GB882383A - Systems for detecting the skidding of wheels of railway vehicles - Google Patents

Abstract

882,383. Electric selective signalling systems. FORGES ET ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE JEUMONT. July 22, 1959 [July 24, 1958], No. 25138/59. Class 40 (1). In a system for detecting skidding in railway vehicle wheels, the frequencies of pulse trains, each proportional to the individual speeds of the wheels, are compared with each other and also with the frequency of a further pulse train representing the absolute speed of the vehicle and produced by a magnetic recording and receiving device co-operating with the track. In a first embodiment, Fig. 1, an oscillator 1 feeds A.C. through modulators 2, 3 controlled by the respective driving wheels, and two-state devices 6, 7 to a frequency comparator 80 which also receives a further signal, at a frequency proportional to the absolute speed of the vehicle, from a magnetic recording and pick-up device 9 ... 11 co-operating with the track 12. This device may be of the type described in Specification 818,782. A head 9 records a magnetic signal on the rail which is subsequently picked up by a head 10; when a further head 11 picks up the signal it causes the head 9 to record a new signal, and so on. The device is not effective when the vehicle is travelling slowly. The modulators 2, 3 may each comprise a stationary cored inductor the impedance of which is varied by teeth or like projections moving with each driving wheel (Figs. 2 and 3, not shown). In another embodiment counters are used instead of a frequency comparator. Four wheelcontrolled modulators 2 ... 5, Fig. 4, supply, via two-state devices 6 ... 9, counters 15 ... 18, each of which can count to 31 before returning to zero; they are also zeroized by signals appearing on line 19 or line 20. If any counter reaches 29, say, before a zeroizing pulse arrives, and the other counters have not reached this state, a signal is sent to the appropriate one of four alarm relays al . . . a4 to indicate by means 21 ... 24 that a wheel is skidding and initiate corrective action. If all the counters reach 29 together an interconnecting arrangement 30 blocks operation of all the alarm relays al ... a4. A further four alarm relays bl . . . b4 are made receptive when the device 10 picks up a signal laid down by head 9 (only operative above a certain speed) and are subsequently blocked when the device 11 picks up the signal. During this interval if any of the counters reaches a count of 27, say, the corresponding alarm is operated.