A rear axle that’s fit for the world’s best powertrain

Scania’s new rear axle gear is no exception to this perfectionism.

“We’ve managed to present a killer component. This is a rear axle that fits the world’s best powertrain. In fact, it is an integral part of it,” says Torvald Ilg, Chief Engineer within Axles and Propulsion Development at Scania and one of the developers that has been working on the rear axle programme.

“It’s great to design a component that makes the driver a bit happier each time he or she fills up the tank,” he adds.

The new rear axle gear – an all-round single reduction axle – is the first to be released in an entirely new rear axle programme that has a focus on improved efficiency. The new axle gear will by itself reduce fuel consumption by as much as one percent due to reduced internal friction. And together with increased gear ratio spread of the G33 and G25 gearboxes, there is the potential for additional fuel savings through the use of faster rear axle gears.

“We’ve put an enormous amount of engineering resources into this to be able to reach that one percent. By its very definition, a rear axle has significant energy losses. But by smart design measures we have managed to lower the losses by 35 percent. That’s a great achievement,” says Ilg.

So, how did Scania’s R&D team manage to improve the efficiency of the new rear axle? The axle housing is new and lighter than the previous model. Special, low friction

bearings are used throughout, which is especially important on the pinion gear. What’s more, the parts have tighter tolerances and are more smoothly machined in production, leading to minimal energy losses.

“We also put a lot of effort on reducing losses from oil splash,” says Ilg.

He adds that the team’s solution for that particular challenge includes a splash plate in the axle that collects some of the oil volume when the vehicle is moving at higher speeds. This is suitable since the load on the gear is usually lower in this type of operation.

“The oil will slowly flow back to the bottom of the gear house through holes in the plate when the speed is lower. Therefore, the oil level will be higher in the gear house when the oil is no longer lifted up to the axle shafts by the crown wheel,” he says.

Torvald Ilg says his team has had close contact with the other Scania developer teams, who are focusing on the new 13-litre Super engine platform, the new gearbox, new tanks and more flexible chassis, respectively.

“We’ve had great interactions with the other teams, and our discussions have constantly focused on how we all can contribute to reduce fuel consumption and how we can integrate new features into specific components to improve the performance of the whole powertrain.”