Control system for weighing of load in hydraulically operated lift assembly

Claim 1

In a loader of the kind having an hydraulically operated lift assembly including a load carrier, at least one arm associated therewith, a double-acting hydraulic cylinder operatively connected to said arm, a lift circuit and a lowering circuit for conveying hydraulic fluid under pressure respectively to a first end and to a second end of said double-acting hydraulic cylinder for respectively elevating and lowering said load carrier, and a control valve for switching the flow of hydraulic fluid under pressure between said lift and lowering circuits, and further including transducer means operatively connected to said lift circuit to provide a signal corresponding to the hydraulic pressure within said first end of said hydraulic cylinder, the improvement comprising: a low-resistance by-pass circuit comprising a return line tapping off from said second end of said hydraulic cylinder and normally-closed remote control valve means in said return line, operable to be open when said at least one arm is being elevated with the load carrier to a predetermined reference weighing position so that pressure build-up in said lowering circuit is avoided and the load weight reading corresponding to the hydraulic pressure in the lifting circuit is representative of the load in said carrier.