as cut moves through track sections T1, T2, T3 approaching the retarder, these relays with relay TCP control an auxiliary relay TR, relay TCP detecting when section T1 has been cleared. Cut in T1.-Relays TIP and TR are picked up and TCP released. Relay H is energized via T1P(1), TR(1), ST(2) to start a checking sequence of amplifier 1 and comparator 3, a voltage is supplied to 7 from condenser C, in excess of that at 8 to check that relay CK releases; start relay ST is picked up via T1P(1),  TR(1) and CK(3) to complete the check. Picking up of ST breaks the energizing circuit of H at ST (2), applies a rolling resistance voltage, from, for example, radar apparatus, to input 5 via ST(1), completes its own stick circuit via ST(4), and prepares a stick circuit for the first chain relay RD1 at ST(5). Release of H charges condenser C to voltage at 5, short-circuits amplifier 2 and earths output 6, relay CK being therefore picked up. Cut in T2.-Relay TR is released. to pick up relay RD1 via ST(5) and back contact TR(1); H is picked up via front contact RD1(1) to discharge condenser C to terminals 6 and 7. Resistor RV1 is connected to input 8 via front contact RD1(4) to compare the rolling resistance voltage with the highest reference voltage. If voltage at 8 is greater than at 7, CK remains energized and after a delay relay RD2 is picked up via T2P(1), back contact TR(1), ST(5), RD1(2), H(4), front contact CK(1), back contact RDN-2(1) in series with the back contacts of the other chain relay. A stick circuit is completed for RD2 at RD2(2) and the closing of contact RD2(3) replaces RV1 with RV2 to reduce the reference voltage at 8. Closing of RD2(1) completes a pick-up circuit for relay RD3 via T2P(1), TR(1), ST(5), RD1(2), H(4), CK (2), and RDN-1(1) and back contacts (1) of the relays of the even cascade in series. Should voltage at 8 still exceed that at 7, CK remains energized and relay RD3 is picked up after a delay to complete a pick-up circuit for RD4, a stick circuit for itself and substitutes the next resistor for RV2 to again reduce the voltage at input 8. The stepping action of the relay chain continues until voltage at 8 is reduced to just below that at 7, CK is then released and at its back contacts CK(1), CK(2) it opens the remaining chain relays and closes a circuit for network 9 having outputs A, B, C, D which are energized in a code combination determined by the chain relays still held energized, via contacts not shown; this code is supplied to the retarder control apparatus to select a leaving speed. Cut in R3 immediately preceding the retarder, back contact T3P(1) opens to break the energizing circuits of ST and H to release relays of the chain and set the discriminator at rest. Specifications 676,731, 853,908 and 903,436 are referred to. Reference has been directed by the Comptroller to Specification 781,904.