For decades, European truck manufacturers have been faced with a choice of using ZF transmissions or developing their own gearboxes for heavy trucks. But now Eaton, one-time maker of the legendary Twin-Splitter, has launched itself back into Europe’s heavy truck market.
At the IAA last month, it showed its Endurant 12-speed automated manual transmission, developed in conjunction with Cummins.
Designed from the ground up as an automated transmission, the layout of the gearbox precludes the use of a stick-shift – all shifting is on linear rails. The electronics and pneumatics which handle shifting are all integrated into the structure to reduce clutter around the transmission. However, the linear clutch actuator and electronic control module are both easily accessible on the top of the main casing.
It requires only 7.5 litres of oil and that only needs changing at 100,000 km, despite there being no external oil cooler. The gears do not run in oil, but are sprayed with lubricant. Durability is not compromised: Eaton says that Endurant enjoys a five-year warranty in the USA, with the clutch being covered for four years.
Maximum allowable torque is 2,508 Nm, allowing operation at weights of up to 55 tonnes. The transmission has twin countershafts and helical gears: ratios are in 2 x 3 x 2 configuration. Eaton claims it has the widest ratio spread on the market, and is ideal for modern ‘downspeeded’ engines.
Its 430 mm clutch is self-adjusting and features a prognostics facility which provides notification before service wear limits are reached. The input shaft has a replaceable sleeve, which can be changed when worn without disturbing the rest of the unit. There is an oil-pressure sensor and the transmission has a limp-home mode. The electronic controls are compatible with modern GPS enabled terrain-aware engine management systems.
All Endurant transmissions have an eight-bolt cover over the PTO port, allowing a vehicle to be retro-fitted with a PTO for second-life applications.
Endurant has been in operation with customers in North America since last year. Although developed in conjunction with Cummins and fitted mainly to Navistar, Kenworth and Peterbilt brand trucks behind Cummins and Paccar engines, an Eaton spokesman told Transport Operator that even some Volvo customers were choosing it in preference to the manufacturer’s own transmission in the USA.
The self-contained design of Endurant makes fitting it to different makes of trucks a fairly simple operation: it just needs the air and electrical supply plumbing in. Eaton claims that on a like-for-like basis, Endurant is 47 kg lighter than the rival ZF TraXon currently used by DAF and MAN in Europe, and says that Scania and MAN parent company Traton is expressing interest in it for the European market.
Meanwhile, American transmission specialist Allison is seeking to widen the appeal of its automatic gearboxes beyond its traditional European markets of buses, municipals and fire appliances.
It showed a new nine-speed ‘box at the IAA, aimed not just at city-bus but also distribution applications at gross weights of up to nine tonnes developed from the existing six-speed 2000 Series transmission, but with three overdrive gears.
Ashley Brown, the area director for UK and Ireland, said the success of the Allison transmisions in Dennis Eagle and Mercedes Econic vehicles in non-municipal applications in London had led Allison to look to expand into other sectors. The combination of relatively narrow ratio bands with the deep reduction axles found on municipal chassis meant many operators were finding the limitations of these vehicles outside of the intensive urban part of their operating cycle.
Allison was working with Dennis Eagle in particular, to identify an optimum axle ratio for mixed applications – changing from 6.82:1 to 4.5:1 to cover a mix of urban and rural work.
New software would also help keep the engine in its sweet-spot over a wider range of road conditions. It would hold a gear longer if necessitated by load or incline.
“This could make automatic transmissions suitable for distribution or long-haul work…it could increase take-up beyond refuse collection,” he said, adding that they were also very suitable for on/off-highway applications.
The nine-speed development of the 2000 will save around 100 kg over the 3000 Series.
Allison is also developing new integrated hybrid transmissions which fit into roughly the same envelope as the 3000 Series. They give an extended zero-emissions range of up to 15 km, and are supplied as a drop-in fit with battery, inverter and other equipment.