Patent GB-839005-A (GB)
Title: For detecting speed differences between rotatable members
Inventor: WILSON ROSSER L
IPC: B60L3/10
Filed: 1956-08-27
Abstract: 839,005. Electric synchronous movements. AMERICAN BRAKE SHOE CO. Aug. 27, 1956, No. 26140/56. Class 40 (3). [Also in Group XXXV] Apparatus for detecting an objectionable speed difference between a pair of independently-rotatable members comprises a pair of commutator switches having corresponding commutator segments electrically interconnected, rotor members adapted to be driven from the said members, one of said commutator switches having a single master brush element and the other having first and second brush elements angularly spaced from each other, a slow-release relay having a single normally open pair of relay contacts, an energizing circuit for said relay including said single master brush element and said first brush element and a detecting circuit including said single master brush element, said second brush element and said relay contacts. In the arrangement shown, comprising two units 21, 22 of three commutators 21-1 ... 21-3, 22-1 ... 22-3 secured to three axles, all of which may be motor-driven from a generator G20, the master or central commutators 21-2, 22-2 have brushes 21M, 22M engaging segments 24 of which diametrically-opposite members are connected by conductors 25, and alternate segments are connected by conductors 27A, 27B and 27X, 27Y to corresponding alternate segments of the commutators 21-1, 21-3 and 22-1, 22-3 of the two units. The subsidiary commutators, such as 21-1, have 24 segments of which the diametrically-opposite members are connected by conductors 25, one only of which is shown, and which are engaged by brushes such as 26A, 26A-1 with an angular spacing of approximately 90 degrees. Connections from the brushes 26A, 21M complete an energizing circuit for a relay A, and brushes 26A-1, 21M extend a circuit over the winding of a relay C to a contact engaged by the operated contact A-1 of the relay A. Relays B, X, Y associated with subsidiary commutators 21-3, 22-1, 22-3 are similar to the relay A, and these relays have a delayed release effected by resistance capacitor circuits 60 connected to their windings. The arrangement is such that if there is a predetermined relative phase difference between the master commutator and a subsidiary commutator, the relay A has released before the circuit through the relay C to the contact A-1 has been set up by brushes such as 26A-1, 21M so that relay C is not operated. If, however, the relative phase difference is greater or less than the prescribed value the relay A will not have released when the brushes 26A-1, 21M extend the circuit to the contact A-1, and over this operated contact-member a circuit will be completed for the relay C, which has a delayed release effected by a C, R circuit 60. In the normal operation of the power plant, the operation of the switch T-1 by the throttle T energizes relay SH which at contacts SH1, SH2 short-circuits field winding R1 and at contact SH3 operates relay BF which at contact BF-1 cuts in the exciting winding of the generator G. The operation of relay C energizes relay ABS which at contact ABS-1 shunts the winding of the relay SH, which releases, and at contact ABS2 completes the circuit for a signal lamp L-2. Also over contact C2, contact 53, and contact member P1 of normally-operated relay P, a circuit is completed for an indicator lamp L1 of a control panel 50. If relay C is held operated for a prescribed period, for example by repeated energization within its release periods, a relay coil 51C is energized to open a latching contact 51 which remains in the open position until reset manually. Opened contact 51 opens the circuit of relay P which releases, temporarily extinguishes lamp L-1 and then over contact 55 engaged by released armature P1 completes a permanent circuit to the lamp L-1. Over contact 56 engaged by the released armature P2, a circuit is completed for relay AL which at contact AL-1 completes another circuit for relay ABS and also a circuit for an audible alarm 95. The blowing of one or both of the fuses 62, 90 results in the release of relay P which effects the continuous illumination of the lamp L-1 and the operation of relay AL which at contact AL-1 operates relay ABS- not in this case controlled by relay C-to release relays SH and BF and reduce the power supplied to the motors from the generator G. In a modification, Fig. 2 (not shown), the relay AL is eliminated, the relay ABS is energized solely under control of relay C and the alarm 95 is operated by the release of relay P. In a further modification, Fig. 3 (not shown), the relay AL and alarm 95 are eliminated, the relay ABS is operated by the operated contact of relay C or the released contact of relay P and the lamp L2 is lighted by an operated contact of relay ABS, as in Fig. 1. In a further arrangement, Fig. 4 (not shown), a rectifier included in the operating circuit of the relay ABS and located between the connections from the contact engaged by the operated armature of relay C and from the released armature of relay P fulfils the function of the relay AL of Fig. 1. In a modified arrangement, Fig. 5 (not shown), a single master commutator is used for a number of subsidiary commutators associated with separate groups of axle assemblies. The subsidiary commutators of the groups are connected respectively to the odd and even segments of the master commutator, and appropriately poled rectifiers are included in the connections between the conductors from the master commutator and the segments of the similarlyconnected subsidiary commutators. Specifications 634,633, 641,625, 839,006 and U.S.A. Specifications 2,232,752, 2,232,753, 2,232,896 and 2,335,984 are referred to.