Driving the International ProStar, with Cummins-Eaton powertrain

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Truck News / September 29, 2014

No, it’s not the SmartAdvantage. But it's a good example of a collaboration between Cummins and Eaton that is winning fans among Canadian fleets.

Cummins and Eaton have been cozying up of late in an attempt to ensure their future success in an increasingly vertically integrated world. The greatest example of this heightened level of collaboration comes in the form of the SmartAdvantage powertrain, which combines the Cummins ISX with an optimized Fuller Advantage Series automated transmission. That package has met with some success in the US market but is currently limited to a GVWR of just 80,000 lbs, constraining enthusiasm in the Canadian market, where greater payloads are often sought.

A lesser-known example of Cummins integration with Eaton comes in the form of the ISX15 mated to an Eaton UltraShift Plus LSE 16-speed automated transmission, which is approved for GVWRs of up to 110,000 lbs, offering a more versatile powertrain for Canadian fleets. The LSE stands for line-haul small step efficiency, and it’s this short 17% step between gears that allows for quick, precise shifting, enabling the driver to spend more time in the engine’s money-making sweet spot. The UltraShift Plus LSE was initially offered only in International trucks with Cummins or MaxxForce engines, but that exclusivity period came to an end in August, meaning we could soon see this combination offered by other OEMs.

The Canadian customers who have been running this spec’ seem to like it. Challenger Motor Freight took delivery of 10 International ProStar tractors with the ISX15/UltraShift Plus LSE package about a year ago and they’ve been run hard, put into service as team trucks running Ontario-B.C. I had the opportunity to drive one of these trucks and the odometer, after just a year in service, had already surpassed 300,000 kms. I took to the back roads around Kitchener, looking for elusive hills, and then spent some time on the 401. I was pulling a load of canned peas, grossing just shy of 80,000 lbs, considerably less than what this combination can handle.

Traditional transmissions have a step of about 35% between gears, making each step about twice as tall as those within the LSE. The contrast was noticeable when driving, especially when accelerating from a stop. The LSE charged through the gears, getting up to top gear quickly, usually starting from second gear and then skipping third, fifth and seventh along the way.

During my drive, Brent Talbot, territory sales and service manager with Eaton rode along in the bunk. He told me the traditional strategy of getting into top gear quickly and staying there as long as possible has been replaced with the idea the driver should instead focus on getting into the sweet spot and remaining there, even if it means running in 15th gear at times. I spent most of my drive in 16th, so these aren’t mutually exclusive scenarios.

When we think of manual or automated transmissions, we tend to think in terms of 10-, 13- and 18-speed gearboxes.

But the 16-speed UltraShift Plus LSE strikes a nice balance for Canadian fleets looking for a versatile transmission that performs admirably and is well integrated with the Cummins engine. The ISX/LSE combo provides fleets with the versatility they require when hauling loads ranging between 80,000 and 110,000 lbs; there’s less risk of dispatch deploying the wrong truck to pick up a load that’s heavier than what the truck is rated for.

The ISX/LSE doesn’t downspeed to the same extent as the SmartAdvantage. While the SmartAdvantage allows the engine to cruise at just 1,200 rpm, the ISX15 I drove cruised at 62 mph at a higher 1,380 rpm.

Still, the integration between engine and transmission runs deep enough to provide a high-performing alternative to the SmartAdvantage while a more robust version approved for 110,000-lb GVWRs continues to be developed. The ISX15 I drove produced 450 hp and 1,650 lb.-ft. of torque, which was more than enough for southern Ontario and also sufficient to conquer the Rocky Mountains, one would presume – otherwise Challenger wouldn’t be sending it there every week.

Downspeeding aside, there are a couple of factors that contribute to the efficiency of the ISX15/UltraShift Plus LSE package. For starters, the UltraShift Plus LSE is a direct drive transmission, which generally improves fuel economy by 2% compared to an overdrive, since parasitic losses within the transmission are eliminated. Customers who’ve spec’d the ISX15/LSE powertrain have seen fuel economy gains compared to say, an ISX15 with a 13- or 18-speed automated overdrive transmission, according to Adam Whitney, national account executive with Cummins, who was also along for the ride.

Cummins contends its ISX15, despite its higher displacement and greater bulk, is generally more fuel-efficient than a 13-litre, especially in Canada where a 13L has to work hard when making cross-country trips.

“A lot of that comes down to, it’s not working at its maximum efficiency – it’s not working as hard as a 13-litre,” Whitney said of the ISX15.

Cummins and Eaton have collaborated in an unprecedented manner to ensure this engine and transmission are optimized to work together and this partnership has translated into noticeably improved performance.

“Historically, we wouldn’t have shared our fuel maps but now we do with Eaton,” Whitney explained. “They know exactly where we want to be rpm-wise, where it’s going to be more fuel-efficient and they have optimized the shift points.”

The UltraShift LSE makes smooth, quick shifts at just the right time, allowing the ISX15 to run in its intended sweet spot to perform to its full potential.

Unlike the new Fuller Advantage Series automated manual transmissions, from which Eaton has eliminated the oil cooler to save weight, the LSE still requires a cooler.

