Utilizing An Energy-In-Energy-Out Approach to Simplify Heavy-Duty Transmission Efficiency Testing

SAE Recommended Practice J1540 provides an indirect method of measuring transmission efficiency. The method involves measuring torque losses resulting from a dynamometer setup in which two test transmissions are mounted in a fashion that allows them to rotate about their input and output shafts. For a variety of reasons, an energy-in-energy-out measurement approach may be more practical for heavy-duty vehicle transmissions. With an appropriate test setup, the analysis simplifies to comparing the torque entering the transmission to the torque leaving it, factoring in the gear ratio.