Patent GB-881658-A (GB)
Title: Improvements in and relating to clutches
IPC: F16D43/09
Filed: 1958-02-04
Abstract: 881,658. Controlling friction clutches. FRANCAISE DU FERODO S.A. Feb. 4, 1958 [Feb. 4, 1957; Jan 7, 1958], No. 3680/58. Class 80 (2). [Also in Groups XXV and XXXIV] In a centrifugal clutch of the kind in which centrifugal masses 33 pivot radially to apply axial clutchengaging pressure to a presser plate 13 through a cam plate 32, thrust bearing 42, transfer plate 31 and springs 39, and the masses 33 pivot on a freely mounted carrier 52, adapted to be frictionally clutched by helical springs 62 to a rotating input casing 27 or braked by a stationary electromagnet 58 for clutch engagement and disengagement respectively, radial outward movement of the masses 33 is limited by a rubber-lined shoulder 48 on the cam 32 itself. A rubber cushion 47 also silences the inward collapse of the masses. The mass-carrier 52 supports on radial bladesprings 55, an armature 57 forming the friction clutch and brake member for the carrier. In the clutching direction for engaging the rotating input casing 27, the magnet armature 57 carries friction segments 59 alternating with the blade springs 55 and contacting the casing 27 only over a radially inner zone 60. The masses 33 are housed in an enclosure rendered oil-tight from the remainder of the clutch by bearing seals 77 and by a cork cone 70 engaged by a casing port 73 attached to the axially slidable transfer plate 31. In Figs. 4 and 7, the electromagnet 97 is axially adjusted to set the air gap by three screws 103 passing through the fixed casing 85 and each accompanied by a further screw 107 abutting a recess in the magnet 97 the whole constituting locking means completed by spring clips 110. In the main clutch the clutch engaging springs 39 are protected from the heat of the presser plate 13 by washers 40 which may be corrugated. A negative-torque ratchetclutch for engine-compression park and push start is arranged between the driven disc 15 and input flywheel 12 and comprises centrifugal pawls 18 pivoted on the flywheel engaging a ratchet-wheel 16 in the driven disc 15, the pawls disengaging centrifugally above a predetermined engine speed. Masks 21 pivoted in the driven disc 15 cover the ratchet teeth to prevent re-engagement if the engine stalls above a predetermined vehicle speed. In Figs. 4 and 9 (not shown), overrun torque is limited by an expanding friction shoe coupling between the driven clutch disc 15 and its hub, and comprising hollow cast-iron shoes 87 which, in the forward direction self-tighten on a driving cam 91 whilst in the overrun direction springs 90 alone supply a limited engaging force. Two rings of cork 121 are provided on the electromagnet 97 which prevent noise on engagement by both the elastic action of the rings and by dash-pot effect which they produce. The friction facing 59 on the armature 57 may be agglomerated cork, the elasticity of which is between 0.025 and 0.075 kg. per sq. cm. and the coefficient of friction is between 0.60 and 0.70, or may be of the usual friction material mounted on an elastic underlay of rubber or agglomerated cork. The electromagnet 97 carries two terminals 112, 113 (Fig. 5) which are connected to the ends of the coil 58. The terminal 112 is supplied from the battery through an ignition switch 116 whilst the other 113 is connected to earth through a touch sensitive switch 117 on the gear-shift lever. A condenser 119 and a high resistance 120 are provided to protect the contacts. Specifications 845,197 and 881,659 are referred to. Reference has been directed by the Comptroller to Specification 586,910.