Patent GB-868800-A (GB)
Title: Improvements relating to equipment for detecting moving vehicles according to their speed
Inventor: COUPER JONATHAN EVERY
IPC: B61L17/00
Filed: 1957-05-01
Abstract: 868,800. Indicating speed of vehicles. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. April 18, 1958 [May 1, 1957], No. 13887/57. Class 105. The detection of vehicles passing through a section of track takes place in dependence upon the speed of the vehicle, e.g. if the speed is below a certain value, this being effected by an entry contact setting into operation a timing device which is re-set to its starting state when an exit contact is actuated and only if the timing device has been in operation a sufficient time is a signal given which thus denotes the presence of a slow-moving vehicle in the section. The arrangement is applicable to denote the presence of one or more slowmoving vehicles in a track section of a marshalling yard. There may also be means to give a " track full " signal when a predetermined number of vehicles are in the section. The timing device is preferably a condenserresistance charge and discharge arrangement controlled by stepping switches actuated by entrance and exit contacts of the track length. In the arrangement shown a vehicle entering the track length T (at the left-hand end) moves past a track device D A  to actuate through its contact d A  the stepping magnet E A  of a stepping switch S A  having two banks of contacts B A <SP>1</SP> B A <SP>2</SP>. Alike track device D B  and stepping switch S B  at the exit end of the track length T are actuated by a vehicle leaving the track length. With the track length unoccupied the contact arms of the two stepping switches are resting on corresponding contacts, i.e. contacts numbered 2 on the banks B A <SP>1</SP>, B B <SP>1</SP> in the particular position shown. The condenser C is in effect therefore short-circuited, the resistance R D  being only such as to avoid sparking at the contacts. On entry of a vehicle the wiper arm C A <SP>1</SP> of stepping switch S A  moves on to contact 3 of bank B A <SP>1</SP> to remove the shortcircuit whereupon the condenser begins to be charged up through a resistance Rc from a tapping on a resistance line R2, R1 supplied by a source HT+. The growing. condenser voltage is applied to the grid of a valve V1 of an electronic triggering arrangement VR and after a due time a relay IR in the anode circuit of a valve V2 of the triggering arrangement is energized to signal the presence of a slowmoving vehicle in the track length. The condenser is discharged when the vehicle, leaving the track length, actuates the exit device contact d B  to bring the contact arm C B <SP>1</SP> of the stepping switch S B  on to contact numbered 3 of bank B B <SP>1</SP> and so in line with contact arm CA<SP>1</SP> to effect the short-circuiting of the condenser. If a following vehicle should enter the track length before a first one has left, then the stepping switch S A  will be stepped further ahead and by appropriately connecting the second contact banks B A 2, B B <SP>2</SP> of the two stepping switches S A , S B  the presence of a predetermined number of vehicles in the track length will be signalled, e.g. by the picking up of a stick relay HR. As shown, contact numbered 1<SP>1</SP> of bank B B <SP>2</SP> is connected to contact numbered 4<SP>1</SP> of tank B A <SP>2</SP> and the other similarly with the result that the relay HR will be picked up when there are three vehicles in the track length and give a " full " signal for the track length. This signal is only cancelled when a push-button PB is depressed to break the stick circuit. The track devices D A , D B  may be treadles or photo-electric or magnetic detectors controlling the entry and exit contacts d A , d B .