Multiple-disc friction clutch and diaphragm spring therefor

A friction clutch, especially a multiple-disc clutch, comprising a pair of axially movable pressure plates;

• a pair of clutch plates flanking said pressure plates;
• and a diaphragm spring disposed between said pressure plates and including a circumferentially extending marginal portion engaging one of said pressure plates and a second portion disposed radially inwardly of said marginal portion, one of said portions engaging the other of said pressure plates radially inwardly of the locus of engagement between said marginal portion and said one pressure plate so that said pressure plates are biased against the respective clutch plates in the engaged condition of the clutch, said second portion including a part disposed radially inwardly of the region of engagement of said one portion with said other pressure plate and comprising a plurality of sections which are connected to each other at locations disposed radially inwardly of said region of engagement, said second portion defining a substantially centrally located opening and further including an annulus of prongs surrounding said opening, said second portion further having open slots alternating with said prongs and closed slots including enlarged outer portions inwardly adjacent to said marginal portion and inner portions extending toward but short of said opening and overlapping the neighboring open slots, as considered in the radial direction of said diaphragm spring, said open slots being located radially inwardly of said enlarged outer portions.