V-belt

The V-belt, or drive belt, is part of the drive system. The crankshaft driven by the engine power causes the variator to rotate. The resulting rotation is transmitted by the V-belt to the gearbox and the clutch, which ultimately sets the wheel in motion. This power transmission realized by friction can be equated in a highly simplified form with the gear shift and drive principle of the bicycle. In short: the V-belt transmits energy from where it is generated to where it is needed.

V-belt construction

In contrast to the bicycle chain, V-belts in a variator do not run over gears, but between two conical pulleys, which push the drive belt higher or lower depending on the speed and the centrifugal forces generated by the climbing movement of the variator rollers in the roller tracks. The side angle of the drive belt must also be taken into account, which can be straight or diagonal. For example, a V-belt pulley with a pitch of 28° requires a correspondingly adapted V-belt. Pulley and converter pulley also influence the choice of the correct V-belt. It should also be mentioned here that the entire drive system of a scooter must be coordinated in order to achieve optimum performance on the road. The best possible acceleration can only be achieved if a harmonious interaction of variator including its centrifugal weights, V-belts, rear converter, counterpressure spring and clutch can be achieved.

V-belt types

In addition to standard and reinforced V-belts, Kevlar, aramid fibre and glass fibre reinforced V-belts are also available on the market. All these different types of drive belts develop their optimum performance in coordinated drive systems, depending on the objectives and application requirements. For example, the Kevlar V-belt is more stable and durable than the standard belt, and an aramid fibre V-belt is also a heavy-duty component in the drive system. Both are characterised by enormous resistance to expansion and fatigue and have excellent stability in the high-temperature range.

Why is a matching V-belt important?

Selecting the right V-belt is particularly important for the best possible transmission of drive forces to the rear wheel of the scooter. For example, if the V-belt in the scooter is too narrow and thus lies too low on the variator, the final speed is reduced. However, if the belt is too large and therefore too high, this can lead to possible start-up problems. If the V-belt is too long and cannot build up tension, it will slip, causing the transmission of force from the variator to the rear converter unit to be lost at this moment. For the best possible utilization of the V-belt, it is possible to regulate the drive system by means of "Speed Control pulleys". Of course you will also find them in our assortment.

Why does my V-belt break?

Despite all the care taken with its scooter, the V-belt is a wearing part and will eventually cease to function. The following list counts out some "No- go´s" which place special loads on the V-belt and thus limit its service life:

deflected guide slots in the converter, noticeable by permanent jerking while driving

non-round crankshaft

distorted converter and/or V-belt pulley

poorly ventilated Vario housing, which leads to overheating

Standard clutch bell on tuned motors also leads to overheating

Standard clutch on tuning engines, noticeable by slipping V-belts

overcharging

Incorrect counter-pressure spring in the coupling

installation faults

Wear of Vario sliding elements, coupling, variorolls

Changing V-belts: Video instructions