Patent GB-586910-A (GB)
Title: Improvements in or relating to clutch devices
IPC: F16D48/02
Filed: 1942-04-14
Abstract: 586,910. Centrifugal friction clutches ; controlling change-speed gearing. GRAVINA, M., and HAWADIER, M. April 14, 1942, Nos. 4918 and 4919. Convention dates, April 21, 1941, and Jan. 20, 1942. [Class 80 (ii)] In a centrifugal friction-clutch 33, suitable for a motor-vehicle, of the kind wherein centrifugal clutch-engaging masses 10 are pivoted on a floating spider 7, driven through a manuallycontrolled auxiliary friction clutch 50, which does not transmit load torque and is combined with a friction brake 38, by means of which the masscarrying spider can be arrested at any speed to cause disengagement of the main clutch, frictionreducing means, such as a ball thrust-bearing 19, is interposed between the masses 10 and the clutch-engaging presser-plate 27 on which they act. The auxiliary clutch-brake is of the disc type, operated by electromagnetic, hydraulic or pneumatic means, which may be interconnected with the vehicle change-speed control and also with the accelerator pedal 87, for automatic declutching on release of the accelerator pedal when running in first speed or reverse only, or with an engine-driven centrifugal governor for automatic declutching at low engine-speeds in all ratios. A reversely-acting one-way clutch 101 transmits engine-brake torque. In all the constructions described the main-clutch comprises a driven disc 33, splined on a driven shaft 35 and clutched to a driving drum 1 by outward movement of the centrifugal masses 10, which act on the splined clutch presser-plate 27 through push-rods 13, the ball-thrust bearing 19, a rotatable flanged member, and springs 30. Disengagement of the main clutch when the masses collapse is effected by springs 25, which act on studs 23 to retract the ball thrust-bearing 19, and with it, through headed studs 31, the clutch presser-plate 27. In one construction, Fig. 1 (not shown) spring-loaded ball-detents act on inclined notches in the push-rods 13 to assist the disengaging movement and provide a yielding lock in the disengaged position. The auxiliary clutch-brake comprises a friction-disc 50, splined on a flanged sleeve 48, fast to the masscarrying spider 7, which is journalled and located in the driving drum 1 by a ball-bearing 5. Energization of an electromagnetic winding 42 on the drum 1, through a slip-ring and brush 44, attracts the auxiliary clutch-disc 50, thereby clutching the mass-carrying spider 7 to the driving drum 1 and initiating centrifuagl engagement of the main-clutch 33, providing enginespeed is high enough. Energizing a fixed magnet-winding 38 brakes the auxiliary disc 50 and spider 7 causing collapse of the masses and disengagement of the main-clutch at any speed. In the hydraulic or pneumatic form, Fig. 2 (not shown) the auxiliary clutch-brake' has separate clutch and brake discs spaced by a piston sliding on an extension of the sleeve 48 and operated by fluid-pressure from a gear-pump under selective control of a piston distributing-valve. In the electric control shown in Fig. 3, the circuit for the clutch-brake windings is completed by the engine ignition-switch C, and is controlled selectively by rotary switches 82, 88 actuated respectively by the change-speed selector lever L and the vehicle accelerator-pedal 87, the latter acting through a lost-motion connection 96. The change-speed lever L is shown in the neutral position 01, in which brushes 83 bridge contact segments 84, 40, and supply current direct to the brake-magnet winding 38 to keep the mainclutch 33 disengaged. Movement of the changespeed lever L to the position O<1>4 for selecting either of the starting speeds, e.g., low and reverse, bridges contacts 85, 46<1>, supplying current to a segment 91 on the acceleratorcontrolled switch 88. In this position engagement and disengagement of the main-clutch 33 are automatic on depression and release of the accelerator-pedal 87, which energizes the clutch or brake winding 42, 38 through contacts 93, 92 respectively. Movement of the change-speed lever L to position 04 to select other than starting speeds, changes the supply to a contact 46 which continuously energizes the clutch-winding 42 irrespective of the position of the acceleratorpedal. Actual gear-engagement takes place over a range 02 to 03 before the brush leaves the brake-engaging contact 40 so that the clutch is always disengaged during a change. Detent notches 40' are provided in the contact 40 to define the limit of clutch disengagement whilst a gear is engaged. This provides a "free-wheel" position into which the lever L may be moved to disengage the main-clutch in any speed. In a modification, Fig. 4 (not shown) the switch 88, Fig. 3, is operated by an engine-driven centrifugal governor instead of by the accelerator-pedal, so that the brake-winding is automatically energized to cause clutchdisengagement at low engine-speeds. In this case both operative contacts 46, 46<1> of the change-speed actuated switch are connected together and to the contact 91 of the switch 88 so that low engine-speed always disengages the main-clutch in any speed ratio. In a further modification, Fig. 1 (not shown), the acceleratorpedal control is omitted and the change-speed control-lever L controls the clutch and brakewindings directly, but only one of the contacts 46 is provided, the lever being only operative for clutch-control over the travel O1 to 04. In the hydraulic modification, Fig. 2 (not shown), the piston selector-valve controlling the auxiliary clutch-brake of the main clutch is operated by one end of a lever, which is movable bodily along its pivot-axis to bring its other end into selective engagement with notches in the strikerrods of an associated change-speed gear. The lever is operated by a lever, such as the clutch lever L in Fig. 1, pivotal movement of which first operates the selected gear-striker, whereupon further pivotal movement causes the leverend to leave the striker-rod notch and cause engagement of the main clutch. The Specification as open to inspection under Sect. 91 describes a brake-torque transmitting clutch, for use in position 101, Fig. 3, comprising pawls 112, Fig. 5 (Cancelled) pivoted on the driving drum 1 and spring-pressed on to ratchetteeth on the driven shaft 35 below a predetermined speed, above which centrifugal force lifts the pawls out of engagement with the driven shaft. This subject matter does not appear in the Specification as accepted.