AWKnowledge

A revolution in gearbox design is about to sweep through the automotive industry. John Mortimer reports.

It is no secret that most new continuously variable transmission (CVT) projects have now been cancelled in Europe, while PwC Autofacts Global Automotive Outlook for 2005 (Q4 Release) predicts only 1.2% market share for dual clutch transmissions (DCTs) in 2012.

By contrast automated manual transmissions (AMTs) may soon expand exponentially due to Zeroshift – a seamless, instantaneous means of changing gear ratios without interrupting the torque to the driveline. The technique is significantly cheaper than both CVT and DCT due to the use of conventional manual architecture and a single dry clutch. It offers improvements in cost, fuel economy and emissions.

Because of its enhanced performance Zeroshift allows vehicle manufacturers to downsize their powertrains, allowing, for example, a 1.2-litre engine to enjoy the same performance as a 1.4-litre engine. This is achieved due to the complete removal of the shift time normally associated with a synchromesh manual.

Zeroshift Ltd, based in Milton Keynes, UK, is in talks regarding exclusive licence agreements with several global vehicle manufacturers and tier one suppliers, which could collectively apply the transmission across all vehicle segments, from luxury cars, through sports cars to the front wheel drive segment.

Because of its enhanced performance Zeroshift allows vehicle manufacturers to downsize their powertrains, allowing, for example, a 1.2-litre engine to enjoy the same performance as a 1.4-litre engine.

“There is no segment of the passenger car market where Zeroshift couldn’t take first place,” stated Bill Martin, managing director of Zeroshift Ltd. “With each of the other transmission technologies there are segments where some are better suited than others. But this is not so with Zeroshift – it is ideal for all, from luxury car through to city car.”

Zeroshift Ltd is the design and development company behind the new transmission technology. Charles Matthews, former managing director of Rolls-Royce Motor Cars, and former chief executive of Cosworth Technology, was appointed non-executive chairman in August.

The main focus of Zeroshift’s work has been on development, but the system has now reached the stage where it has been demonstrated to potential customers. With an upper torque limit of over 5,000Nm, the design can also be used in off highway, light and heavy commercial vehicles, buses and coaches, agricultural tractors, forklift trucks, military vehicles, motorcycles, & motor racing. It could also be applied successfully to both hybrid vehicle and electric vehicles.

Zeroshift technology centres on a series of unidirectional dogs or bullets, which are automatically used for up- and downshifting under hydraulic (or pneumatic) pressure. These replace the conventional synchromesh unit to create an AMT, with the appropriate control system. The unidirectional nature of the engagement (two sets, one for each direction) means that during a shift the system is engaged in two ratios at the same time albeit in the same torque direction.

First generation AMTs were introduced in small, high volume cars in 2000 but have not been overly successful because they suffer from poor shift quality and torque interrupt that drivers find unacceptable. Based on a manual transmission, but with an automated clutch and shift operation, the AMT has the attraction that it can be produced in existing manual transmission plants. CVTs and DCTs require bespoke manufacturing facilities.

“With each of the other transmission technologies there are segments where some are better suited than others. But this is not so with Zeroshift – it is ideal for all, from luxury car through to city car.”

Proponents of various transmission types have released figures comparing efficiency with planetary automatics. Zeroshift Ltd uniquely uses the conventional manual/AMT as a benchmark. On a city driving cycle, the Zeroshift AMT is expected to return a 5% improvement in fuel economy over a conventional manual/AMT.

According to Martin, replacing synchronizers in a manual transmission with Zeroshift technology is a particularly attractive solution, offering both space and weight benefits. This is especially so in heavy commercial vehicle transmissions.

Zeroshift has so far developed an automated T5 Tremec transmission and installed this in a 2005 Ford Mustang with a 4.2-litre V6 gasoline engine. The company has an enthusiastic group of investors. The likely awarding of several exclusive (segment only) licensing deals is expected to significantly raise Zeroshift’s profile over the coming months.

With so much happening in the current automotive transmission sector, there is inevitably some confusion among market researchers about the potential future size of the market for various types of transmission. One element looks certain – the conventional manual transmission sector looks set to plateau by 2010 while automatics, whether planetary or AMTs, will increase.
One forecast puts vehicle production in 2010 at nearly 70 million vehicles. Automatics could account for half of these and AMTs another 10%.

REPRODUCED WITH THE PERMISSION OF AW KNOWLEDGE.

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