Two-stepping through Texas
Up in the tractor and out on the road, the ProStar+ continues to impress. This model features International’s deluxe trim package, so the rich smells of plush leather seats waft over you as you slide behind the driver’s seat. The warm tones of wood panels and trim accent the well-lighted switches on the instrument panel, Itself highlighted by the middle console, which features International’s top-of-the-line stereo and GPS navigation system. Everything is within easy reach for the driver. And the stereo/GPS system is intuitive and quickly mastered.
International’s engineers have done a great job making the driver feel like he’s integrated into the overall design of the vehicle. And everything, from the instrumentation, switch placement, views over the hood and to the sides to the tight, responsive way the truck handles rolling down the road reinforces this feeling.
Another strong positive is the sound insulation in the cab. It’s clear that International designers worked hard to create an integrated, complimentary sound-dampening system that isolates both vibration coming up through the vehicle frame as well as wind, engine and highway noise. Of course, it doesn’t hurt that the MaxxForce 15 is an inherently quiet engine to start with, thanks to its compacted graphite iron design — lighter, stronger and quieter than conventional cast iron used in engine blocks.
This particular MaxxForce 15 is mated to an Eaton 13-speed manual gearbox — and believe me, that big engine gets the rig going fast: But once at cruise speeds, the MaxxForce 15 settles in at around 1,200 rpm and stays there. Even the occasional long climb up a deceptively shallow-looking Texas grade didn’t rile it up: In this environment, downshifting becomes optional for drivers: You can grab a lower gear if you want. But there’s really no need. The MaxxForce 15 might lose 4 or 5 mph starting up the rise, but by the time you’re halfway up the slope you’ll be right back on your target speed. And by the time you reach the top, you might find you’ve even gained a few mph, depending on how steep the grade is.
That won’t hold true in more extreme terrain, of course. But it’s solid evidence that this engine has the on-demand power to make a driver’s life a lot easier if the countryside will allow it.
After some incredible beef brisket at a truckstop north of Buffalo, it was time to turn the big ProStar+ back toward Big D and wrap up the test drive. My main takeaway for the day was a true appreciation for the overall MaxxForce 15/ProStar+ package. This is a truly integrated design, and the solid feel behind the wheel is a direct result.
International would be the first to admit that a 15-liter diesel isn’t for everybody. But if your application demands one, they’ve certainly got an engine that fits the bill. It’s got plenty of power when you need it but cruises as quiet as a kitten when brute force isn’t required. It’s a solid engine mounted under the hood of a solid tractor.
ProStar+ with MaxxForce 15 specifications
Model: PROSTAR+ 125 6×4
Engine: MaxxForce 15, 450 horsepower, 1,550/1,750 lb.-ft. torque at 1,000 rpm
Engine compression brake: MaxxForce for MaxxForce 15 engines
Transmission: Fuller RTLO-18913A 13-speed manual with double overdrive and internal lube oil pump
Clutch: Eaton Fuller Solo Advantage self-adjusting, two-plate, cast angle spring; ceramic, 15.5-inch diameter, soft rate damper, 1,860 lb.-ft. torque capacity with hydraulic actuation with air assist
Driveline: Dana Spicer SPL250XL plus SPL170XL inter-axle shaft
Brakes: Bendix Antilock Brake System, full vehicle wheel control system (four-channel) with automatic traction control
Front axle: Meritor MFS-13-143A wide track, I-beam type, 13,200-pound capacity
Rear axle: Meritor MT-40-14X-3CFR single reduction, 40,000-pound capacity, Amboid gearing in rear drive axle