221 Axial driven plate friction lining cushioning

In its simplest form the driven plate consists of a central splined hub. Mounted on this hub is a thin steel disc which in turn supports, by means of a ring of rivets, both halves of the annular friction linings (Figs 2.2 and 2.3).

Axial cushioning between the friction lining faces may be achieved by forming a series of evenly spaced 'T' slots around the outer rim of the disc. This then divides the rim into a number of segments (Arcuate) (Fig. 2.4(a)). A horseshoe shape is further punched out of each segment. The central portion or blade of each horseshoe is given a permanent set to one side and consecutive segments have opposite sets so that every second segment is riveted to the same friction lining. The alternative set of these central blades formed by the horseshoe punch-out spreads the two half friction linings apart.

An improved version uses separately attached, very thin spring steel segments (borglite) (Fig. 2.4(b)), positioned end-on around a slightly thicker disc plate. These segments are provided with a wavy 'set' so as to distance the two half annular friction linings.

Both forms of crimped spring steel segments situated between the friction linings provide

Civil Calculation Formula Pdf
Fig. 2.2 Clutch driven centre plate (pictorial view)

Fig. 2.3 Clutch driven centre plate (sectional view)

Fig. 2.4(a and b) Driven plate cushion take-up

Fig. 2.3 Clutch driven centre plate (sectional view)

Fig. 2.4(a and b) Driven plate cushion take-up progressive take-up over a greater pedal travel and prevent snatch. The separately attached spring segments are thinner than the segments formed out of the single piece driven plate, so that the squeeze take-up is generally softer and the spin inertia of the thinner segments is noticeably reduced.

A further benefit created by the spring segments ensures satisfactory bedding of the facing material and a more even distribution of the work load. In addition, cooling between the friction linings occurs when the clutch is disengaged which helps to stabilise the frictional properties of the face material.

The advantages of axial cushioning of the face linings provide the following:

a) Better clutch engagement control, allowing lower engine speeds to be used at take-up thus prolonging the life of the friction faces.

b) Improved distribution of the friction work over the lining faces reduces peak operating temperatures and prevents lining fade, with the resulting reduction in coefficient of friction and subsequent clutch slip.

The spring take-up characteristics of the driven plate are such that when the clutch is initially engaged, the segments are progressively flattened so that the rate of increase in clamping load is provided by the rate of reaction offered by the spring segments (Fig. 2.5). This first low rate take-up period is followed by a second high rate engagement, caused by the effects of the pressure plate springs exerting their clamping thrust as they are allowed to expand against the pressure plate and so sandwich the friction lining between the flywheel and pressure plate faces.

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