For existing fleets such as the U.S. military ground vehicle fleet, there are few ways to reduce vehicle fuel consumption that don’t involve expensive retrofitting. Replacing standard lubricants with those that can achieve higher vehicle efficiencies is one practical and inexpensive way to improve fleet fuel efficiency. In an effort to identify axle gear lubricants that can reduce the fuel consumption of its fleet, the U.S. Army is developing a stationary axle efficiency test stand and procedure. In order to develop this capability, on-track vehicle fuel consumption testing was completed using light, medium, and heavy tactical wheeled vehicles following a modified SAE J1321 type test procedure. Tested lubricants included a baseline SAE 80W-90, a fuel efficient SAE 75W-90, and a fuel efficient SAE 75W-140. Vehicle testing resulted in reductions in fuel consumption of up to 2%. Using data collected during vehicle testing and data from vehicle simulations, a stationary axle efficiency test stand was designed and built to allow evaluation of axle hardware under loading conditions representative of real world operation. The test stand was constructed in a modular fashion capable of fitting a variety of military axles, and test method developmental work was initiated using hardware representative of the light and medium tactical wheeled vehicles used during on-track vehicle testing. Results to date have shown the stationary test stand to have excellent ability to differentiate and map axle efficiency changes between lubricants. Stationary testing has also been shown to offer a higher degree of accuracy than full-scale vehicle testing (more tightly controlled conditions), and provides efficiency results at a much lower cost than full-scale vehicle testing. This work is intended to support the future development of a Federal Test Method (FTM) to define procedures to evaluate potentially fuel efficient gear oils (FEGO) for use in military ground equipment.
