The SACHS dual-mass flywheel for passenger cars:
Vibration Reduction in All Speed Ranges.

Cause:

• Caused by incorrect clutch use, e.g. clutch slip.

Consequence:

• Heat counteracts the effect of the damping grease. Sliding shoes, spring plate and springs run dry.
• The vibration damping function is limited and/or can no longer be guaranteed.
• Heat spots can cause clutch grabbing.

Note:

• Clearly visible annealing discoloration and heat cracking.

Cause:

• Extreme mechanical strain on the entire DMF.

Consequence:

• Destruction of interior components
• In extreme cases, internal components wear through the housing of the primary flywheel.
• This leads to total failure of the DMF.

Note:

• Grease leakage is another sign of this problem.

Cause:

• Thrust bearing wear between primary and secondary flywheel due to mechanical strain.

Consequence:

• The vibration damping function is limited and/or can no longer be guaranteed.

Note:

• Clearly noticeable by the annealing colors, as well as the unusual vehicle noise that gets stronger when disengaging the clutch.

The DMF transmits the engine torque to the clutch pressure plate and the clutch disk. Its primary purpose is to isolate the torsional vibrations generated in the engine, preventing them from passing into the driveline.

The current engine technology places higher and higher demands on clutch systems and the entire driveline. Consumption-optimized truck engines, such as diesel and gasoline engines using direct injection, already develop high torque at low speeds. The usable engine speed range is additionally reduced towards the idling speed level to enable fuel-efficient and low-emission driving. This increases the combustion engine's rotational irregularities. For the driveline and driver, this means increased vibrations, increased noise and reduced comfort. This is where the DMF comes in as a powerful torsional vibration isolator. It helps protect the driveline against harmful vibration and ensures low-noise and comfortable driving.

The SACHS dual-mass flywheel is installed between engine and transmission, together with the clutch pressure plate and the clutch disk.

The flywheel's rotating mass is divided into a primary and a secondary mass. An extremely powerful multi-spring damping system is installed between the two masses.

Effective compression springs with a multi-stage characteristic curve design ensure optimal vibration isolation.

The SACHS DMF offers numerous advantages, such as optimal vibration isolation across the entire speed range, individual adaptation to the vehicle design, effective noise reduction, smooth setting-off behavior, great shifting and driving comfort, protection of the transmission, excellent start-stop behavior, long service life, reduced installation space requirements, possible pull-type and push-type clutch actuation as well as fuel economy thanks to reduced consumption because vehicles can be operated at lower rpm levels.

A DMF can only be tested on a special test bench for dual-mass flywheels. The workshop can only perform a visual inspection. The visual inspection, however, – similar to the tests on the test bench – only provides a snapshot. The assessment of such an inspection requires a great deal of expertise.

Inspect the dual-mass flywheel each time the clutch is replaced. If the clutch has already been replaced once, the dual-mass flywheel should be replaced in any case.