FLYWHEEL
THE DUAL-MASS FLYWHEEL has successfully reduced the vibration that an engine will normally transmit through into the gearbox and drivetrain. A dual mass flywheel is basically constructed from two discs or flywheels roughly the same diameter as a standard run of the mill single plenum flywheel would be. Each disc of the dual mass flywheel would share about one half the mass of a single flywheel. The first flywheel is attached to the crankshaft and with the spigot shaft driving through the second flywheel oscillating in harmony in respect to each other.
An engine and its flywheel that is harmonically balanced still gives off vibrations in a number of different ways. These vibrationms are caused by the combustion forces acting on the pistons and connecting rods, whether it is a two-cycle engine or four-cycle engine. The foremost vibration given off is known as 'torsional vibration transverse' and the effect it has on engine and gearboxes is far worse at lower engine RPM than at mid and high engine speeds. Diesel engine vibrations can be up to five times more severe under operating conditions than that of most petrol driven engines and this is why harmonic balancing plays such an important role in any rotating engine part, with special attention being paid to the flywheel..
Movement is controlled by circumferential springs working against stops or buffers so that the first flywheel is able to vibrate with the crankshaft while the springs ensure that very little of this vibration gets transferred through to the second flywheel. A normal clutch unit, but without springs in the hub of the driven plate, is bolted to the second flywheel and the gearbox input shaft is splined to the driven plate of this clutch. The result is that very little torsional vibration gets transmitted to the rest of the vehicles drivetrain thus ensuring a more harmonious transfer of vibrations as the per the old saying, ‘two is better than one’, which is key to vibration dampening.
The amount of oscillation that takes place is directly related to engine speed and the load bearing capacity of the vehicle. This means that when you combine a large throttle opening with a low engine speed the oscillation will be severe, but as the engine speed climbs, or the throttle opening is reduced, the oscillation will die down. In other words when driving try and refrain from harsh throttle openings and heavy clutching as the modern dual mass flywheel can not take aggressive clutching as the older more conventional clutch and flywheel combinations.
Repairs for a dual mass flywheel in particular can be extremely expensive. For example, a Mercedes-Benz Vito clutch repair costs in the region of R15000.00. An alternative and much cheaper repair method is to replace the unit with a single disc flywheel and clutch assembly at half the price.
This conversion process is being done in South Africa in a number of cases where the flywheel is far too expensive or unavailable from the agents or scrapyards.
For more information CLICK HERE “Flywheels / Adaptor Conversions / Parts” or Call Centre : 0861 7777 22
