ContiTech Press Releases

Hanover, June 2009Early recognition of typical fault patterns • Damage not always obvious • Failure leads to belt damage

Torsional vibration dampers (TVDs) perform a key function in the drive system of modern diesel engines: They absorb vibrations from the crankshaft. A defective torsional vibration damper means that the torsional vibrations of the crankshaft will damage not only the drive belt but also the driven accessories. This is why engine mechanics should inspect belt pulleys each time the belt is changed. Great care should be taken when inspecting the parts since the damage is not always obvious.
ContiTech provides tips on what fitters should watch out for during vehicle maintenance in order to prevent failure and consequential damage:

Surface hardening with microcracking on the vibration damper is a sign of aging (see Fig. 1). This ultimately leads to TVD failure.

Most torsional vibration damper deterioration initially becomes visible on the rear side of the pulleys. Figure 2 shows marked deformation of the ring of elastomeric material, while the front side is still in good condition (Fig. 3). This damage is often overlooked in inspections because the pulley itself is not removed for visual inspection purposes, and is only examined from the front.

Mechanics should pay special attention to the condition of torsional vibra¬tion dampers in vehicles exhibiting conspicuous noise, stoppages, or un¬natural wear to the V-belt or multiple V-ribbed belt.

ContiTech recommends that the torsional vibration damper be checked for cracking, deformation and signs of corrosion every 60,000 km. Replacement is advisable every 120,000 km. This is because not every case of aging/overload is clearly evident in the form of a fault pattern, although it very much impairs the proper functioning of the engine nonetheless. Workshops are playing it safe whenever they replace the belts and torsional vibration dampers or torsional vibration isolators (TVIs) at the same time, especially since the components are then perfectly matched to each other. ContiTech supplies whole kits of components in original equipment quality, comprising the TVD or TVI as well as the multiple V-ribbed belt. In the case of a TVI, the belt drive of the auxiliary assembly is also isolated to save wear and tear on the belt and the driven assembly.