Can a 10-speed transmission provide benefits over the traditional 18-speed? PowerTorque looks at the pros and cons
As a nation, Australians are what the marketing people call “early adopters”. We’ve got one of the highest numbers of mobile phones per head of capita, and the growth of email, Facebook and twitter has astounded just about anyone over the age of 25 years. Those under the age of 25 years just accept technological change at a rapid rate, on an almost daily basis.
The transport industry is quick to adopt in some areas, but can be slow in others, largely because of personal experience over what works and what doesn’t.
For many operators the choice for a gearbox starts and stops with an Eaton Roadranger 18-speed. All there is to decide is whether you want a manual version or one that does the ratio shifting automatically, as with the AutoShift or the more recent two-pedal UltraShift PLUS.
Admittedly, there are different versions that reflect power and torque capabilities under a wide range of weight variations, but that choice is often left to the sales personnel handling the deal. You say what you want and a suitable Eaton Roadranger fits the bill.
At least that was the situation. Over the past year, the North American market has been focused on providing better engine and transmission matching as part of the “SmartAdvantage” powertrain programme. This development sees a change from using the traditional choice of an 18-speed transmission and downsizing to that of a 10-speed, specifically for single-trailer application up to a GCM of 40 tonnes.
This programme has seen Cummins and also Navistar work together with Eaton to pair either the Cummins ISX15 or Cummins ISX12 engines with an Eaton 10-speed UltraShift PLUS AMT (Automated Manual Transmission).
Available for GCM applications of up to 50 tonnes with the ISX15, both the ISX15 and ISX12 come with what Cummins calls SmartTorque2 (ST2), which automatically senses vehicle weight, grade and operating gear, then selects the optimum torque for the best combination of fuel economy and performance in every gear.
The close-step ratio, combined with SmartTorque2, provides a balance of performance, delivering power when conditions demand it, such as steep road grades, heavy loads and cruise speeds of up to 100 km/h. These engines come with Vehicle Acceleration Management (VAM), a unique electronic feature that maintains a more consistent acceleration rate and more efficient transition through the gears, reducing driveline wear and adding fuel savings.
Features of the Eaton Fuller Advantage 10-Speed Automated Transmission include the strategic use of lightweight components and precision lubrication. Small-step technology enables down speeding in overdrive and efficiency in direct drive. Optimised shifting is based on grade, vehicle weight, engine torque and throttle position.
Fuel economy is further enhanced through Precision Lubrication, which reduces churning losses and eliminates the need for a cooler in applications up to 36,300 kg GCW. This reduces weight and increases reliability.
Having combined the Cummins ISX15 and ISX12 with SmartTorque2 (ST2) with the Eaton Fuller Advantage 10-speed Automated Transmission, both companies claim the result is three to six percent better fuel economy for the ISX15 and two to four percent better fuel economy for the ISX12. These gains come from the sharing of critical data between the engine and transmission, which determines the torque required to deliver the power level drivers need.
In these applications, Cummins runs the ISX15 at performance ratings of 309 and 336 kW (415-450 hp), with torque outputs of 1,450-1,750 lb-ft (1,966-2,373 Nm) at 1,000 rpm. For the ISX12 the figures are 276-317 kW (370-425 hp) and torque ratings of 1,150-1,650 lb-ft (1,559-2,237 Nm) at 1,100 rpm.
Navistar has taken its development a stage further. As well as offering the 10-speed Roadranger UltraShift PLUS in its ProStar and TranStar models, it has added the availability of the Allison TC10 matched to the MaxxForce 13 engine with SCR.
This new Allison transmission is the first fully automatic transmission for the Class 8 on-highway segment, providing a blended architecture with full-power shifts, a torque converter and a twin countershaft gearbox. The ten forward speeds and two reverse make the TC10 ideal for distribution applications where the work cycles for single-trailer application are split between city and highway conditions. Allison fleet testing has validated that drivers can achieve an average of five percent improved fuel economy.
Rated to accept up to 600 horsepower and 1,700 lb-ft of torque, the TC10 comes equipped with Allison’s newest generation of electronic controls, which provide superior fuel economy features, prognostics to eliminate unnecessary oil and filter changes, and enhanced shift selector functionality.
Although at first sight it might be easy to dismiss what happens in Navistar circles as being purely North American centric, there’s always the possibility that what occurs in the US may come to the Australian market through the CAT Trucks link.
The dramatic way in which a modern engine produces its power and torque ratings lower down the engine rpm scale could well be the trigger point for many fleets to consider downsizing in their transmissions. So too could a downsizing of engine capacity, with North America looking at the 13-litre alternative to traditional 15-litre Big Bore options.
The developments in the North American market have taken place alongside the shift to more stringent exhaust emissions levels, and the engine/transmission matching we have referred to has all been completed with this higher level of technology, basically at Euro 6 levels.
Graeme Weston, engineering manager at Eaton, told PowerTorque that currently the 10-speed UltraShift PLUS transmissions developed for the North American market were not at this stage available in Australia.
“It’s a very specific programme they run for their market. Because we are in a different exhaust emissions level scenario the lighter weight transmission has not yet been made available in the Australian market. There would need to be specific work completed on engine matching if we were to introduce these products here at our current emissions levels,” said Graeme.
As the introduction of Euro 6 appears to have almost stalled as far as a start date is concerned in our market, Australian operators might not have access to the improvements in fuel economy available from precise engine and transmission matching until as late as 2018.
Although, historically, most of the Australian transport industry has just about standardised on the 18-speed Eaton transmissions for on-highway work, there are operators that have downsized to 10-speed alternatives and gaining benefits in lower tare weight, lower purchase cost and improved fuel economy.
The exceptions to the rule here are companies like Dyers Gippsland Transport, which specialise in freight distribution, refrigerated transport and storage, predominantly between East Gippsland and Melbourne.
With its head office in Sale, and with depots at Morwell, Laverton, Bairnsdale, Dandenong and Adelaide, Dyers is a family-owned business that has operated now for four generations.
“We operate a fleet of approximately 110 vehicles and probably double that number of trailers, plus utes, forklifts and other equipment,” said Scott Dyer.
“We bought 18-speed transmissions only when we had big horsepower or when we wanted to take two trailers. These days, you really have to tailor your vehicles to your product and your market.
“It wasn’t such a big move to shift to 10-speed transmissions. It’s more than acceptable. It’s the so-called perception of the drivers. Peak torque is now developed over a wider range at lower engine revs. It’s changed the driving process.
“All our 10-speeds are Eaton UltraShift PLUS units behind Cummins ISX EGR engines and ISMe5s in Kenworth T-Series. A 10-speed is not an issue when it comes to resale.
“AMTs have two benefits. They are easier on the driver, but also easier on the driveline. It would be unusual for us to get over one million kilometres on a clutch, but it has happened on more than one occasion.
“It’s early days for the AMTs, and we are still working on the settings for them, especially to improve reverse creep when backing onto loading docks. We also operate DAFs with the ZF-AS Tronic AMT transmission, and 380 hp Scanias with the Opticruise AMT, and these are fine.
“Looking into the future, the PACCAR MX13-litre engine with the ZF transmission could also be of interest to us in the T409. We are also looking at universal adoption of Electronic Braking Systems for improve roll stability and safety, and this is a natural extension of having disc brakes on the European trucks,” said Scott.