Trucks were some of the first vehicles to adopt automated manual transmission systems in the 1980s, and Eaton was among the first transmission suppliers to launch such a system with its Semi Automated Manual Transmission. Cost and additional complexity have been likely factors in lower levels of interest in a dual clutch automated system, but Eaton has now released details of its Procision dual clutch transmission, unveiled this fall at the IAA Hanover truck show, aimed at middleweight trucks and buses up to 16-t gross vehicle weight.
The transmission features seven speeds and uses an all-aluminum casing. It is electronically controlled and hydraulically activated. Following established dual-clutch practice, the system changes gear by switching between clutches to engage a pre-selected gear. Synchronizer rings are used to aid gearshifting.
According to Tony Truelove, Global Truck Marketing Communications Manager at Eaton, the transmission is a direct competitor to the torque converter automatic Allison 2000 series.
“The largest primary advantage is fuel economy,” said Truelove. “Up to 8 to 10% improvement over the latest-generation torque converter automatic. The transmission has adjustable forward and reverse creep mode, enabling a much slower pace than an equivalent torque converter automatic. We also have a feature that we call Hill Helper, which holds the dual-clutch mechanism on gradients up to 8% at 26,000 lb (11,800 kg) for up to three seconds.”
The Procision transmission uses a wet clutch system and the transmission needs one type of oil for the entire unit. An oil cooling system is used to help extend operating life. The dual clutch module is completely contained within the transmission casing. Torsional vibrations are controlled using a five-spring damper. This is sealed with the aim of eliminating contamination. New synthetic oil enables oil and filter change intervals of 150,000 mi (240,000 km). Eaton says that the internal sump filter and electrical system do not require maintenance.
The transmission control module is mounted on the transmission casing and all wiring is contained within the casing, helping to ensure that wiring is not vulnerable to external damage.
Transmission features include Eaton Dynamic Shifting, a software mode that permits the transmission to shift automatically between “economy” and “performance” gear change schedules, according to weight, gradient, and demand from the driver. Eaton claims that economy and performance shift modes can be adjusted to customer requirements.
Procision also features brake pedal-actuated Tap Down Shifting, which enables downshifting on gradients or in other circumstances without the driver removing his or her hands from the steering wheel. Similarly, when the transmission is in Low mode, Automatic Grade Braking is actuated to reduce speed on long steep gradients, by automatically downshifting.
The transmission offers a choice of three power takeoff points and these can be activated altogether or individually from the factory, by a dealership or by subsequent owner if not previously activated.
Initial production will be aimed at North America, but Procision will be produced for other markets when there is demand. The transmission will be available in North America from July 2015.