Abstract: A torque wrench having a torque plug integral with the back side of the torque wrench handle and with strain sensing elements mounted on the torque plug and connected to signal processing circuits supported by the handle which control a digital display unit mounted on the handle. The processing circuits include a peak hold detector enabling display of the peak torque value during a torquing operation, and a peak hold response delay insuring capture of the peak torque value.

Abstract: The adapter includes a luminosity probe for replacing the glow plug associated with the selected cylinder in a diesel engine, a timer circuit responsive to inception of each electrical signal generated by the luminosity probe to produce a timer signal. The timer signal is differentiated to produce a spike. A pickup loop receives the spike and produces an inductive signal for application to the clip of a spark-ignited-engine timing meter.

Abstract: An oscillator provides a series of pulses to the first of a plurality of cascaded counters. The BCD outputs of each counter provide a particular digit in the number of pulses counted during selected intervals. At least two AND means are coupled to respective sets of the counter outputs to provide speed signals when the corresponding numbers of pulses have been counted. A selected one of such signals resets the counters and also provides an inductive output for the magnetic probe of a timing meter. Additional AND means are respectively coupled to different sets of the counter outputs and provide timing signals when their respective numbers of pulses have been counted. A selected one of the timing signals energizes an LED which produces a light flash for the luminosity probe of the timing meter.

Abstract: The probe includes a tubular housing having a first portion and a second portion. The first portion is adapted to be mounted in place of the glow plug of a selected engine cylinder. A light pipe within the first portion directs light from the combustion zone to a phototransistor within the second portion. The front of the first portion has a reduced size aperture defined by an internal shoulder against which the front of the light pipe is seated. The rear of the first portion carries resilient sealing means which is deformed when the second portion is telescoped thereon so as to provide a detachable, frictional, light-tight thermally insulated connection therebetween. A phototransistor is mounted within the second portion to convert light passing through the light pipe into electrical signals. A cable carries these electrical signals to processing equipment. A base resistor is located in the second portion between the base of the phototransistor and the cable.

Abstract: A first signal at a first frequency which is a selected harmonic of the resonant frequency of a bolt in a first loaded condition is determined. Then there is determined a second signal at a second frequency being the same harmonic of the resonant frequency of the bolt in a second loaded condition. Both frequencies are multiplied by a factor M. The up input of a counter receives one of the signals for a predetermined duration, and the down input receives the other signal for the same duration. The number of pulses remaining in the counter is representative of the difference in load between the first and second loaded conditions.

Abstract: The apparatus comprises a luminosity probe to provide an electrical signal in response to the combustion event in a diesel engine and also comprises a probe to provide another electrical signal indicative of top dead center. Both electrical signals are processed and applied to a circuit which generates an output pulse having a duration corresponding to the time between the start of the electrical signals. A meter displays the angle represented by the duration of such pulse. Circuitry is provided to compensate for offset.