END-OF-LINE PRODUCTION TEST STAND EVALUATION OF TRANSMISSION NOISE

This paper is an attempt to define the requirements for an on-line transmission vibration detection system that could be incorporated on an existing final test stand. The purpose of the system is to assess transmission noise in order that production tracking of noise levels is possible. A series of experiments was conducted to define: the best sensor to detect noise levels, the optimum mounting location of the sensor, the ability of a system to discern implanted faults, and the correlation of the vibration levels from an in-plant measurement system to in-vehicle human ratings of transmission noise levels. Results of these tests showed: (1) an accelerometer mounted on the transmission housing offered the best signal clarity in terms of preselected criteria versus a microphone or monitor of fluid pressures, (2) in-plant test stand vibration readings did not correlate well with human ratings of noise when the same units were driven in vehicles, (3) the frequency spectrum plots showed a tendency for the defects to give spectra with higher amplitudes at the gear meshing frequency, (4) signal repeatability on the test stand is excellent, and (5) a technique known as Cepstrum analysis offers promise as a method to reduce the vibration data from the test stand to improve signal discrimination capability. A discussion of a possible production system is presented.