Patent GB-1487152-A (GB)
Title: Apparatus and method for weighing railroad cars coupled together and in motion
IPC: G01G19/04
Filed: 1975-07-21
Abstract: 1487152 Weighing railway wagons electrically RAILWEIGHT Inc 21 July 1975 [31 July 1974] 30408/75 Heading G1N Apparatus for weighing railway wagons of various lengths whilst in motion and coupled together, comprises a weigh bridge which supplies the current weight of axles on it to a current weight register each time a new axle enters the bridge; processor means including a previous weight register and adapted to subtract the previous weight from the current weight to derive the weight of the new axle, and a memory in which the axle weights are stored. When the last axle of a wagon has been weighed, the weights of all its axles may be recovered from the memory and added together to give the total weight; alternatively if all the axles of the wagon are on the bridge, the weight of any axles belonging to another wagon on the bridge may be subtracted from the current weight to give the full draft weight. Trackside apparatus, Fig. la, comprises the axle-operated switches SW1-SW5 and their associated relays. SW3 and SW5 indicate respectively when an axle enters and leaves the weigh bridge section WR; SW2 and SW4 are arranged to advance of SW3 and SW5 by not more than half the minimum spacing between two axles and give advance warning that an axle is about to enter or leave the bridge. SW1 is provided to detect a locomotive on the basis of axle spacing and inhibit print-out when a locomotive is on the bridge. Further means provide a "last axle" signal and may comprise photo-electric means for detecting the end of a wagon. Switches SW2 and SW3 may be used to operate warnings that the wagons are moving nearly at or above the maximum acceptable speed by comparing the interval between their operation with the periods of two monostable circuits, Fig. 14 (not shown). Weighing apparatus, Fig. 1a, comprises a bridge of strain gauges WSA coupled to a low pass filter F which cuts off at about 10Hz and supplies an amplifier VA coupled to a voltage to frequency converter VFC the output of which feeds a counter 52 for a fixed period timed by a digital clock 43. The start of the fixed period is initiated by a signal on the "START WEIGH" line from the computer apparatus. Computer apparatus, Fig. 2. Signals from the track pass to unit 300 which selects an appropriate routine according to whether an axle is entering  or leaving the bridge, whether an axle is entering whilst another is about to leave, and whether a last axle signal is present. The routines are designed so that when an axle enters, the previous bridge weight is subtracted from the current one to derive the axle weight which is stored in the axle library 1001; if an axle is about to leave, this process is delayed until the weight of the axle about to leave has been subtracted from the previous bridge weight. These processes are  affected by the routines, the sub-routines selected in unit 500, and the sequences provided by the controller 800 which control the processor or 701. The unit 600 counts the number of axles on the bridge and the number of axles in each wagon (counters 615 and 614, not shown) and on receipt of the last axle signal determines which count is larger. If the former, the weights of axles which do not belong to the current wagon are retrieved from the axle library 1001 and fed in turn to the processor 701 with instructions to subtract them from the current bridge weight. The sum then remaining is the full draft weight and is printed out. If the whole wagon is not on the bridge its individual axle weights are retrieved and fed to the processor 701 which adds them up and produces an axle sum which is printed out.