Cummins meets high-torque Class 8 demand with Meritor RPL35+ driveline

Class 8 trucks continue to evolve toward more efficient powertrain operations, and one common strategy is down speeding, where the engine operates at lower RPM while maintaining highway speed. That approach requires the engine to produce higher torque and typically uses faster, numerically lower axle ratios to keep the vehicle moving efficiently at cruising speed. The driveline is the critical link that transfers torque from the engine and transmission to the wheels. As torque demands increase, Cummins says fleets and OEMs need driveline solutions that support fuel efficiency, uptime and lower total cost of ownership without adding complexity.

The RPL35+ is built on the proven legacy of the Permalube RPL series, which Cummins says is a trusted driveline platform specified by major North American OEMs. It carries forward the durability, capability and performance fleets expect from RPL products, with a permanently lubricated, sealed-for-life design that helps minimize maintenance needs. Cummins describes the RPL35+ as the next step in high-torque driveline design, building on that platform with changes that reduce weight, simplify service and support long-term durability. Designed for linehaul and heavy-duty service environments, it has been validated through field testing in demanding real-world applications, and Cummins says moving from the current RPL35 design offers a seamless transition while maintaining familiar service intervals and maintenance practices.

Cummins reduced weight by replacing the previous solid steel spline design with a hollow spline sleeve, removing excess material while maintaining the strength needed for high-torque applications. The redesigned coupling yoke eliminates traditional flange connections and associated hardware, reducing part count and simplifying assembly. Involute splines provide more contact area, enable smooth operation and improve noise, vibration and harshness characteristics. The hollow design also allows internal pressure to equalize naturally, removing the need for a diaphragm.

Cummins says fleets need powertrain components that can do more without making trucks harder to maintain, and the RPL35+ is designed to simplify service without adding new maintenance requirements. Because the driveline is lighter, it is easier for technicians to handle during installation and removal, and simplified connections reduce the number of parts involved in service. Traditional designs relieve internal pressure through a diaphragm, while the RPL35+ allows pressure to equalize naturally inside the shaft, eliminating the diaphragm and reducing system complexity. Fleets can adopt the RPL35+ without changing service intervals or maintenance practices. Cummins says improving the driveline at the component level helps fleets support efficiency, reliability and cost control and get more value from every mile.