Measurement of lubricating film thickness, temperature and pressure in gear contacts with surface topography as a parameter

Thin film transducers, sputtered onto a tooth flank, are used to measure temperature, pressure and oil film thickness profiles in gear contact. The former two are resistance sensors, while the film thickness sensor functions as a capacitive transducer. Experiments were carried out with ground and hobbed gears. The measurements are repeated after the tooth flank has been polished. The differences of the measured values for the ‘rough’ and ‘smooth’ surfaces are used for comparisons between differently machined surfaces. An EHD simulation programme has been developed which calculates film thickness and contact pressure, also taking surface roughness into account.