Spec'ing Tips for Medium Duty Trucks

Kenworth T370

KIRKLAND, Wash., July 24, 2015 – Medium-duty truck operators have heavy-duty expectations. Truck manufacturers are working to make it simpler for customers who want heavy-duty characteristics in traditional medium duty applications, including construction, refuse, liquid bulk, food and beverage distribution, highway maintenance, and fire and rescue. Companies that operate medium duty trucks seek a business solution that provides superior up-time, reliability and dependability. 

“These three factors are especially important in their truck choices. Day-in and day-out, medium duty trucks are work trucks that must make timely deliveries, pick-ups, or service calls in order to satisfy their customers,” said Kurt Swihart, Kenworth marketing manager. “The challenge in spec’ing a medium duty truck is to find the right balance between over and under spec’ing to achieve the performance and reliability required to get the job done on a daily basis.”
Here are five things to know about spec’ing a medium-duty truck for heavier weights and tough applications:
1. More Horsepower and Torque Ratings
A 9-liter diesel can produce a range of horsepower and torque ratings for applications that fall in between typical medium-duty and heavy-duty use with today’s engine technology and electronic controls.
For instance, the PACCAR PX-9 has ratings from 260 to 380-hp and up to 1,250 lb-ft of torque. Features like replaceable wet liners, roller cam followers, bypass oil filtration, and targeted piston-cooling are decidedly heavy-duty, yet the engine’s displacement and weight are ideal for the Kenworth T370, T440 and T470 trucks, which can be spec’d as a light Class 8 or a heavier-duty Class 7. At the same time, it's important not to spec more power than you need.
“Look at our Kenworth T370. Under most circumstances, the PACCAR PX-7 engine delivers plenty of power and torque for a Class 7 truck like the T370,” Swihart said. “It produces 200 to 325-hp with up to 750 lb-ft of torque from a 6.7-liter displacement, an excellent horsepower-to-weight ratio. With a bigger engine you’d start trading off fuel economy and weight.”
2. Higher-Capacity Front Axles
A lighter engine and higher-capacity front axle give you the ability to shift more weight to the front end and still have all the advantages of a short bumper-to-back-of-cab (BBC) measurement.
“We offer 18,000- and 20,000-pound front axles on Kenworth T370s equipped with a PACCAR PX-9 engine, a response to bulk fuel distributors, construction, refuse, dump truck operators, and other customers who not only want a true medium-duty truck, but also the ability to distribute the weight of payload to the steer axle,” Swihart said.
The heavier axle package comes with a heavy-duty, cross-brace-reinforced front frame assembly, bolted cross members, and either 10-3/4-inch frame rails or 10-5/8-inch frame rails with inserts. Iron hubs, drum brakes, and dual-power steering gears, along with a power steering cooler, are part of the spec.
3. Operator-Friendly Transmissions
Automatic and automated transmissions allow fleets to hit the “sweet spot” in terms of drivability and fuel economy. One example, Swihart said, is the 10-speed Eaton UltraShift PLUS, a two-pedal solution for Kenworth medium-duty trucks that dramatically widens the driver pool and reduces training costs. 

Eaton UltraShift PLUS has an electronic clutch actuation system that enables quick shifts and clutch engagement regardless of engine RPM. It selects the right start gear and adapts shift decisions based on the driving environment so you get smooth automated shifting and vehicle launches.
Automatic transmissions continue to evolve and grow in popularity in the medium duty segment. Allison’s FuelSense feature has electronic controls that automatically adapt shift schedules and torque, maximizing transmission efficiency based on load, grade, and duty cycle. “We offer a multitude of FuelSense options to best suit each customer’s need, either for greater performance or for a fuel economy focus,” said Swihart.
4. Customized Approach
The truck dealer, body builder, and truck OEM have exceptional resources available to help you customize your spec so your vehicle is set up exactly the way you want it and is productive from the start.
“When you’re looking at truck and body suppliers, ask how the two communicate,” Swihart said. “Are they talking to one another and sharing ideas on a steady basis to make sure that the chassis and body come together as expected?”
A generation ago this process involved drawings and body-builder manuals being sent across the country, with fingers crossed that there were no mistakes or missed connections to delay the process. If you want to see what your chassis would look like with a horizontal crossover DPF with a ground-dump tailpipe and compare it to a DPF under the right-hand side of the cab with dual tailpipes, it can be done on the screen.

“Today, we’re sharing 3D CAD models that show crossmember locations, PTO locations and clearances, special frame drilling patterns, and other air, electrical, and emissions equipment on the frame,” Swihart said. “As a customer, you can visualize what your truck is going to look like right down to a fine level of detail before anyone drills the first hole.”
5. Lower Total Cost of Ownership
The biggest misconception about the medium-duty truck market is that you have to limit your choices or settle for a truck that’s not exactly what you need because price is an issue, Swihart explained.
“Let’s face it, this is a price-conscious market,” he said. “But price is only one factor in the total cost of ownership. The lower-priced truck may be more expensive to operate over time compared to a truck that costs more at the outset, but is more durable, reliable, and better suited to the task at hand. The low-priced truck probably won’t hold its resale value, either.”
Swihart’s advice to medium-duty truck owners: focus on the total lifecycle cost of the vehicle. Kenworth dealers can help you calculate a truck’s total cost of ownership, from the initial acquisition until it’s time to trade the vehicle in for a new one.
Kenworth Truck Company is the manufacturer of The World’s Best® heavy and medium duty trucks. Kenworth’s website is Kenworth.com. Kenworth is a PACCAR company.

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