Patent GB-526660-A (GB)
Title: Improvements in or relating to clutches
IPC: F16D13/71
Filed: 1939-03-24
Abstract: 526,660. Operating friction clutches. BORG-WARNER CORPORATION. March 24, 1939, No. 9297. Convention date, March 28, 1938. [Class 80 (ii)] A friction clutch for motor vehicles is normally engaged by an external spring connected to the clutch pedal 46 and acting, through a ball thrust bearing 34, on the inner ends of radial levers 30 which are pivoted at intermediate points 31 to the pressure plate 16 and which are fulcrummed at their outer ends, the plate 16 being retracted, upon depression of the pedals so as to remove the pressure of the external spring from the levers 30, by internal springs. As shown in Fig. 1, an adjustable external extension spring 50 is connected to the pedal 46, which latter has a one-way connection 60, 61 with a lever 40 which is universally pivoted on the clutch housing 42 and which is forked to engage a control sleeve 36 carrying the bearing 34. The levers 30 are fulcrummed on projecting parts 33 of the cover 8, secured to the driving flywheel 6, and the plate 16 is retracted by tension springs 23, Fig. 3, connected between the plate 16 and the cover 8, the plate 16 being driven from the cover 8 by means of flexible metal plates 17, each of which is connected at its outer edge to the cover 8 and at its inner edge to the plate 16. As shown in Fig. 7, the pedal 46 is journalled on a shaft 141, to which is secured a fork 148 co-operating with the control sleeve 36, Fig. 1, and actuates the shaft 141 through an adjustable screw 146 on one arm of a lever 144 fixed to the shaft. An external compression spring 150 acts between a shoulder 153 on a rod 151, pivoted at 152 to the other arm of the lever 144, and an abutment 154 which is pivoted at 155 and through which the rod 151 slidably extends, and normally maintains the fork 148 in the clutch-engaged position shown. As the pedal is depressed, thereby taking the load of the spring 150 from the fork 148, the pivot 152 moves toward, but does not pass beyond, the plane containing the axes 141 and 155, whereby the effective leverage of the spring diminishes and the physical effort required for disengagement is progressively reduced. This arrangement may be modified by employing a tension instead of a compression spring. In the form shown in Fig. 11, in order to permit the engine to move on its resilient mounting without affecting the clutch, the pedal 46 is connected by a pair of parallel links 171 to a member 172 pivoted at 181 on a rod 182 pivoted at 183 to the housing 42, the member 172 being connected by a rod 174 to a lever 175 corresponding to the lever 40 of Fig. 1) and having pivotally connected thereto a rod 188 which is slidable in an abutment 186 pivoted on the rod 182, while a compression spring 190 is arranged between the abutment 186 and an abutment 191 on the rod 188. The effective leverage of the spring 190 again diminishes as the pedal is depressed for clutch disengagement. The clutch construction may bee modified as shown in Fig. 15, wherein no cover is fitted but brackets 215 are secured to the flywheel 6. Each bracket provides a fulcrum mounting for one of the levers 30 by means of a link 225 which has an aperture pivotally and tiltably engaging over a headed stud 223 secured to the bracket and an aperture receiving the outer notched end of the lever 30. Each lever 30 is pivotally mounted in a slot in a lug 235 on the plate 16 by a pin 242 which projects from one side of the lug, such projection being encircled by a torsion spring 243, one end 244 of which takes against the plate 16 while the other end 245 extends through an aperture in the bracket 215 so as to tend to retract the plate 16. The latter is driven from the flywheel by flexible metal plates 247, the outer edge of each of which is secured to a bracket 215 while the inner end is secured to the corresponding lug 235. Reinforcing plates 255 are secured to the lugs 235 over the plates 247, the plate 16 having also a strengthening flange and buttresses (not shown) on its side face. Alternatively, as shown in Fig. 21, the outer rounded end of each lever 30 is fulcrummed in an aperture formed in a bracket 280 secured to the flywheel, retraction of the plate 16 being effected by bowed springs 289, each having one end engaging a notch 290 in the bracket and the other end engaging the lever at 291, while the plate 16 has pairs of lugs 295 between which the brackets engage so as to drive the plate 16.