The safety factor of hydraulic piston pumps and motors shows a tendency to decrease due to high pressurization, high speed and low weight/volume realization to enhance the output density. Therefore, more effective test models are necessary to predict the exact life. The sensitive parameters in the endurance life test are speed, pressure and temperature, and failure production increases in proportion to the operating time. In this research, the authors propose a combined accelerated life test model using the analysis method of the combined accelerated life test results of piston-shoe assemblies by simultaneously applying high speed, high pressure and high temperature in accordance with the variation in speed, pressure and temperature in order to reduce the life test time.

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In this study, we proposed a process of an accelerated life testing method of 5-speed manual transmissions used in vehicles, which loads are consisted of multiple alternating loads. The entire process of an 5-speed manual transmission’s accelerated life testing method where no failures are allowed, is a process that requires an abundance of assumptions, and other factors that are estimates such as the shape parameter, beta() and the fatigue damage exponent (x). And the process is consisted of 7-step process. From the 1-setp, which is the deriving the service(use) torque and speed(rpm) profile of the transmission, to the 7-step, we could determine the accelerated life time, the accelerated torque and the accelerated speed(rpm), which are the equivalent cumulative fatigue damage. Also, we have performed accelerated life test on 5-speed manual transmission by using the following 7-step process.

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