“It has a higher capacity gross weight, rated up to 110,000 lbs, and at that level if a customer were to maximize his gross weight he’s going to need a cooler to maintain the transmission’s operating temperatures,” Talbot explained.

The ISX15 in the ProStar I drove was incredibly quiet, which I’m sure is appreciated by whichever team driver occupies the bunk at any given time. Whitney says the Cummins high-pressure common rail fuel system contributes to its low noise output.

It also features a highly effective engine brake, which is assisted by the variable geometry turbocharger to maximize its braking power. If you want to get the most available engine braking you can put the transmission into low gear when approaching a stop. (It’s an automated, but you can still override this transmission by selecting M for manual or L for low on the shift console. When doing so, the transmission will defer to you – as long as you don’t try something stupid that would hurt it).

Why shift to low gear when approaching a stop? “It’s going to move your downshift rpm points out to the governed rpm where the engine brake is strongest and it will continue to downshift right down to first gear,” Talbot explained. “You can take it out of low and put it back into drive or manual and continue driving at any time.”

This feature works exactly as advertised. Just ask the guys in the bunk, who asked me to give them a warning next time I put it in low.

Other features of the UltraShift Plus LSE that contribute to its drivability include a grade sensor that’s integrated into the electronic control module. This allows the transmission to hold the truck’s position on hills for up to three seconds to eliminate rollback when the driver is moving his foot from the brake to the accelerator.

“It also allows us to make much better shift selections because knowing what the horsepower and the torque maps of the engine are as well as the throttle position, we can calculate the weight of the vehicle to within a couple thousand pounds,” Talbot explained. “And if you know the weight of the vehicle and you know the grade you’re on and you know the torque and horsepower maps, you can make very intelligent shift decisions.”

The ISX15 delivers peak torque right down to 1,000 rpm, often preventing the need for downshifting.

The ISX15 I drove did not have SmartTorque enabled, which would have provided another 200 lb.-ft. of torque in the top two gears when needed. That’s a nice option to have but some fleet buyers like Challenger opt not to select it, probably because SmartTorque could contribute to a small uptick in fuel consumption when employed.

The UltraShift Plus LSE skip-shifted readily in the lower gears and why not?; the short step means it can jump gears like Eric Lamaze jumps Spruce Meadows fences.

Navistar International has had its detractors in recent years, resulting from its ill-advised emissions strategy that backfired in a big way. But throughout its ordeal, no one had an unkind word to say about the ProStar. It’s been a while since I’ve driven one and I was reminded that this is a nice, comfortable truck to drive with good visibility, a quiet interior and a steady ride.

The quiet, steady attributes are likely what make it a popular team truck. The UltraShift Plus LSE gave International a differentiated product, even though its exclusivity was just temporary. It seems to have done a decent job of getting this truck out into the market.

“International has done a tremendous job of selling it,” said Whitney, noting other well-known fleets such as Contrans have recently been taking delivery of ProStar trucks featuring this same powertrain.

As OEMs continue to espouse the benefits of vertical integration, independent component manufacturers such as Cummins and Eaton have not sat idly by and watched demand for their products erode. They’ve been working more closely together than ever before to ensure they can deliver the benefits of integration, even as separate suppliers. The ISX15 with UltraShift Plus LSE is another example of this conjoining of expertise, and it’s one that seems right at home here in Canada.

The spec’s:

ENGINE: Cummins ISX 15 450, EPA 2010 450 HP @ 1800 RPM, 1650 lb-ft Torque @ 1000 RPM, 1800, RPM Governed Speed, 461 Peak HP (Max)

TRANSMISSION: Eaton Fuller UltraShift+ F-17E316B-LSE 16-Speed Fully Automated Manual; With Aluminum Clutch Housing, Direct Drive, Electronic Shift Controls, Electric Clutch Actuation, Air Range Shift, Internal Lube Oil Pump, Hill Start Aid

CLUTCH: Eaton Fuller ECA-1850 Two-Plate, Ceramic, 7-Spring with Pre-Damper, 15.5″ Diameter, with Adjustment-Free Feature, 1850 lb-ft Torque Capacity

AXLE, FRONT NON-DRIVING: Meritor MFS-13-143A Wide Track, I-Beam Type, 13,200-lb Capacity

AXLE, REAR, TANDEM: Meritor MT-40-14X-3CFR DualTrac, Single Reduction, 0.374″(9.5mm) Wall Housing Thickness, 40,000-lb Capacity, R Wheel Ends, With Amboid Gearing in Rear Rear Axle Gear Ratio: 2.64

CAB: Conventional, Sky-Rise Sleeper Cab; 73″ Seat to Inside Back of Cab, With 42″ Wide Bunk

TIRE, FRONT: (2) 275/80R22.5 XZA3+ (MICHELIN) 517 rev/mile, load range G, 14 ply

TIRE, REAR: (4) 445/50R22.5 X ONE XDA ENERGY (MICHELIN) 518 rev/mile, load range L, 20 ply

SUSPENSION, REAR, AIR, TANDEM: International Ride Optimized Suspension (IROS) Heavy Duty; 52″ Axle Spacing; 40,000-lb Capacity, 9.25″ Ride Height, Includes Heavy Duty Spring Hangers, Crossmembers and Fasteners.