Paccar’s latest automated transmission, the TX-18, is a new vocational design for on- and off-highway applications. It's an expansion of the TX line that launched last year with the TX-8 and later the TX-12.

The TX-18 is optimized for on-highway, high-performance and mild vocational applications, and the TX-18 Pro is engineered for on- and off-highway work in mild to severe applications.

The new transmissions will be available beginning this July for the following models equipped with Paccar MX-11 and MX-13 engines:

Kenworth

• T680 Next Gen

• T880

• T800S

• W990

Peterbilt

• Model 567

• Model 579

• Model 389

In a news release, Peterbilt called the TX-18 “the perfect workhorse for a variety of vocational applications including heavy haul, dump truck, and cranes.”

Kenworth noted that the transmission was engineered to operate with the Paccar MX engine platform and maximize the full potential of all MX engine ratings, with maximums of 510 hp, 1,850 lb.-ft of torque, and 140,000 lbs. gross combination vehicle weight.

Digging into TX-18 Details

Kenworth gave reporters a sneak peek of the new TX-18 during a preview of its new electric and hydrogen fuel cell trucks in Sunnyvale, California, in January. The event included a Kenworth T680 outfitted with a TX-18, which was available for brief drives in city traffic. (Read Jack Roberts' experience with the TX-18 Pro.)

The main launch for the new transmissions was handled by sister Paccar company Peterbilt a couple of weeks later at the Eaton Proving Grounds outside of Marshall, Michigan. The TX-18 was developed with Eaton.

The TX-18 is designed for heavy-duty applications, with both versions rated up to 140,000 pounds GCWR, Kyle Crawford, vocational product manager for Peterbilt, said during the pre-drive briefing on the new transmissions. "So it’s designed for heavy-duty applications like off-highway construction, heavy-duty wreckers, and fleets that haul in mountainous terrain and need a little more power and performance to deal with those conditions.”

Features include an extreme-duty clutch, an 1,850 lb-ft torque rating, plus six reverse gears for the extreme-duty TX-18 Pro.

“Those six reverse gears on the TX-18 are combined with a standard dual power-takeoff (PTO),” Crawford added. “The PTO provides 75 to 160 horsepower and can be operated while driving. When combined with the TX-18’s six reverse gears, it makes it an excellent choice for rock-spreading applications.”

Additionally, Crawford said, the TX-18 design features a 47% reduction in parasitic losses and is 225 lbs. lighter than competitive automated transmissions on the market. It also features predictive cruise control, is fully integrated with current Paccar powertrain technology and systems, and can be programmed with four different application-specific calibrations to ensure peak performance in difficult applications.

Other important vocational features include:

• An integrated clutch housing

• A transmission cooler option for GCWR ratings under 110,000 lbs.

• Internal wiring and sensors for added protection from the elements and enhanced uptime

• A standard oil temperature sensor

Driver feedback has been positive, Crawford noted. “Drivers tell us they like the transmission’s excellent low-speed maneuverability, its small and even gear steps, and its simple, easy-to-use, next-generation controls which include a stalk-mounted shifter.”

Another important feature Crawford pointed out is the TX-18’s “optimal” clutch engagement for hill-starts — even with 160,000 lbs. on a flatbed behind the truck.

“The AMT automatically holds the truck still when the brake is released, and then selects the best gear possible to start and gain speed going uphill,” he explained. “The transmission will also automatically select the proper gear for holding the truck at a steady speed on down grades. This is a big benefit from a safety standpoint, while helping reduce driver fatigue. It also helps expand a fleet’s potential driver pool by making good drivers even better in difficult terrain conditions.”

The Paccar TX-18 transmission features a high-pressure diecast aluminum casing, one-piece serviceable input shaft, helical gearing, precision lubrication system, extreme-duty clutch and an integrated clutch housing. It can be configured with an optional transmission cooler to help keep it operating efficiently in highly demanding applications. The transmission features four application-specific calibrations and comes standard with two PTO openings capable of a combined 160 hp.

 Paccar TX-18 and TX-18 Pro Quick Specs

Max. Horsepower 510 hp Max. Torque Capacity 1,850 lb.-ft   Max. Operating Weight (GCVW) 140,000 lbs. Unit Weight 808 lbs (TX-18) / 813 lbs (TX-18 Pro) Oil Capacity 25.4 pints (12L) Maintenance Intervals (on-highway): 500,000 miles / 5 years Vocational Lube Interval: 250,000 miles / 3 years Clutch Maintenance-Free 

Correction: Updated 9:45 EST to clarify that the TX-18 is not based on the medium-duty TX-8 model, which was produced in partnership with ZF for Kenworth and Peterbilt's new medium-duty trucks.