A typical Clutch Assembly:

The ‘Diaphragm’ type Clutch Assy deployed in most present day cars comprises – I) the Flywheel ‘Face’, ii) the Clutch ‘Disc/Plate’, iii) the ‘Pressure Plate’ and iv) ‘Release’ Bearing. The illustration below should give one an idea as to how they are all ‘lined-up’ inside the ‘Bell-Housing’.

When you depress the Clutch Pedal in the Cabin, a 'cable' linking the pedal to the Clutch Operating Mechanism pushes the Release Bearing forward towards the 'Fingers' of the Pressure Plate Diaphragm - to release the Clutch-Disc otherwise held firmly between the Engine Flywheel at one end and the ‘Pressure-Plate at the other and vice–versa.

The Clutch Disc is mounted on the Gearbox Input Shaft, which is ‘splined’ (the male) and a mating female ‘hub’ at the centre of the Clutch Disc. The sketch above is illustrative of such an arrangement.

Normally, assuming your Clutch is correctly adjusted, which is seldom the case, with your foot completely off the clutch pedal - the Release Bearing is a supposed to be a little distance away from the PP-Fingers and thus not rotating.

The correct adjustment for such Clutches means a ‘Free-Play’ of 2-4 mm ‘at the main operating lever’ on the Bell Housing and NOT on the pedal in cabin. On the otherhand, some European designs follow the opposite practice by deploying suitable long life Release Bearings and Pressure-Plate Fingers. In such arrangements, the release bearing is always in gentle contact with the PP fingers – thus eliminating the 2-4 mm kind of free-play as above and a larger one, annoying at times, at the in-cabin Clutch Pedal.

In such an arrangement, it’s virtually impossible to ‘over-adjust’ the Clutch as talked about above. If at all attempted, it results in the Clutch Pedal within the Cabin rising above the adjoining Brake Pedal level and thus makes it almost immediately apparent - even to a layperson.

Further, since the mechanical effort required to actuate a Clutch is directly proportional to the max Engine Torque and Power it’s designed to transmit without ‘slipping’, higher powered Cars invariably have a ‘hydraulic-assist’ feature to actuate them – quite like the hydraulic brakes (without vacuum servo assist) as deployed in lower powered Cars.