The advantage of the timing belt in oil is that it has a narrower construction than the dry-running version and is even quieter

Less friction + less weight = less fuel consumption - and so fewer CO2 emissions. This simple formula is a dominant theme today in the development departments of automotive manufacturers and their suppliers. It has long ceased being all about grand savings and has instead become a matter of highly detailed work, since every saved gram of CO2 counts in the final analysis.

This is one of the reasons why the timing belt in the timing assembly has gained significantly in importance once again in recent years. Volkswagen is again fitting belts instead of chains in the Golf VII and Audi A1.

And other manufacturers too are increasingly designing their new engines for high-tech drive belts made from rubber and plastic, because they know that belts have distinct advantages over chains in reducing fuel consumption and CO2 emissions from combustion engines.

Studies also confirm this: According to FEV GmbH, an independent engine designer, the belt drive lowers fuel consumption compared to the chain, and therefore reduces CO2 emissions.

In a 1.6 liter gasoline engine, for example, the belt drive reduces fuel consumption by more than 1 per cent and saves up to 1.5 grams of CO2 per kilometer. "Belt drives are lighter and run a lot more quietly too. Belts don't tend to lengthen either," says Hermann Schulte, head of Timing Belt Development at the ContiTech Power Transmission Group.

"A significant advantage, because a lengthening chain alters the engine timing. As a result, consumption increases and performance drops. Emissions levels are quickly exceeded." In endurance tests, a belt lengthened by just 0.1 per cent after 240,000 kilometers of service life - the figure was five times greater with a chain.

Many large automotive manufacturers in Europe are now making use of the benefits of timing belts in their engines and this number is growing. ContiTech supplies dry-running timing belts to manufacturers including Audi, Volkswagen, Volvo, Ford, Opel, and PSA. It's not only camshafts that are controlled by timing belts, but injection systems and oil pumps too.

ContiTech developers are already considering whether to use a timing belt to drive balance shafts as well and therefore make spur gears superfluous. And their focus is on unconventional yet safe solutions, such as the timing-belt-in-oil system.

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