How reliable is a dual-mass flywheel?

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42

The flywheel, without any exaggeration, can be called the most versatile device. It not only compensates for uneven rotation of the crankshaft and transmits torque from the engine to the gearbox, but also spins the crankshaft during the start process. Torque pulsations are smoothed out due to periodic short-term accumulation and subsequent release of kinetic energy. The energy reserve occurs during the stroke of the piston, and the consumption occurs in other cycles. At the same time, the more cylinders (and, consequently, the greater the total stroke time), the more uniform the torque of this engine, which means that the mass of the flywheel can be less.

There are several types of flywheels according to their design. The most common - solid - is a massive cast-iron disc with a diameter of 30-40 mm with a steel gear rim pressed on its outer side, which ensures that the crankshaft is rotated during start-up with the help of a starter. There is also a dual-mass flywheel and a lightweight one. The use of a dual-mass flywheel, includingtwo discs included, made it possible to get rid of the installation of a damping device in the clutch disc. A lightweight flywheel is usually used when tuning an engine. The decrease in the moment of inertia occurs due to the displacement of the main mass of the flywheel closer to the edges of the disk, as a result of which its mass is reduced (up to 1.5 kg), dynamic characteristics are improved, and engine power is also increased (up to 5%).

How does a dual-mass flywheel work?

This flywheel consists of not one but two housings. The first of them connects directly to the crankshaft and is also the crown of the starter. The second body is the basis for mounting the clutch assembly. Both housings are interconnected by means of plain bearings (radial and thrust), which have an intermediate damping system. The connection device allows them to move relative to each other in the axial direction. The inside of the dual-mass flywheel is filled with grease to ensure efficient and correct operation of the spring packs. The packages, in turn, are separated by special plastic separators that prevent them from blocking.

The dual-mass flywheel works on a stepped principle. The soft springs of the first stage are responsible for starting and shutting down the engine. Stiffer second stage springs provide torsional damping during normal driving.

This design is made to more reliably dampen vibration, reduce noise, reduce wear of synchronizers, protect the engine transmissionfrom overloads, ease of gear shifting. At the same time, increased wear of the spring-damper system occurs, usually ending in a breakdown of the arc spring, the main element of the dual-mass flywheel.

When should the dual-mass flywheel be replaced?

Uneven engine operation, vibration and noise at idle can cause abnormal operation of the ignition system, plunger pairs, throttle valve, as well as other devices and assemblies, including a sign that the dual-mass flywheel is faulty. Symptoms that clearly indicate that it is time to replace it are as follows:

• formation of cracks on the surface;
• loss of lubricant in clutch housing;
• can't turn it in either direction.

Repair of a dual-mass flywheel in artisanal conditions is almost impossible, and therefore it is usually changed entirely.

Although, in some cases, overhauling and rebuilding a flywheel can be cheaper than buying a new one (minimum cost is around $500). Another option could be to replace it with a regular all-metal one - an analogue of a two-mass one.

According to experts, for a longer and more reliable operation of a dual-mass flywheel, it is necessary to follow the elementary rules of operation, namely: for diesel engines designed to work with high torques, avoid prolonged operation at low speeds, and also depress the clutch pedal before turning off the engine.