Timing belt. 1.9 TDI PD from VAG Group. Family of diesel engines with injection pump-injector

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10/05/2022
Timing belt. 1.9 TDI PD from VAG Group. Family of diesel engines with injection pump-injector

Timing belt

 

Significant pump effort is required to create a high injection pressure of up to 27,846 pounds per square inch (192,000 kPa / 1920 bar). These efforts deplete the components of the toothed belt drive.

 

There are several modifications to relieve the load on the timing belt:

• Vibration damper built into the camshaft gear, reduces vibration in the drive belt drive;

• The timing belt is approximately 0.20 inches (5 mm) wider than the timing belt used in the base engine. Greater forces can be transmitted over a larger surface area;

• The hydraulic tensioner keeps the timing belt evenly tensioned in different load conditions;

• Some teeth on the crankshaft timing belt have a larger clearance to reduce timing belt wear.

 

 

 

To relieve the load on the timing belt during the injection cycle, the crankshaft timing belt gear has two pairs of teeth with a larger gap than the other teeth.

 

 

 

 

Functions

 

The timing belt is loaded during the injection cycle. The toothed gear of the timing belt is slowed down by pumping forces. At the same time, the combustion process accelerates the belt transmission of the crankshaft. The toothed belt is stretched, resulting in a temporary increase in pitch. Due to the order in which the engine is started, this stretching process occurs at regular intervals, and the same teeth on the timing belt gears are in engagement with the timing belt each time.

 

Uneven gap between teeth

 

On the 1.9-liter TDI engine with pump injection system, the crankshaft timing teeth have a longer gap at certain points to compensate for the change in pitch of the belt tines and thus reduce the wear of the timing belt.

 

 

 

 

Read more about the family of diesel engines with injection pump-injector here .