PRACTICAL APPLICATION OF MEASURED ACTUAL TORQUE TO SERVICE STRENGTH EVALUATION OF DRIVELINE

Recently, the reduction of the gear ratio of the driveline (hereinafter called "high gearing") has become popular as a means of improving the fuel consumption of passenger vehicles. Generally, an overtop on the manual transmission and the adjustment of the gear ratio of the final gear are means adopted for this purpose. According to the running performance diagram of the engine, if the gear ratio of the driveline is reduced in this manner, input torque to the manual transmission can be expected to be increased during cruising, and this could be hard on the gears and bearings. When driving in the field, however, it is not easy to estimate the frequency of the actual torque because such driving includes various driving conditions besides cruising. Moreover, the severity of the operation environment must be evaluated not only with actual input torque but also the actual operation frequency of each gear shift position. Accordingly, the measurement of actual torque under various driving conditions is indispensable in examining the strength and durability of the driveline. This report describes methods of measuring and analyzing actual torque and presents a method of determining the criteria for test driveline durability of the manual transmission.