Trucks: Caterpillar’s CX vocational automatic transmissions

If you’re a believer in fully integrated powertrains, spec’ing a Cat engine for your next work truck is about to get a lot easier. Next year, Caterpillar will begin offering two fully automatic, planetary transmissions designed specifically for vocational truck applications.

The timing of Cat’s announcement is potentially frustrating for some North American heavy truck manufacturers who would like to see vertical integration of their product lines become the norm. Vertical integration of truck components means the OEM limits the number of components a customer can spec for a new truck; in many cases these choices are restricted to components manufactured by the OEM or its sister companies.

The practice is common in Europe – and in the North American automobile industry. When’s the last time you selected a specific brand of axle for your SUV, for example? But it’s a plus for truck manufacturers, who say it lets them fully integrate all of a truck’s systems – engine, transmission, suspension and axles – for optimum vehicle performance. It also keeps production costs down since the OEM doesn’t have to purchase outside components or engineer the truck to accept a wide array of components that can have widely differing installation requirements.

American customers, though, like being able to pick and choose the components they feel will give them the best combination of performance traits to meet their particular hauling needs. And according to Cat, it’s these very customers who have been calling for it to enter the truck transmission market. “Customers and original equipment manufacturers have been asking Caterpillar for years to provide automatic transmissions that can be matched with Cat on-highway engines they are already buying,” notes Chris Schena, vice president, Caterpillar. “When matched with a Cat engine, these new transmissions will deliver improved performance, fuel economy and reliability while giving North American truck owners another choice in the marketplace.”

“We can now offer truck owners a complete Cat powertrain,” adds Walt Hupe, general manager, Caterpillar transmission group. “Every component has been engineered to perfectly match each other. The electronics system, the torque converter, transmission and engine function as an optimized package and we feel this is what gives us an advantage over other automatic truck transmissions available today.”

Lighter case, new shift points
Cat has dubbed its new on-highway transmissions the CX Series. Two initial units will be offered – the six-speed CX31 and eight-speed CX35. Both transmissions were developed for Caterpillar’s 700 Series articulated dump trucks. “The transmissions are sealed in cast-iron cases for that application,” Hupe notes. “We’ve developed a lighter weight aluminum case and changed the transmission shift points for on-highway use. But other than that, the interior componentry is identical.”

The aluminum casing offers CX automatic transmissions considerable weight savings – up to 900 pounds – when compared with the off-road variants. Both models have higher power PTO options, including a clutched PTO or output yoke and live pump mount configurations. You can spec traditional eight- or one o’clock drives, or a new rear-drive PTO.

Hupe says Cat focused on easing CX transmission service demands too. Both units feature exterior-access control valves and spin-on filters and can be diagnosed using Cat’s ET service tools with programmable electronic control module (this same system can be used to diagnose Caterpillar engines as well).

Truck manufacturers contacted about the new transmission line say they’ll let North American customers decide which transmission to spec in their trucks, but note that supplier talks are in very early stages.

CX31 transmission

  • Six forward speeds
  • Rated up to 500 horsepower
  • 1,650 pounds-feet of torque
  • Integral retarder
  • Engine matches: C11, C13 and C15 (up to 500 horsepower)

CX35 transmission

  • Eight forward speeds
  • Rated up to 625 horsepower
  • 2,050 pounds-feet of torque
  • Integral retarder
  • Engine matches: High-horsepower C15 versions and C18 off-road