Clean, efficient, and low-cost: MAHLE optimizes combustion engines for commercial vehicles with variable valve train

Stuttgart, August 7, 2018 – Variable valve timing that is adapted to the different engine operating conditions can be achieved with the MAHLE Shifting Roller System. Functionalities can thus be integrated to manage exhaust gas temperature and save fuel or even an engine braking function.

  • Reduction in the total cost of ownership (TCO) of commercial vehicles with MAHLE solutions
  • Promising strategies: waste heat recovery, functional integration in the valve train, and optimized thermal processes

Thanks to an adjustable cam follower, the system can be brought into contact with one of the two cam lobes, which have different profiles. The electrically actuated function has a simple and robust design. Depending on the lift curve of the second cam lobe, the engine can be operated as a permanent brake, for exhaust gas temperature management, or for use with Miller cycles. Compared with adjustable cam segments on the camshaft, the moving masses in the Shifting Roller System are significantly smaller. This results in lower actuating forces and reduced installation space. Many of the advantages of the MAHLE Shifting Roller System are due to its electric actuation. Electrically actuated systems work reliably because they are temperature independent, allow selective cylinder activation, and switch between the operating states quickly and cleanly.

Engine brake: When used as an engine brake, the MAHLE Shifting Roller System achieves a braking effect close to the retarder, even at low speeds, thanks to its two-stroke mode. It also offers a performance advantage in comparison with hydraulically actuated systems. The braking effect of the MAHLE system is at approximately the same level as the engine output. Furthermore, no additional components or systems are required for the engine brake. As the cylinders can be activated individually, the engine brake can be actuated gradually and adapted to the current brake power requirements.

Exhaust gas temperature management: Opening the exhaust valves sooner allows the exhaust gas temperature to be increased while keeping fuel consumption low. Exhaust gas with a higher enthalpy allows earlier SCR catalyst light-off or regeneration of the particulate filter under partial-load operation.

Miller/Atkinson cycle: Closing the intake valves earlier or later allows the effective compression ratio to be reduced, thereby lowering the combustion temperature and pressure. Part of the compression work is thus transferred to the turbocharger.


MAHLE is a leading international development partner and supplier to the automotive industry as well as a pioneer for the mobility of the future. The MAHLE Group is committed to making transportation more efficient, more environmentally friendly, and more comfortable by continuously optimizing the combustion engine, driving forward the use of alternative fuels, and laying the foundation for the worldwide introduction of e-mobility. The group’s product portfolio addresses all the crucial issues relating to the powertrain and air conditioning technology—both for drives with combustion engines and for e-mobility. MAHLE products are fitted in at least every second vehicle worldwide. Components and systems from MAHLE are also used off the road—in stationary applications, for mobile machinery, rail transport, as well as marine applications.

In 2017, the group generated sales of approximately EUR 12.8 billion with about 78,000 employees and is represented in more than 30 countries with 170 production locations. At 16 major research and development centers in Germany, Great Britain, Luxembourg, Spain, Slovenia, the USA, Brazil, Japan, China, and India, around 6,100 development engineers and technicians are working on innovative solutions for the mobility of the future.

For further information, contact:

Christopher Rimmele
Corporate Communications/Public Relations
Pragstraße 26–46
70376 Stuttgart/Germany
Phone: +49 711 501-12374
Fax: +49 711 501-13700