Belts Instead of Chains

Used in engine systems in place of camshaft timing chains, the CONTI® BELT IN OIL (BIO) synchronizes camshaft and crankshaft. The timing belt has 30 percent less frictional loss than chain drives. This cuts fuel consumption by as much as 0.2 liters per 100 kilometers, resulting in a reduction in CO₂ emissions of 2 grams per kilometer. A study by FEV Motorentechnik GmbH, an engine development service provider, has demonstrated the benefits of using timing belts rather than chain drives.

Since rubber on metal generates less noise than steel on metal, belt-driven drives also have the advantage of being quieter than chain drives. What is more, oval sprocket crankshaft gears make it possible to reduce overall widths by 30 percent compared to conventional toothed belt drives. This negates the original advantages of chains, i.e., narrower widths, and the tensioning rail required for simple chain drives can also be eliminated.

Comparison of systems: timing belt/chain

Properties	Timing belt dry	Timing belt in oil	Sleeve-type chain	Toothed chain
Dynamic strength (engine service life)	++ Series	++	++ Series	++
Noise behavior	+	++	0	+
Precise timing (minimal elongation)	+	+	0	0
Minimal frictional loss	+	++	0	0
Failure warning	-	-	+ Noise	+ Noise
Suitable for diesel engines (soot particle resistance)	++	++	++	-
Suitable for gasoline engines (biofuel resistance)	++	+	++	++
Axial installation space required (width)	0	0	+	+
Layout flexibility	+	+	0	0
Key: – weak; O acceptable; + good; ++ very good

Less frictional loss results in lower CO₂ emissions