Saving Energy the Smart Way

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An energy saving innovation jointly developed by WABCO and ZF for commercial vehicles’ air compressors has been reducing trucks’ fuel consumption and cutting their running costs since 2011.

Andreas Neemann, July 27, 2020

Andreas Neemann wrote his first ZF text in 2001 about 6HP transmissions. Since then, the automotive writer has filled many publications for internal and external readers, showcasing his passion for the Group's more complex subjects.

Long before WABCO was actually acquired by ZF, it was clear that the two companies were very complementary and could form a near “perfect match” if they were to merge. For decades, commercial-vehicle customers have benefited from ZF solutions with “WABCO Inside” or alternatively WABCO solutions with “ZF Inside”. The CDC adaptive damping and the CALM cabin damping systems are good illustrations of these successful collaborations. Thus in 2011, it was WABCO that brought an air compressor with integrated clutch to market – with development partner ZF taking a back seat.

Thus in 2011, it was WABCO that brought an air compressor with integrated clutch to market – with development partner ZF taking a back seat.

The story goes as follows: Commercial vehicles need compressed air, because only pneumatic systems can exert the enormous forces required for braking, air suspension, or shifting clutches and engaging gears. The compressed air is generated by a compressor driven by the truck’s combustion engine. These compressors used to run permanently, even when no compressed air was needed. “We looked for ways to reduce this wasted energy,” says Frank van Son, today Head of Marketing for Division W’s Vehicle Energy Management Systems (VEMS) Business Hub. “If you can temporarily disengage the compressor from the engine and only re-engaging it when it’s needed, you can save up to half a liter of fuel per 100 kilometers,” explains van Son.

A big reduction in fuel consumption

While this may not sound like much, it soon mounts up in everyday operation. A logistics company with ten trucks for instance, each covering 100,000 kilometers (60,000 miles) per year, could expect an annual saving of as much as 5,000 liters of diesel. “Technically, this can be done by decoupling the engine from the compressor when enough compressed air is available on the vehicle,” explains Peter Prystupa, Head of Development Commercial Vehicle Drive Components at ZF in Schweinfurt. So WABCO searched for a development partner capable of designing a pneumatically controlled compressor clutch (known as an air compressor clutch, or ACC for short) – and found one in ZF. “After WABCO’s initial inquiry, the ZF team modified our diaphragm spring/actuating technologies to meet the requirements of an ACC,” explains Prystupa. As part of the development, there were lively exchanges and visits to the locations in Hanover, Wroclaw (WABCO) and Schweinfurt (ZF) and this led to the design of WABCO’s c-comp.

The energy saving innovation jointly developed by WABCO and ZF is reducing fuel consumption of commercial vehicles.

The next generation is in place

Once series production started in 2011, the solution quickly established itself on the market. Major commercial vehicle OEMs trust in the jointly developed technology and offer it in their vehicle ranges.

Both companies have also designed a second, improved generation of air compressor with integrated ACC. Kinga Obrocka, Product Line Leader Air Compressors, describes the specifications: “As an evolutionary upgrade of the original c-comp, the new solution will feature better performance and has already been selected by a major commercial vehicle OEM for its coming range of heavy and medium duty engine platform.”