A perfect match between engine and gearbox

26 JANUARY 2022

Scania’s new gearbox is key to realising the fuel-saving potential of the Super engine platform. Light, compact, smooth and quick, it is the perfect match for the new 13-litre engines.

When Scania’s engine developers were pushing the limits to create the cleanest and the leanest combustion engine platform the world has ever seen, they had to give it the best possible conditions to fulfil its full potential. That’s why, even at an early stage in the development project, there were tight connections between Scania’s engine developers and their transmission and gearbox colleagues.

“This approach made it possible for us to design the new powertrain totally from scratch, with a holistic perspective,” says Peer Norberg, Senior Engineer in Scania’s transmission development team.

Per Arnelöf, Expert Engineer, Scania gearbox development, adds:

“It was extremely motivating for us to have the initial discussions with the engine technicians and to realise how far you can actually go with an internal combustion engine when it comes to efficiency. From the very start, our focus was not only on designing a cutting-edge gearbox, but to optimise the whole powertrain to meet the customers’ demands. The result is a perfect match between the new gearbox and the Scania Super engine platform.”

Industry-leading fuel-efficiency

The technical solutions of the new G25 gearbox are basically the same as those of its larger sibling, the G33, that was launched two years ago as the first in Scania’s new gearbox platform. The main characteristics are also the same: a compact, light, and super-efficient 12+2 automated gearbox that matches Scania’s industry-leading and fuel-efficient low rev-high torque philosophy.

“Many features of the new G25 gearbox were introduced already with the G33 but what’s great is that we manage to take it a step further; for example, when it comes to reducing internal losses,” says Norberg.

Arnelöf adds: “The new gearbox changes gears in a fantastic way. It’s responsive, quick and smooth. And as we also worked on the sound characteristics, it’s also very quiet; it doesn’t have the predecessor’s hisses and clanging.”

Increased gear ratio saves fuel

A key feature of Scania’s new gearbox platform is its increased gear ratio spread: 60 percent more than the previous GRS905 model. This makes it possible to optimise the rear axle gear for low engine revs in cruising speed without sacrificing startability. That’s good news for fuel consumption and the climate.

“We make it possible to take further steps towards low engine revs. You can cruise on the highway in 80 km/h on gear 12 and then shift to overdrive in slight downhill conditions, coming down to an amazing 850 revs,” says Arnelöf.

“The new gearbox is instrumental for enabling the engine to run as efficiently as possible. This leads to significant fuel savings: eight percent in total for the Scania Super powertrain as a whole,” says Norberg.

Amazing feeling to see that everything worked

Both Norberg and Arnelöf have fond memories from the Scania Super development process, with more than two billion euros spent, one of Scania’s largest investments to date.

“I particularly remember when we first installed the new gearbox in a vehicle, sitting in the cab, putting in the reverse gear and taking the truck out from the workshop. The feel when everything just worked was amazing,” says Norberg.

In short: Scania’s new G25 Opticruise gearbox

The gearbox platform itself offers fuel savings of 1%.
With a 60% increased gear ratio spread compared to previous GRS905 model, the powertrain efficiency can be further improved by optimized engine speed.
Maximum torque: 2,500 Nm.
Same platform and same technical solutions as G33 (3,300 Nm).
Number of gears: 12+2 (Super crawler and Overdrive).
Number of reverse gears: 8.
Improved uptime, with an oil change interval of up to 1,000,000 km.
More compact and 75 kg lighter.
Improved freewheeling retarder.