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Transmission shift lever jumpout is a truck system dynamics problem that is caused by engine/transmission pitching in response to rough road input. Severe rotational motion imposes inertial forces on the shift lever system, potentially causing the shift rail to move to neutral. Dynamic testing and analysis has led to suggestions for system design improvement including lever geometry optimization and engine mount stiffness and damping improvement. A counterweight addition to the lever system will also stabilize the dynamics.

A PC based instrument called the Driveline Vibration Analyzer (DVA) has been developed and successfully proven as a field diagnostics tool to analyze driveline torsional vibration for the trucking industry. The DVA measures cyclic speed variations at any point in the driveline, and plots the corresponding torsional vibration amplitude versus rotational order. It readily measures the driveline response to engine and universal joint torsional excitations. Field application of the DVA has repeatedly demonstrated that damaging driveline torsionals can be controlled through the application of soft damped clutches and the maintenance of recommended universal joint working angles.

A gear tester has been developed that can predict the relative level of axle noise in the cab of a truck. This paper documents the development in five parts: establishing the characteristics of noise generated by the axle in the cab of a small gas powered truck, developing a viable gear tester for the noise quality measurement of spiral bevel gear sets, establishing correlation between gear tester ratings and in-truck ratings of axle noise, testing a random sample of gears to determine the population's noise quality distribution, and predicting the errors associated with using the gear tester in quality control.