Timing belt (camshaft)

The timing chain is a component of the camshaft drive of four-stroke engines. It connects the crankshaft to the / the camshaft (s ).

Use

The camshaft (s ) of four-stroke engines must / have to be driven at half crankshaft speed - otherwise the situation is in driving the cam ring of radial engines. A timing chain (or timing belt ) is required wherever the camshaft (s ) not by other machine components, such as push rods ( NSU Max ) Bevel or spur gear is driven.

History

King waves are usually reserved for the motor sports because of the elaborate production. The roller chain as the timing chain was from about 1910, a standard component in engines. Since the early 1970s, the timing belt is the drive element most commonly used. If a grossly negligent mounted timing belt skip, often caused engine failure, since it can come as a result of time-shifted movement between pistons and valves collide (not with " free runners "). Individual manufacturers hold for traditional reasons for the timing chain fixed. Mercedes -Benz for example, in principle rejects the timing belt and used since the 1950s, only timing chain, front and single-axis and vertical shafts, as at the Porsche boxer engines.

As a control chain are predominantly roller chains, bush chains and formerly also used in aircraft engines and U.S. OHV engines tooth chains.

Function and wear

Timing chains need to run tight. To this end, chain tensioner ( tensioner rails ) are used, the spring-loaded or pressure- oil operations provide the correct voltage and on the free movement of barrel lengths - the swing of the chain in the bending direction ( - called " slack side " ( the strand that transmits the forces is the " tight side " ) prevent " whips ").

The slide rails are wearing parts - after about 150.000 to 300.000 km on this should be replaced. On failure of the clamping mechanism, the chain can skip - in many engines then collide with the pistons with the valves, and severe engine damage will result.

The life of a timing chain is highly dependent on the operating conditions and the maintenance of their tension and guide elements. The highly loaded single roller chains are worn partly after 80,000 to 100,000 km. Duplex chains are more durable and can achieve a service life of more than 500,000 km. The wear of the timing chain can be determined by the automatic change of engine timing within a certain mileage. The timing chain is longer if rollers and chain links wear out. However, the camshaft is rotated by the tightening action in relation to the crankshaft. The angular displacement is dependent on the change in length of the timing chain. Therefore, the motor has a strongly worn timing chain restless, because the charge exchange is offset in time. In a very heavily worn chain, the division no longer complies with the gears. The roles then run on the operation on the teeth and cause besides a louder noise and heavy wear on the gears.