Mike Fowler, Cummins’ On-Highway Engine Director, is the man charged with overseeing the Cummins Integrated Powertrain program to ensure optimum results are achieved for Cummins’ customers. His prowess as a multi-combination driver means he is often behind the wheel of test trucks wired with fuel consumption meters and other testing paraphernalia while running up and down the highways.
Along with the Hume Highway that links Sydney with Melbourne, the Pacific is amongst the busiest freight routes in Australia with thousands of trucks treading its tarmac on a daily basis.
The stretch between Coffs and Newcastle is particularly tough going for trucks with a plethora of peaks and troughs of varying degrees. What better route to conduct testing on Cummins’ latest and greatest engines?
The engines are fitted in Kenworth K200 Aerodyne prime movers operated by, express freight specialist, AJM Transport based at Beresfield near Newcastle. This company also owns the curtain-sided B-double set loaded with concrete blocks providing a gross combination mass of 62 tonnes. As you would expect, AJM Transport is a strong supporter of the red engine company and currently owns 46 Cummins-powered Kennys.
Mike has driven the Euro-5 example from Newcastle to Coffs so it’s my turn to pilot it back to the coal city. Turning the key brings the X15, boasting 550hp and 2050ftlb (2779Nm) of torque, quickly to life and it settles into a smooth idle before D is selected and we are underway.
This unit is fitted with tall 3.73 diffs and once at full highway clip the tacho needle hovers just above 1,400rpm, well below the magic 1,550 mark above which peak torque starts to taper off. To me, the final drive gearing seems spot-on for this weight and route as the computer allows the engine to lug back to 1,200rpm on the steeper climbs before dropping two gears simultaneously, which raises the revs to 1,600, at which point it really digs deep and hunkers into the pull like a locomotive.
This is a point that Mike is keen to elaborate on, explaining that Cummins has been using six K200s for testing purposes, including the two featured in this report, over the past few years.
“When these trucks were new, before the Integrated Powertrain Calibration (IPC) was introduced, they had the standard ADEPT calibration of 600hp/ 2050lbft while they now have the IPC which is 550hp/ 2050ftlb,” he says.
“Apart from the horsepower, the main differences between the two calibrations are that while they produce the same 2050lbft, with the IPC it comes in at 1,000rpm compared to 1,200rpm with the standard calibration. At the other end of the scale the IPC limits maximum engine speed under power to 1,800rpm whereas the standard version is limited to 2,000rpm.
“With the earlier down-sped ADEPT calibration the trucks were geared really tall and getting great fuel figures on flat running and the drivers were able to change gears manually and still getting 600hp at 1,800rpm on the hills.
“So after switching over to the IPC the guys doing lighter B-double work at around 50 tonnes are getting terrific fuel economy and don’t have any issues on the hills but the ones running at 62.5 tonnes or heavier under mass management are finding they just don’t perform on the hills like the 600hp/ 2050lbft versions. And that shouldn’t come as a surprise to anyone because we’re in the fuel economy race not the horsepower race.”
Mike goes on to stress there is an optimum point of balance in terms of finding the right gearing for a specific application, taking into account weight and terrain, and that the IPC is being developed to optimise fuel efficiency in east coast linehaul B-double applications at typically around 60 tonnes.
“It’s not optimised for performance,” he asserts, “so customers with time-sensitive freight or those with mass management who could be grossing 68 tonnes have other options for better gradeability like using 3.9 diffs or the 600hp/ 2050lbft calibration.”
As we travel, Mike reiterates that achieving the best possible fuel efficiency in real-world conditions is the objective of the current testing regime. However, he stresses that the truck needs to be driven at the speed limit to ensure a good average trip time reflecting that of a typical express freight operator.
Therefore, I set the SmartCoast-enabled adaptive cruise control to 100km/h and that is the speed the truck maintains where road and traffic conditions allow.
By way of explanation, SmartCoast is the Cummins version of eco-roll whereby the computer senses when the vehicle is on a downgrade sufficient to maintain the pre-set cruise speed without any engine input and shifts the transmission into neutral. As the grade diminishes, the computer senses the loss in velocity, engages top gear and re-applies the appropriate level of engine urge to resume 100km/h.