CLUTCHES

How the Clutch System works

The clutch system is one of the most important components of your vehicle, it allows you to place your car equipped with a manual transmission in gear, while at the same time shift to the next gear as your car starts moving.

There are two kinds of clutch systems:

  • Mechanical clutch system
  • Hydraulic clutch system

Most of the newer vehicles are equipped with hydraulic systems due to their self adjusting feature, older mechanical clutches needed constant adjustment to maintain proper clearance between the clutch release bearing and the clutch pressure plate,

clutch disc

When you depress the clutch pedal in your vehicle, it pushes a rod connected to the clutch master cylinder, it is in this part that the mechanical pressure being applied by the dutch pedal is transformed in to hydraulic pressure.

The master cylinder either has a reservoir attached to it, or it is connected to a remote reservoir, this reservoir contains the hydraulic fluid ( most systems use brake fluid), that will be forced through the line in to the clutch slave cylinder.

It is the hydraulic pressure entering the clutch slave cylinder that activates a rod in an external slave cylinder against the clutch fork. The clutch fork will apply pressure against the pressure plate through the clutch release bearing.

In an internal clutch slave cylinder system, the slave and the release bearing are one unit, eliminating the need of a clutch fork.

The pressure being applied by the release bearing forces the pressure plate to decrease the pressure it has against the clutch disc, once this is achieved, the transmission is not longer turning along with the engine, and it is now that you can place the vehicle in gear without damaging the transmission.

The clutch disc is the part that makes contact with both the pressure plate and the flywheel. The splines in the center of the clutch disc allow the disc to slide in the splines of the input shaft of the manual transmission, that is how the rotational movement of the engine is transferred from the flywheel to the transmission.

The flywheel is bolted to the rear of the engine , to the crankshaft to be more specific, the crankshaft is the one that converts the up and down movement of the pistons in to rotational movement, that’s why the flywheel turns when the engine is running.

So, basically, the function of the clutch is to transfer the rotational movement of the engine to the transmission, while at the same time offers a way to disconnect this force at the driver’s command every time the clutch is depressed.

 

 

 

 

 

 

 

Dual Mass Flywheels (DMFs)

Dual mass flywheels (DMFs) are fitted to many diesel vehicles; they eliminate excessive transmission noise, protect the gearbox from damage, reduce gear change effort, and increase fuel economy, as the engine works at a lower rpm.

The DMF acts as a damper between the crankshaft and the input shaft on the gearbox. DMFs are made of two parts connected to a central friction ring that allows slip between them.

DMFs work by having a set of springs inserted between two rotating masses; the slip is cushioned by a set of torsional springs that smooth out irregular torque pulses from the engine. The springs are sized to absorb some of the resonant vibration from the diesel engine under load conditions. These irregular torsional forces can cause excessive transmission noise, difficult gear change operations and increased wear to the drivetrain components.

All DMFs wear out over time. It is recommended the DMF is changed with the clutch.

 

 

 

DMF

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