GB875508A - Means for indicating or utilising changes in tension of webs and the like - Google Patents

Abstract

875,508. Tension indicators. MARSH, J. C. Nov. 19, 1959 [Nov. 22, 1958; July 9, 1959], Nos. 37667/58 and 23560/59. Class 106 (2). [Also in Groups XVI, XXIV and XXX] In a device for indicating and/or utilizing changes in tension of a driving or conveyer belt 1, rope or chain, or of a moving or stationary web, such as textile or newsprint, or a thread in a sewing machine, wherein a jockey pulley 6 is transversely loaded on to the tensioned belt 1 and its transverse movement measures belt tension, the transverse load, spring 12 or gravity, is applied to the jockey 6 through a linkage, such as a toggle 4, 5, and bell-crank 10, which affords the load a continuously decreasing mechanical advantage as the jockey moves outwards towards the straightening position of the belt, thereby permitting increased movement of the jockey in the fully deflected high-tension region, where such movement would otherwise be too small to utilize. The response may thereby be made approximately linear with tension. In Fig. 1, the bell-crank 10 actuates, through an adjuster 18, a microswitch which disconnects the belt drive on overload; or the lever 10 may actuate a variable-speed gear to reduce the overload or maintain the belt load constant; or adjust the circuit of a driving electric motor. In long conveyer belts several such devices are installed at intervals along the belt to detect and correct unequal tension distribution. In a simple indicator, Fig. 2 (not shown), the toggle link 5 directly actuates a spring-loaded lever moving over a tension scale. In Fig. 3 (not shown), the toggle levers are replaced by an equivalent bowed leaf-spring, longitudinally spring-loaded. In Fig. 4 (not shown), the jockey is guided transversely and is connected to a single spring-loaded link slidable at its opposite ends in slots at right-angles in a guide plate.