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Video Engine Management

Video Cylinder Head 1
Video Cylinder Head 2
Video Cylinder Head 3
Video Cylinder Head 4
Video Cylinder Head 5
Video Cylinder Head 6
Video Cylinder Head 7
Video Cylinder Head 8
Video Cylinder Head 9
Video Cylinder Head 10
Video Cylinder Head Repair
Video Cylinder Head Gasket

Video Exchange of Gases
Video Comb. Chamber Shape
Video Cam
Video Camshaft
Video Adjustable Camshaft 1
Video Adjustable Camshaft 2
Video Adjustable Camshaft 3
Video Cambelt
Video Cambelt (assembly)
Video Camshaft Timing Chain
Video Camshaft Timing Chain
Video Upright Shaft
Video Timing Diagram
Video Valves
Video Valve drive
Video Natrium Cooled Valve
Video Valve Spring
Video Valve Stem Guide
Video Valve Seat
Video Valve Seat Angle
Video Valve Stem Sealing
Video Valve Overlap
Video Valve Play Adjustment
Video Valve Contr. (desmo.)
Video Hydraulic Lifter
Video Operating Valves
Video Var. Valve Timing 1
Video Var. Valve Timing 2
Video Var. Valve Lift 1
Video Var. Valve Lift 2
Video Drawrod Engine

Video Engine Control 1
Video Engine Control 2

          A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Toothed-belt Drive (timing belt)

Undemanding, reasonable in price and quite reliable

The timing belt drive can, without special lubrication, low noise crankshaft and, mostly overhead, camshaft(s) be form-fitted at the ratio of 2:1 This form-fit must be maintained throughout it's entire lifespan. If only one tooth is skipped, the least that can happen is that the timing will be changed. In the case of the diesel engine nearly always, in the petrol engine very often, does it cause a destructive contact between the piston(s) and the valve(s).

Nowadays the life of belts is competitive

In the meantime, the producers of drive belts have been put under immense pressure, because both the manufacturers and the buyers want to spare themselves the costly timing belt replacement by choosing the timing chain The further development of the timing belt has led to a lifespan of up to 240.000 km. What remains is the weight saving advantage, because timing belts are not only lighter, they also need neither a sealed area nor guide-rails. In the meantime, even oil-compatible examples are available.

Belts for power transfer, even for the drive-train

On the rear side of the timing belt, other components (e.g., the water pump) can also be force-fittingly driven. It is not only found in the camshaft drive, it's even used in high-torque motorcycle engines (z.B. Harley Davidson) for the secondary drive. The area in which the timing belt works must not, in contrast to the timing chain, be sealed off from the outside world. Quite often a light, plastic covering as protection is sufficient.

Special textile interlining and tooth shapes

The timing belt is made from synthetic material, which, on the drive-side, is strengthened by glas-fibre threads (previously steel wire) and the rear-side by polyamide material. A temperature resistant interlayer provides for good co-operation between the two. In addition, a certain material (e.g., polyamide) is worked into the teeth as well. These teeth can be round-shaped or have other forms, suitable to the respective gear wheels. At least one guide board on either side of the belt pulleys, prevents the timing belt from leaving the wheel over the side, rubbing against the engine housing, thus being worn down narrower and narrower, until, in the end it tears through.

There are measuring instruments for the belt tensioning

When re-using, observe the running direction

Unless otherwise stipulated, tension on the drive side

Slightly oval pulley-wheels -> variable tensile strain

Turbo-engines -> stronger valve springs -> strain on the belt

Diesel engines with pump jets -> tensile strain on the belt

Tooth belt replacement always together with the tension roller               Top of page               Index
2001-2015 Copyright programs, texts, animations, pictures: H. Huppertz - E-Mail
Translator: Don Leslie - Email:

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