Abstract: A cargo hook having fore and aft trunnions mounted in fore and aft bearings supported on frame members of a helicopter or the like, is provided with strain gauges secured in a bore in the aft trunnion for measuring shear strain on the trunnion by a load supported by the cargo hook. Additional strain gauges are secured in the aft trunnion bore for measuring axial and Poisson forces on the trunnion as the axis through the fore and aft trunnions varies from horizontal. The strain gauges are included in an electric circuit of a Wheatstone bridge and an indicator which converts the electric signals from the strain gauges to a readout of units of load weight. The strain gauges which measure axial and Poisson forces are connected in the electric circuit to compensate for the deviation from horizontal of the axis through the fore and aft trunnions, to provide an accurate readout of load weight applied to the cargo hook.

Abstract: The vehicle weighing system for a towed vehicle includes removable stub axles and a hitch rigidly connected to a load support. The hitch and one or more of the stub axles are gauged in an identical manner. Two active electrical strain gauges are placed in a hole formed in the supporting member to be gauged, such hole extending normal to the direction of the load. The hole is placed adjacent the end of the supporting member which is remote from the load support and the two gauges are oriented to reduce the moment sensitivity of the system to a minimum. The hitch is provided with additional compensating gauges which are not responsive to strain, and the axle and hitch gauges are connected to form a measuring bridge circuit. The gauging holes are sealed by end plugs, a printed circuit board, potting compound and a boot, all of which are flexible so as not to interfere with the weight measurement.