Topics:
Flywheel:
A flywheel ensures that the engine runs more smoothly. A combustion engine delivers power to the crankshaft at the moment ignition takes place in the cylinder; then the crankshaft of the engine is ‘pushed’ a little further forward again. This happens twice every rotation of the crankshaft. The flywheel has a large mass and absorbs part of that energy. The engine will make fewer jerky movements and therefore run more smoothly and evenly. The heavier the flywheel is, the harder it is for the engine to get the flywheel up to speed. Once the flywheel is spinning, it is again more difficult to slow it down. Because of these properties, the shocks released during the power strokes will be reduced.
When the engine has more cylinders (e.g. 8 instead of 4), there are many more exhaust strokes per crankshaft rotation. As a result, the engine already runs more smoothly by itself and a lighter flywheel can be fitted.
The flywheel is mounted at the end of the crankshaft. The clutch is fitted to the flywheel, with the gearbox mounted over it. The starter motor is mounted on the outside of the flywheel.
In racing, a flywheel is often turned down; this means that material is ground off so that it becomes lighter in weight. The advantage is that due to the reduction in weight, the engine will rev up faster because there is less mass to be driven. The disadvantage is that the engine will not idle as smoothly as with an original flywheel.
Dual-mass flywheel:
Nowadays, dual flywheels are increasingly being fitted (also called dual-mass flywheel or two-mass flywheel). The advantage of this flywheel compared to a single flywheel is that it dampens even more small vibrations. It also reduces noises that normally arise from vibrations between the engine and the gearbox.
In a dual flywheel, the total mass of a conventional flywheel is divided into two parts, namely the primary and secondary flywheel. These two parts of the flywheel are mounted together with ball bearings and a damping system with coil springs. The primary part is attached to the crankshaft, the secondary part on the side of the clutch with pressure plate. The driving force is transmitted from the primary part to the secondary part. It is possible to move the secondary part back and forth by about 1 to 2 cm in relation to the primary part. On both sides, the movement is damped by the internally mounted springs. Because this play is possible, the vibrations are damped in this way. The vibrations move in the space where there is play and are damped by the springs. The secondary part therefore responds sluggishly to the direct movements of the primary part.
When the car’s gearbox has been removed, the condition of the flywheel can be checked. The play can be checked by moving the secondary part (where the clutch pressure plate is mounted) back and forth. If this play is too large (more than 2 cm) or noises are audible, there is a high chance that the flywheel is worn. The play has become too great and the vibrations are no longer properly damped. At this point, the function of the dual-mass flywheel may even become counterproductive; the vibrations are amplified.