Toledo, OH--Many transmissions used on heavy trucks rely upon splash lubrication. Gears spinning in an oil bath distribute lubricant inside the transmission. Slinging oil about in this manner generates heat. Further, distribution of lubricant by a splash system is a bit random, so some gears and bearings don't receive proper lubrication. Excessive heat buildup and accelerated transmission wear can result. High ambient temperatures, such as a trucker might encounter in southern Nevada in August, aggravate this situation.
Conventional transmission lubrica-tion/cooling systems consist of an external or internal pump that circulates lubricant out of the transmission to an external oil cooler, and then back to the transmission's sump. Mike Essi, chief engineer, advanced products, and his colleagues at Dana Corp.'s Spicer Transmission Div., found a more elegant solution. They designed a small lubricant distribution system into all Spicer's nine and ten-speed transmissions.
Standard equipment from Spicer as of this summer, the Optilube system consists of a compact, gear-driven, off-the-shelf gerotor pump to move lubricant and tubing to conduct it. Approximately 2.5 inches in OD and 0.75 inch thick, the pump displaces 1.18 cu-inches/revolution. It can pump about 8 gal/minute at 2,100 rpm.
Under a pressure of 3 to 5 psi, oil moves to components through tubing that's about ½ inch in diameter (tubing size and shape vary somewhat). There are a series of holes over critical points, and oil is sprayed onto each of them. Hole location directs the streams of oil at their targets. The system works in all gears, including neutral and reverse.
In addition to placing lubricant exactly where a transmission needs it, engineers also reduced the volume of oil in Spicer transmissions from 27 pints to 18 pints. Doing so elevates the spinning gears above the level of the oil. Thus the gears cannot churn it up and produce heat.
Cooler operation and continuous lubrication of critical transmission components results in: longer oil life; longer gear and bearing life; less friction; higher transmission efficiency; and, according to Spicer, improved fuel economy. If a user needs an external oil cooler for some other reason, the Optilube pump can move oil in and out of the transmission via a set of ports, to the cooler.
Additional details...Michael Penland, Spicer Transmission Div., Dana Corp., Box 986, Toledo, OH 43697, (419) 470-8344.