Peterbilt Announces New Medium-Duty Trucks and Transmission, Updated Engines

Peterbilt 535 and 536
Peterbilt's 535 and 536 models (Peterbilt)

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Peterbilt Motors Co. announced two new medium-duty box truck models — the 535 and 536 — aimed at the lease and rental segment; and two other models — the 537 and 548 — intended for the vocational “Class 7/8 market” that allow for multiple body builder integrations.

The truck maker also launched its all-new Paccar TX-8 eight-speed automatic transmission and updated its PX engines.

The new trucks, transmission and engines are available for ordering with deliveries scheduled to start in July, according to the Denton, Texas-based company, a unit of Paccar Inc.


The Peterbilt 537 dump truck. (Peterbilt)

“This year has proved to be a very big year for Peterbilt, first with the launch of the new model 579 [its Class 8 on-highway flagship truck in February] and now with launch of the new Model 535 and Model 536,” Jason Skoog, Peterbilt general manager, said in a release.

“The medium-duty segment is integral to Peterbilt’s business and we have seen great gains in market share since the launch of our first medium-duty truck back in 1995,” Skoog said. “These trucks are a perfect fit for the growing lightweight lease, rental and pickup and delivery markets with their versatility, excellent efficiency and uptime.”

He noted the larger model 537 and 548 trucks “are fine-tuned for their specific application, not to mention have the durability and toughness to be around for a long time.”

Skoog said in an online presentation that Peterbilt has sold more than 100,000 medium-duty trucks in the United States and Canada since 2010. Peterbilt launched its initial medium-duty truck, the model 330, in 1995.

Peterbilt started with what it called a “clean sheet of paper” and said the new trucks emerged from a five-year project that involved extensive customer feedback.

All the new truck models share some common features, including: a wider cab, stair-style steps and knurled grab handles, 4.6 cubic feet of storage space, three cup holders, a dash layout with available space for optional gauges, switches and ram mounts.

Driver information is presented with an analog speedo and tachometer and a high-resolution 7-inch digital display integrated into the electronics of the truck with the appropriate information such as system check, trip summary, power take-off functions, safety systems and tire pressure monitoring systems. Drivers are able to toggle through menu cards on the digital display utilizing the new multifunction steering wheel and the display navigation knob.


Drivers are able to toggle through menu cards on the digital display utilizing the new multifunction steering wheel and the display navigation knob. (Peterbilt)

On Class 5 and Class 6 models, measurement from the bumper to back of cab can be either 107 inches or 109 inches and the trucks offer a turning radius of 51 feet.

In addition, their rear suspension is available with a taper-leaf or air-leaf suspension rated from 12,500 to 40,000 pounds depending on a single or tandem drive configuration (the 537 and 548 models do as well).

Options available on the 535 and 536 models include two hood lengths, two roof heights, composite and steel bumpers, as well as multiple options of fuel and DEF tanks.

Options on the 537 and 548 models include a vocational three-piece Metton hood featuring a stationary grille with full through rail, and a three-piece sheet molding composite hood for maximum visibility. Both hood options can use a variety of vocational and front engine power take-off bumpers to fit different applications.

The 537 and 548 models’ suspensions also offer wide or standard track axles featuring wheel cut angles for a shorter turning radius and mono-leaf or taper-leaf front springs rated from 8,000 up to 20,000 pounds.

Meanwhile, the new transmission monitors changes in road grade, vehicle acceleration, torque demand, weight and engine load to keep the truck in the most fuel-efficient gear, Peterbilt reported. What it called “industry-leading shift performance” delivers automotive-like shifting with up to 5% better fuel economy, compared with earlier models.


A view of the driver's seat and bench seat. (Peterbilt)

The transmission also has an Auto Park Lock system, a safety feature that automatically engages the park lock should a driver forget. There’s a twin torsional damper that enables early first gear lock-up for smoother shifts and faster acceleration. Finally, the mechatronic unit and transmission control unit are combined into one unit within the oil pan for ease of service.

At the same time, existing Paccar powertrain components will be rebranded to align with the newest member of the family. All transmissions will take on the TX designation with the 12-speed being renamed the TX-12.

Paccar’s 40k drive axle will become the DX-40 and the vocational 20k front steer axle becomes the FX-20.

“Future components will continue the trend of integrated efficiency and performance across more segments of the market,” Skoog said.

In 2020, Ford Motor Co. had the highest share of U.S. retail sales for Class 5 and Class 6 trucks. Freightliner, a unit of Daimler Trucks North America, led in Class 7 and Class 8 sales, according to

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