Eaton: SAE tests prove fuel efficiency of UltraShift HV

Eaton Corp. said that recent tests show its UltraShift HV medium duty automated transmission in a Class 7 truck is far more efficient than a fully automatic unit of an unnamed competitor.

Eaton’s Bill Gross, product manager of medium duty transmissions, said the results of SAE/TMC J1526 Type III fuel consumption tests showed that savings amounted to 19 percent, or $1,490 per year, in the urban route when fuel costs $2.85 per gallon. The unit also saves 7.5 percent in a highway version of the same test.

Eaton officials announced the results in a teleconference with trucking journalists this week. Contacted later, Nick Richards, spokesman for the Allison Transmission Division of General Motors Corp., said that a transmission’s overall productivity depends on exactly how the truck is used.

He said that the fully automatic Allisons often are more productive than automated transmissions. The company has found that there are applications where an operator loses some trips per day because the automated transmission accelerates much more slowly at low speeds than an automatic.

Gross said that in some of Eaton’s simulations, time savings with the conventional automatic amounted to a negligible one second per day.

Eaton experts attributed the UltraShift HV’s fuel savings primarily to the early lockup – full engagement of the clutch – in the transmission, which uses a conventional clutch. Fully automatic transmissions use a hydraulic torque converter, which the Eaton experts say does not lock up until 24 mph. While the drive is carried through the unlocked torque converter, there are energy losses somewhat analogous to a slipping clutch. The UltraShift HV’s standard clutch locks up at 3 mph.

Further savings stem from the factory fill of fully synthetic Roadranger lubricant, which is good for 500,000 miles, the life expectancy of the typical Class 7 truck in which it will be used, Eaton said. Gross stated that the competitive fully automatic transmission requires filter changes at 5,000 miles and then every 50,000, as well as 100,000-mile fluid changes. This is estimated to cost $210 per year. Thus, in pickup and delivery service, Eaton claims a savings of $1,700 per year with the UltraShift HV.

The UltraShift HV also eliminates the need for a transmission cooler, something required on a conventional automatic. New truck cost is about the same with the UltraShift HV as with a conventional automatic, Eaton said.

Richards also noted that many Allison customers use their trucks in difficult environments in which clutch wear would be a serious problem. “They find that, over the life of the vehicle, fluid changes are much cheaper than clutches,” he said.