CLUTCHVIAWEB: Clutch Discs

The clutch disc is the clutch’s central connection element.

In combination with the clutch pressure plate, it both separates and links engine and powertrain. It also reduces the speed fluctuations in the gearbox caused by the combustion motor. LuK offers the best solutions for every application, from clutch discs with simple torsion damper through to variants with multi-stage dampers, from rigid clutch discs for use in the dual mass flywheel right through to the displacement correction clutch disc.

The statement that this facing complies with the requirements of environmental protection standard ISO 14001 is misleading. ISO 14001 does not just refer to the ability of a company to implement a system
for the avoidance and proper disposal of waste. Whether a friction facing complies with the environmental protection requirements is regulated by EU directives.

The supposedly special facing is a standard organic friction facing. The statement regarding Kevlar (= aramid) is incorrect! This clutch facing contains no aramid, which means that a higher price is not justified.

On the contrary: Energy tests carried out (e.g. 10,000 cycles at approx. 300 °C) have shown that the wear is almost double that of a conventional original equipment organic friction facing. The average friction value is around 11% lower than a normal organic facing and about 25% lower than a cerametallic facing used in original equipment clutches.

With regards to the reputed product benefits of these clutch discs, the following can also be ascertained:
When using clutch disc hubs with arbitrarily increased surface hardness, it is to be noted that a transmission input shaft with lower hardness wears away more heavily. An unwanted side effect of this is premature
repair of the transmission.

The design of the torsion damper of the clutch disc being examined was not adapted to the properties of the tractor. The result of this is disturbing rattling noises in the transmission. Contrary to the statement, the torsion dampers of the clutch discs being inspected do not contain any stop limiters but – with a few models – only
end pieces. These are supposed to prevent the incorporation of the torsion springs in the spring locking plates. This has no effect on the service life of the springs.

Instructions for fitting LuK clutch discs

When fitting a clutch disc, it is important to ensure that the installation direction is correct.
For this reason, an imprint or engraving can be found next to the hub on most clutch discs.
The installation direction of the clutch disc can then be determined using the markings.
The following table list all possible labels, including their translations:

COTE VOLANT Flywheel Side
FW SIDE Flywheel Side
SCHWUNGRADSEITE Flywheel Side
GB SIDE Gearbox Side
PP Gearbox Side
GETRIEBESEITE Gearbox Side
LATO CAMBIO Gearbox Side
T/M SIDE Gearbox Side
TRANS SIDE Gearbox Side

Example:
If GEARBOX SIDE appears on the clutch disc, this side will be facing the gearbox if the installation direction is correct. If there is no label present, the installation direction of the used clutch disc must be noted.
The installation direction of the new clutch disc can then be reliably determined.

Note:
If the clutch disc is installed in an incorrect direction, this can lead to damage to the clutch system or cause the system to fail!

LuK Clutch disc single segment

Function

The clutch disc is the friction partner of the fl ywheel and clutch pressure plate and as such transfers the engine torque to the transmission input shaft. Friction linings are used to synchronize the engine and gearbox speeds and to transfer the engine torque. The materials used must not only fulfill high technical requirements, i.e. be hard-wearing and provide a constant friction coeffi cient and smooth torque build-up, but also comply with current environmental standards. LuK clutch linings are partly developed and
produced by the company itself and conform to both the technical and legal requirements. Every LuK clutch disc features a lining resilience system that is optimized to the particular application and enables smooth torque build-up when moving away and an ergonomically synchronized pedal force curve. On some applications with higher system requirements a special version with multiple-wave double segments is used instead of the standard version with individual segments. An effective lining resilience system produces an even contact pattern, thereby reducing the running in and sagging under temperature and minimizing changes in the cushion defl ection throughout the disc life.

LuK clutch disc double segment

Modern vehicles use sophisticated spring/damper systems

1 Drive disc

2 Friction lining rivet

3 Friction lining

4 Pressure springs

(idle/low-load damper)

5 Pressure springs

(load damper)

6 Hub fl anges

7 Friction rings

8 Support disc

9 Diaphragm springs

10 Spacer plate

11 Mating disc

12 Damper cage assemblies

(idle/low-load damper)

13 Centering taper

14 Axial spring cushion segment

15 Spring cushion rivet

16 Hub

Clutch disc for the DMF
If a DMF is used to damp torsional vibration in the power train, the clutch disc has either a single-stage damper or, depending on the application, no torsion damper at all. In the latter case, either a rigid disc or a clutch disc with displacement correction is used. Engine and gearbox tolerances, especially on transmission intake shafts with out pilot bearing, result in a displacement between crankshaft and gearbox. In conjunction with rigid clutch discs, this displacement can cause idling noises and increased profi le wearing in critical cases. One remedy to this problem is the displacement correction clutch disc, which enables radial displacement of the hub and thereby prevents potential radial forces in the idling and low load ranges. The effi ciency of the pressure springs in the displacement correction clutch disc is limited to the low load range.

Clutch disc design