Abstract: A nonintrusive diesel engine cylinder pressure transducer includes a congruously shaped fuel injector stud which has been internally instrumented with full-bridge electrical resistance strain gage circuitry. The instrumented fuel injector stud has a hole which has been bored axially lengthwise and a full Wheatstone bridge strain gage unit which has been situated in the hole. While the engine is running, the operative instrumented fuel injector stud, which has been replaced in its normal position in the fuel-injector/cylinder assembly, acts in combination with other assembly components as a cylinder pressure transducer. Measurements of tension and compression of the stud are provided which are reflective of pressure, mainly due to compression and combustion, in the engine cylinder. The full-bridge configuration eliminates bending effects and affords electrical temperature compensation. Practice of this invention advantageously avails existing structure.

Abstract: Apparatus for measuring thrust loading on a rotating shaft. A plurality of train gages, electrically connected in parallel and series to form one arm of a Wheatstone bridge circuit, are mounted at equal intervals on a thin strap or band formed to surround the shaft with a predetermined hoop load. Lubricating material disposed between the shaft and the band prevents transfer of friction forces from the shaft to the band. As the thrust loading increases, shaft dilation (girth increase) causes the band to stretch and increase its stress. This hoop stress is measured by the strain gages mounted on the band, and is transmitted as the output signal produced by the bridge via radio telemetry or slip rings to a remote indicator. A second arm of the Wheatstone bridge circuit, to provide compensation for temperature effects, can be provided by an additional strain gage mounted on a block of material identical to that of the shaft which block is in turn mounted on the above thin strap or band.