Overload detecting system

914,572. Fork lift trucks. YALE & TOWNE MANUFACTURING CO. Oct. 14, 1960 [March 22, 1960], No. 35235/60. Class 78 (3). An overload detecting system for a fork lift truck, in which the mast assembly 12 is pivotable on a shaft 19 under the action of an hydraulic ram 21, comprises a spring 24 interposed between the piston-rod 23 and a bracket 31 on the mast assembly, control means being provided to actuate a warning device or to stop lifting of the load when a predetermined moment is applied to the truck by a load producing a predetermined deflection of the spring. As the movement produced by the load on the truck increases, the arms 24a, 24b, Fig. 2, move apart thereby allowing a bell-crank 34, which is pivoted to the arm 24a at 37 and which is provided with a roller 40 engaging the arm 24b, to turn about its pivot 37 in a counterclockwise direction under the action of a spring 43 so that, when the movement reaches a predetermined value an adjustable screw 41 on the bell-crank engages a push-button 44 on a switch 33 to actuate a warning device, stop lifting of the load carriage or stop operation of the truck if the overload is not relieved within a short period determined by a time delay device. The spring 24 is pre-stressed by a bolt 45 so that it is not stressed under normal working conditions, and bolts 47 prevent overstressing of the spring. Specification 832,442 is referred to.