It should be noted the advantage of a belt drive - smoothness and noiselessness of work. It does not require additional maintenance, such as lubrication, and protects the nodes from overload due to slippage.
The working surface is the side faces, and the force is transmitted due to significant friction (jamming) belt into the pulley groove. Therefore, if you see that the belt is working on the bottom surface, it needs to be replaced - it will soon fail.
Weak belt tension leads to slippage under load. This is often the Cause of poor performance of the generator set. The belt is to blame, but the alternator is to blame. In this case, most often when towing the belt, you can hear "shrieks". The performance of the water pump is deteriorating, which can lead to engine overheating. But the latter happens much less frequently.
Excessive, strong belt tension leads to its rapid wear, increases the force on the water pump shaft bearings and the generator front bearing.
Reference:
Doubling the load on a bearing reduces its service life by 8 times. Therefore, excessive force should not be applied.
Normal tension is characterized by a certain deflection of approximately 8...10 mm when pressed with a finger with a force of 3...4 kg in the middle of the section between the water pump and the generator.
Belt tension is most often adjusted by offsetting the alternator. To do this, loosen the nut and bolts securing the generator to the tension bar and tighten the belt with a lever. It's hard to do it by hand.
If your alternator belt breaks while driving (he often leads and water pump), it will be noticeable on the coolant temperature sensor - the temperature rises, and on the ammeter - it will show the battery discharge (the arrow will deviate to the side "minus"). For such a case, we advise you to carry a spare with you, but it’s better not to bring it to this state: sometimes, when a belt breaks, pieces of the belt fall between the radiator and the fan, which leads to the destruction of the cooling tubes.
In modern cars, not only V-belts are used, but also toothed ones, which are used in synchronous gears on high-pressure fuel pump drives (injection pump) and gas distribution mechanism (timing).
For the correct installation of timing belts in these gears, it is necessary to align the corresponding marks on the toothed pulleys of the crankshaft and camshaft with the corresponding marks on the belt and marks on the covers.
Since a break in the toothed belt during engine operation, as a rule, leads to significant damage to the timing and crank-piston group, it is necessary to replace them in accordance with the recommendations of the manufacturer (after about 80 thousand km).
If we consider a chain transmission for driving a gas distribution mechanism, then there are more disadvantages than advantages.
Advantages: increased strength of the steel chain compared to the belt, which makes it possible to transfer more power. But is it really that much power required for the timing drive? Of course not.
There are a lot of disadvantages: wear of the chain joints, additional loads, the need for lubrication, wear of the sprockets. But the main drawback is the increased noise level.