GB859049A - Road vehicle detector - Google Patents

Abstract

859,049. Road traffic detectors. EASTERN INDUSTRIES Inc. March 4, 1957 [March 5, 1956], No. 7145/57. Class 118 (2). A multi-contact road pad comprises an elongated base 5 extending across the traffic lane perpendicular to it, and a number of elongated contacts 3, 4 supported on the base in side-by-side relation and arranged at a slight angle (e.g. 1 inch in 8 feet) with respect to the longitudinal axis of the base to provide overlapping actuation of the successive switch contacts by a pair of transversely spaced wheels 8, 9 of an axle. The unit is covered by a watertight resilient casing 1. For a vehicle moving in the direction shown in Fig. 3, contact 3 closes to energize relay IF which in turn energizes relay 2F. As the vehicle moves on, contact 4 closes energizing relay IR which provides a hold circuit for relay 2F. Further movement opens contact 3 releasing relay IF, relay 2F remaining energized over the contacts of relay 1R. Relay 3F is energized over contacts 2F2 and 1F3 and completes a self-holding circuit over contact 3F1. When the vehicle moves clear of the pad, relays 1R, 2F release and a " forward counter " FC operates, this releases relay 3F, and the equipment restores to normal. Passage of a vehicle in the reverse direction operates a " reverse counter " RC, by a similar sequence of events.