Carbon clutch dating




Keith Howard’s Technofile article on carbon/carbon clutches (August issue) implies that Tilton invented the lug drive clutch in the 1980s, “an entirely new method of clutch construction was needed. What Tilton came up with was the finger or lug drive.” But this type of multi-plate clutch construction will be familiar to anyone who has ever stripped down an old motorcycle.

Then called a peg drive, it originally used cork inserts as the friction material, and ran in oil. Indeed, looking at the photograph of a Tilton clutch, the only mechanical difference between it and the clutch on my 1970 Royal Enfield Interceptor is that the Enfield clutch has its projections (pegs) on the plates and its cut-outs on the ‘basket’.

The idea probably dates back to the dawn of motoring a clutch plate with exactly the same peripheral shape is illustrated in Rankin Kennedy’s Book of the Motor Car (1914). So, if Tilton’s patent applies to the lug drive principle, rather than the new friction material, surely it ought to have been rejected on grounds of prior art?

I am,Yours etc,

David Landers, Morpeth, Northumberland