CUMMINS delivers on a lighter Class 8 driveline

How the new RPL35+ was engineered to reduce weight without conceding on any other factors - and why the hollow spline sleeve at its core took three years to get right.

North American Class 8 driveline engineering has long balanced torque capacity, durability and NVH against weight - with weight typically the constrained variable, not the primary driver. That balance is shifting.

Lightweighting has been a serious engineering discipline in commercial vehicle drivelines for decades, particularly in markets where GVWR/GCWR limits are tighter and fuel costs higher. In North America, the market has historically been somewhat different: payload regulations are less punitive, fuel is relatively cheaper, and the premiums on torque capacity and durability in demanding vocational and linehaul applications typically outweigh the case for shaving driveline weight. Weight reduction has been an engineering objective, but rarely the primary one.