Axle Efficiency Comparison Method and Spin Loss Benefit of Front Axle Disconnect Systems

There are a variety of test protocols associated with vehicle fuel economy and emissions testing. As a result, a number of test protocols currently exist to measure axle efficiency and spin loss. The intent of this technical paper is to describe a methodology that uses a singular axle efficiency and spin loss procedure. The data can then be used to predict the effects on vehicle FE and GHG for a specific class of vehicles via simulation. An accelerated break-in method using a comparable energy approach has been developed, and can be used to meet the break-in requirements of different vehicle emission test protocols. A “float to equilibrium” sump temperature approach has been used to produce instantaneous efficiency data, which can be used to more accurately predict vehicle FE and GHG, inclusive of Cold CO₂. The “Float to Equilibrium” approach and “Fixed Sump Temperature” approach has been compared and discussed. Independent Front Suspension (IFS) axles were used for this project as an enabler to determine the spin loss benefits of Front Axle Disconnect (FAD) systems. The test protocol has been validated with axles of different sizes and designs.