Abstract: An extent of travel detection system particularly adapted for measuring piston bottom excursion in an internal combustion engine. Two eddy-current position transducer probes are provided for each piston, the first being positioned to sense piston bottom travel position and the second being operated as a reference probe, mounted in close proximity to the first probe. The first probe of each pair is only operated to measure piston travel within the cylinder during the brief moment that the piston is near its bottom. The actual point of the bottom travel is detected, using the reference probe to compensate for environment effects such as temperature. The measured bottom point for each piston is displayed either by a separate or shared display. Changes in the displays over time indicate engine wear or impending failure. The measured bottom points are typically averaged over a selected number of engine cycles.

Abstract: A remote reading crankshaft alignment tool utilizes a differential transformer and live centers to measure the deflection of crankshaft webs as a function of crankshaft angle. The tool is positioned between adjacent webs to measure the difference in spacing between preset points on the crankshaft webs as the crankshaft is rotated, with any misalignment resulting in a difference in output as the crankshaft is rotated. The live centers are in the form of conical-shaped feelers mounted in bearings, with the live centers fitting into punch marks in opposing webs. In one embodiment, one feeler is fixed with respect to the tool body and the other is spring-loaded and slidably mounted in the tool body. An extension of the slidably mounted feeler includes a ferromagnetic coupling slug which is initially centered in a split-winding differential transformer within the tool.

Abstract: A system for monitoring misalignment between two in-line rotating shafts and for indicating the direction of shaft misalignment wherein alignment sensors are mounted directly to and rotate with the shafts. The sensors are mounted to detect position or stress variations between elements on coupled shafts as a function of the rotational position of the shaft and thus errors normally encountered where the sensor is positioned off the shaft are avoided. A coupling system such as a rotary transformer is employed to apply power to the sensors and associated circuitry on the shaft and to receive from the shaft signals indicative of sensed misalignment. A signal representative of relative phasing between the rotating shaft and surrounding equipment is provided and is used in electronically processing the misalignment signals to provide output signals indicative of the direction and orientation of misalignment between the rotating shafts on orthogonal axes.