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Mechanically, the transmission contains the widest overall gear ratio in its class and the weight was reduced 199 lb (90 kg) compared to the previous option. (image: PACCAR)

PACCAR launches lightest heavy-duty automated transmission for on-highway CVs

PACCAR has announced a new 12-speed automated transmission (AT) and column-mounted shifter to improve fuel economy and driver ergonomics in Peterbilt and Kenworth models in North America beginning in October. The transmission and shifter were jointly developed to provide a superior shifting experience while reducing weight.

“The PACCAR Transmission offers best-in-class performance, reliability and low cost of operation,” said Kyle Quinn, Peterbilt general manager and PACCAR senior vice president. “With the availability of this innovative PACCAR Transmission, the proven MX-13 engine and the efficient PACCAR Axle, the Peterbilt Models 579 and 567 can now be spec’d with the industry’s most advanced proprietary drivetrain.”

Paccar and Eaton teams co-developed the transmission over a three-year span. Eaton will manufacture the proprietary Paccar AT at its Mexico facility.

All-new platform

The transmission was developed for line-haul applications up to 110,000 lb (50,000 kg) Gross Vehicle Weight. It is designed to handle engine ratings up to 510 hp (380 kW) and 1850 lb·ft (2500 N·m) and features integrated electronic communications with the PACCAR MX engine. An industry-exclusive fluid pressure sensor provides advanced warning of low oil situations while an oil-coalescing air filter protects the transmission from contamination. It also has advanced predictive features that are able to select the starting gear and make shift decisions based on grade, vehicle weight, engine torque and throttle position.

Mechanically, the transmission contains the widest overall gear ratio in its class and the weight was reduced by 199 lb (90 kg) compared to the previous Eaton UltraShift option. It also boasts a cooler-less design that only requires 16 pints (7.5 L) of oil—“nearly half of what similar transmissions specify,” a spokesperson said—while providing extended maintenance intervals. Other features include a maintenance-free organic clutch, which reportedly has better control than the dual-plate ceramic clutch on the UltraShift, and an internally routed electrical system to maximize durability. These driver-focused decisions lead to class-leading low speed maneuverability and smoother, more intuitive shifting, the company claims.

Peterbilt is so confident in its proprietary drivetrain the company backs it with a comprehensive five-year or 750,000-mi (1.2 million-km) warranty.

“Since the transmission is an all-new platform, it provided us the opportunity to take weight out of the transmission,” the spokesperson said. “It is the lightest 1850-lb·ft capable heavy-duty automated transmission on the market. The team spent a lot of time optimizing the engine-transmission package.”

New shifter improves ergonomics

To accompany the drivetrain, a new column-mounted shifter will be standard on Peterbilt trucks equipped with the PACCAR transmission as well as those equipped with Eaton Advantage and UltraShift options. Relocating the shifter to the column was another driver-focused decision to improve ergonomics. It should make it easier to select the transmission gear and operate the engine brake whiling keeping the driver’s eyes on the road. This location also should provide easier movement back and forth from the seat to the sleeper area.

“The column-mounted shifter takes the ergonomics of the Models 579 and 567 to a new level,” said Scott Newhouse, Peterbilt chief engineer. “The column-mounted shifter was designed based on in-depth studies of driver behavior and ergonomics. This new design also allowed us to improve on the usability of our dash by eliminating engine brake control switches.”

Both the PACCAR automated transmission and column-mounted shifter are now available to order on trucks when paired with the MX-13 12.6-L inline 6-cylinder engine. Availability with the smaller 10.9-L MX-11 engine is expected for early 2018.

According to a Peterbilt spokesperson, these features are being released at a time when they see growth in the adoption of automated transmissions on the domestic line-haul market. The company now boasts a completely integrated proprietary powertrain with improved fuel economy and driver ergonomics.

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