Patent GB-924205-A (GB)
Title: An installation by which is obtained a measurement which represents the acceleration of a railway vehicle
IPC: G01P15/16
Filed: 1961-03-13
Abstract: 924,205. Computing speeds. SIEMENS & HALSKE A.G. March 13, 1961 [March 11, 1960], No. 9185/61. Class 106 (1). [Also in Group XXX] Apparatus for obtaining a measurement representing the acceleration of a rail vehicle descending a gradient incorporating a measuring track section L and for use in determining the rolling resistance of the vehicle in a hump yard system, comprises partial track sections S 1 , S 2  at the entry and exit of the measuring section L defined by rail contacts K 1 , K 2  and K 3 , K 4  respectively, means controlled by the rail contacts, for counting a number of pulses, which are generated at a pulse repetition rate which decreases with time, during the period the vehicle is in each partial section, said counts being proportional to the square of the vehicle speed in each section and means for obtaining the difference between the counts in the two partial sections. Since the acceleration where V 1  and V 2  are the mean vehicle speeds in sections S 1  and S 2  respectively and L is the distance between the sections, the difference count obtained represents the acceleration of the vehicle. Fig. 2 shows the relationship between the square of the mean speed V of a vehicle in one of the sections and time, from which it can be seen that if the time is measured by pulses generated at a chosen decreasing rate the incremental change in the square of the mean speed (V<SP>2</SP>) is constant between pulses. The pulse generator simulates this condition by reducing its repetition rate in stages-each stage consisting of say 5 cycles at a constant repetition rate. When a vehicle enters section S1 and operates contact K 1 , unit K, Fig. 3, emits a pulse to a timing device ZG which releases counter Z 1  and starts a repetition rate selector TW which controls a frequency divider FT. This is supplied with pulses at a fundamental rate, e.g. 3.2 kc/s. from a crystal oscillator G and shaper J and initially supplies one counting pulse to counter Z 1 , after each fourth fundamental pulse. When the counter reaches a count corresponding to time t o  (the time required for a vehicle to pass through either partial section at a maximum speed) it applies a pulse via line 40 to the repetition rate selector TW which adjusts the divider so that one counting pulse is produced after each fifth fundamental pulse. At further particular counts corresponding to ta, tb, tc &c., the pulse repetition rate is further reduced. When rail contact K 2  is actuated the repetition rate selector is brought to its initial position, the divider is reset and blocked and counter Z 1  retains its count. During the passage of the vehicle through section S 2  a similar action is performed with counter Z 2  receiving the counting pulses. When contact K 4  is actuated a difference counter DZ is released and pulses at the highest repetition frequency are applied to line 30. These pulses step counters DZ and Z 2  forward until the count in Z 2  equals that in Z 1  as determined by a coincidence circuit M. This circuit produces an output pulse which blocks the timing circuit ZG and hence the counters DZ and Z 2 , the repetition rate selector and the divider stage. The count in DZ equals the difference in the counts in Z 1  and Z 2  and this is supplied via line A to a computer which determines the rolling resistance. A return pulse from the computer, when the signal is registered, returns the apparatus to normal.