FIRST consideration is given by the author to basic improvements in clutches of the lever-release single-plate and to those of the two-plate types. He emphasizes that the severity of clutch service has increased very materially in the last few years and that the increased clutch duty of today is further augmented by the car manufacturer in providing cars having greater acceleration and higher torque, particularly at the higher speeds and usually without a proportionate increase in clutch size.
Developments along logical lines which have resulted in improvements in design are cited as being (a) the design of the driven disc and the selection of facings, to produce improved engagement and greater life; (b) design of the cover-plate assembly to permit higher spring pressure with less retracting movement of the pressure plate; and better selection of facing and pressure-plate materials to reduce facing wear and pressure-plate distortion or scoring.
In discussing automatic clutches, comments are made on those of the centrifugal type, on manual operation at all speeds, on conversion of a clutch from an automatic to a conventional type under certain conditions, and on free-wheeling. Manufacturing problems, typical designs of centrifugal clutches, and fluid couplings are treated also.
Clutch control means the control of a conventional type of clutch through an external agency such as the vacuum control, as distinguished from those in which the automatic action of engagement or disengagement is inherent in the design of the clutch proper. The vacuum-controlled clutch is then described and commented upon.