Q&A: What It Takes to Add an E-Axle

Linamar, Bosch show off new e-axle tech for larger trucks.

September 12, 2024

Sebastian Blanco

Boach and Linamar collaborated to install an electric drivetrain and Linamar’s new e-axles into this modified Dodge Ram 2500. (Bosch)

During a recent Bosch tech showcase, we spoke with Joe Leaf, engineering manager for electric propulsion systems at Linamar. The Guelph, Ontario-based parts manufacturer is no stranger to building unsung components for the auto industry, including gears, camshafts, connecting rods, and cylinder heads. The Linamar team was demonstrating a modified Dodge Ram 2500, a collaboration between Bosch and Linamar, that was outfitted with a prototype electric powertrain and new e-axles: a rigid axle on the rear (with a Bosch motor and inverter) and a steering axle up front.

SAE Media: Tell me about the reason for this project. Why are you working on these particular axles? Why are you showing them off today in this truck?

Leaf: The class 3 and 4 segments are expanding pretty quickly with electrification. Municipalities in places like California are required to go all-electric at some point very soon, so they’re looking for an application like this. We thought it’d be best to get into that market. We currently have class 5 and 6 production axles available, but the goal was to demonstrate what we could do with class 3 or 4 as well.

We’re pretty good at making gears and drivetrains, so that wan, just getting everything to play nice together and start up [o plao that as well. We had to talk to the electric system instead of the gas system. The vehicle ECU is going to try to talk to an engine controller, which you don’t have anymore." We had to take and replace the entire electrification system from the control perspective because the axle is just looking for a torque.

SAE: This is well designed for either a hybrid, an electric or a hydrogen system, and that’s where the whole industry is going. How is Linamar preparing for the powertrains that are coming?

Leaf: Architecture is a big thing for your hybrids, particularly because they’re putting motors in the front of the vehicle. In this axle, everything is compacted into the center section. Well, now I don’t have that space because I have an engine that sits there, so you have to go to different gear designs, typically coaxial, instead of the parallel axis. From a packaging perspective, it’s very challenging. And then, of course, it has to have the ground clearance. It has to be narrow enough, and then you have a big old engine coming through the middle. The rear is pretty much free space. There’s not a lot back there to get in your way, so you’re a little bit more free to do different designs there. Packaging is tough.