Patent GB-334894-A (GB)
Title: Improvements in or relating to friction clutches for the transmission of power
IPC: B60K23/02
Filed: 1929-06-10
Abstract: 334,894. Gillett, E. H. J. C. June 10, 1929. Controlling different functions by same handle or lever; hydraulic transmission.-In power-transmission systems, particularly adapted to facilitate gear-changing and allow free-wheeling on motor vehicles, there is provided at each end of a variablespeed gear a clutch or other transmission-interrupting device, one or both of which comprises frictionclutch members normally held disengaged but engageable by a servodevice driven from the prime-mover, the variable-speed gear being isolated from the prime mover and driven shaft, in one direction of rotation at least, when the servo-device is rendered inoperative by the control member. The control member may be actuated by initial movement of the accelerator or like speed control, the usual clutch pedal being omitted. The accelerator pedal 6, Fig. 1, is connected to the throttle 9 and by links 10, 11 to the control-valve stem 13 of the servo-device 4, which comprises an oil pump or pumps 28, Fig. 3, geardriven from the engine 1, and an actuating cylinder 34 containing a spring- pressed ram (not shown). The pump draws oil from the casing 22 of the device through passages 31, 37, a valve 38, Fig. 4, and a passage 29, Fig. 3, and delivers it through a passage 30, valve 32, and branched passage 33 to the cylinder 34 and, normally, back to the casing through the by-pass piston valve 36 and passage 31. When, however, the valve.36 has been closed by the control gear, as shown in Fig. 4, the actuating-ram is raised by a pre- - determined number of pump strokes to its topmost position, wheres it uncovers slots 43 in the cylinder, allowing escape of the oil, and, by a pair of rollers 44 carried on a cross-pin 42 passing through the slots 43, turns cam-levers 45 fixed on a spindle 46, the levers 45 then exerting only side pressure on the rollers 44. In a modification, the ram uncovers a by-pass port leading to the engine lubrication-system, and the valve 36 also is arranged to pass oil to the lubrication system when it is not being delivered to the cylinder 34, the suction side of the pump being connected to the engine sump. The ram and pump may then form separate units. Rotation of the spindle 46 acts through linkage 14, 15, 7 on the engine clutch in the speed-gear and clutch casing 2 and, by extending a spring 16 normally overcoming the clutch springs, puts it into engagement. Link 15 and arm 7 have an adjustable connection 7<x> to vary the number of pump strokes required to engage the clutch. This action occurs just prior to opening the throttle 9 from the idling position, so that the engine can be used as a brake. Simultaneously. linkage 18, 19 releases, a brake-band 58, Fig. 6, from a drum 49 on the driving-member 48 of the one-way tail-clutch in the casing 3. Release of the pedal 6 thus isolates the gear-box and brings the gears to rest. The tail-clutch comprises a contracting coil 51 anchored at 50 to the member 49 and at 55<x> to a ring 55 connected by a oneway friction-roller clutch 56 to a drum 52 secured to a. flange of the driven shaft 53. To transmit reverse drive, a lever 20, Fig. 1, secured to a fork 67, is moved to slide a sleeve 66 and throw dogs 64 thereon, slidable through slots 65 in the flange 53<x>, into engagement with dogs 63 on the member 48. Fig. 9 shows a modified bidirectional tail-clutch comprising expanding and contracting coils 74, 75 adapted to grip a driving-drum 69 and anchored at one end, respectively at 74 and 75<x>, to a driven drum 71 and a drum 72 secured thereto. The other ends of the coils are secured respectively to lugs 76<x> and 77<x> on revoluble sleeves 76, 77, the clutch being engaged by thrusting between the lugs 76<x>, 77<x> a wedge 81 on a slidable sleeve 78, which is directly connected bv a fork 80 and links to the accelerator pedal. Figs. 13 and 14 show a servodevice which is combined with either the engine or the tail friction clutch and functions only during relative rotation between the driving and driven members. Plates 85 are splined at 83 to the driving-member 82, and plates 86 slide on bolts 89 connecting a part 87 to a member 88 secured to the driven shaft 91. A swash-plate 84 on the member 82 actuates spring-pressed pump-plungers 95 carried in a block 94 secured to the member 88, which carries also rams 93<x> bearing against the spring-retracted presser-plate 86<x>. Each plunger 95 draws oil through inlet ports 100, passages 99, 98, 106, 104, and a stationary pipe 127 from an atmospheric-pressure reservoir 117 in the clutch casing 90, and delivers it through a flap delivery-valve 97 and passages 101, 102 to the rams 93<x>. A passage (not shown) connects the annular delivery passage 101 with passages 107, 105 communicating through a stationary pipe 128 with a passage 123 in the casing 90. The pipes 127, 128 connect with an oil-tight sleeve 108. The passage 123 leads both to the cylinder 118 of an adjustably spring-pressed accumulator 119 and, through a rotary by-pass valve 124 and passage 122, to the reservoir 117, pressure being thus gradually applied to the rams 93<x> when the valve is shut. The accelerator pedal is linked both to the valve 124 and a fork 115 controlling a rod 109 with a head 110 which, when moved to the right, coacts with shoulders 111 on the rams 95 to retract them positively from the swash-plate 84. The valve 124 is simultaneously opened to allow the oil in the accumulator and behind the rams to be returned to the reservoir 117 by the springs 120, 92 respectively. Adjustment of the accumulator spring 120 varies the rate of engagement of the clutch. Both clutches may be servo-operated. In any of the modifications, a brake, operated by the servo-device or otherwise, is preferably provided to act on the gear-box elements, as shown in Figs. 1 and 6. The first Provisional Specification described an arrangement in which a clutch of the type shown in Figs. 13 and 14 is used as either the engine or tail clutch, the other clutch being actuated in unison therewith by oil by-passed from the first clutch. The second Provisional Specification describes, in connection with the clutches shown in Figs. 1, 3, 4 and 9, the use of a toggle for relieving the operating- gear of load on full engagement of the engineclutch, which may occur before the ram has completed its stroke, and states that the oil may be supplied by the existing engine lubricating- pump. Specification 324,950 is referred to in the second Provisional Specification.