Patent GB-428218-A (GB)
Title: Improvements in or relating to change speed gearing
IPC: F16H61/02
Filed: 1933-11-06
Abstract: 428,218. Variable-speed gearing. ROBOT GEARING, Ltd., 39, New Broad Street, London, and RAILTON, R. A., Brooklands Track, Byfleet, Surrey. Nov. 6, 1933, No. 30847. [Class 80 (ii)] Change-speed gearing adapted to give three forward speeds and reverse and to be controlled in forward running either by pre-selection or automatically, comprises two coaxial primary shafts connected to driven elements of a friction clutch, control means being provided by which in one position both driven elements may be connected to the driving part of the clutch, further movement of the means from said position first disengaging one of said driven elements and thereafter disengaging the engaged driven element and re-engaging the previously disengaged driven element. The primary shafts are geared in different ratios to a countershaft in a cage capable of rotation about the axis of the primary shafts, means being provided to restrain the rotation of the cage in one direction. A flywheel disc 10, Fig. 1, with flange 11 and cover plate 12 forms the driving part of a disc-clutch comprising driving plates 13, 14, 15 and driven plates 19, 20, the latter being secured respectively to coaxial primary gear shofts 23, 24. A number of stepped pins, e.g. three, slidably fitted in the cover plate 12 are actuated by a spider 22, the smaller end of each pin being screwed into the plate 15 which is urged rearwardly by springs 17. A shoulder 21 on flange 11 limits the forward movement of plate 14, and another 161 on pin 16 is adapted to act upon the plate 13. The intermediate driving plate is connected by links 30 to a number, e.g. six, of toggles each comprising a lever 28 pivoted to a lug on the back plate 12, the inner ends of the levers being ball-headed to engage springs 32 bearing at their other ends against ballheaded pins 31 screwed into the boss of the plate 12. The spider 22 is coupled by a bearing 33 to a sleeve 34, the rear end of which has two diametrically opposed axial cams 35, Figs. 1, 13, and each engaging a radial pin 36 fixed to a housing 39. The outer ends of pins 36 engage holes in a yoke 40 journalled on fixed pins 41 and actuated by a lever 43 keyed to a shaft 44. As the spider 22 is moved to and fro the clutch plates are disengaged and re-engaged in a particular sequence. A rotatable cage 57 carries gear clusters such as 62, 64, 66 of which the middle wheel 62 meshes with a pinion 61 on shaft 23; the wheel 64 meshes with a wheel 63 on shaft 24 and the pinion 66 meshes with a wheel 65 on the output shaft 51. The cage 57 is permitted to rotate in the normal direction of rotation of the primary shafts by a freewheel device consisting of an annulus 67, rollers 68 and a cam ring 69 journalled on shaft 24 and provided with clutch teeth 70. A slidable jaw-clutch member 71 has teeth 72 adapted to engage either with the teeth 70 or with teeth 73 on shaft 24. Member 71 actuated by a yoke 74 is splined to a sleeve 76 journalled on shaft 24. The front end of sleeve 76 has two diametrically opposed axial cams 77, Fig. 13, to co-operate with cams 35 on sleeve 34. If automatic control is not desired, the cams may be omitted, and the sleeve 76 fixed. The shaft 44 is connected by an arm 80, Fig. 7, to a servo-motor 81 comprising two metal ends 83, 84, Fig. 8, united by a bellows 85. A vacuum connection 87 communicates with a tube 88 fixed to 84, and a tube 89 fixed to 83 telescopes over tube 88 and is slotted at 90 to register with radial ports 91 in a plug 92 having a restricted bore 93. A strong spring 94 tends to keep the bellows distended. A lever 95, Fig. 7, keyed to shaft 44 is connected through linkage 96-99 to a pedal 100 journalled on shaft 44, the movement of which is limited by a stepped sector 101 keyed to a shaft 102 and having steps a, b, c corresponding respectively with low, second and top gear. The shaft 102 is actuated by a lever 103 through linkage including a spring link 104. The lever 103 is movable over notched arcuate members such as 107 in a casing 105, Fig. 11, and comprises a sleeve 108 slidably mounted over an arm 109 on shaft 110, Figs. 7, 11. A lug 114 on sleeve 108 co-operates with the notches. An arm 116 adapted to be engaged by spring tongue 118, is fixed to a tube 117 connected through a spring link 104', Fig. 7, to shaft 75 of the jawclutch member, the arrangement being such that when lever 103 is in " neutral " notch, the member 71, Figs. 1, 13, is engaged with the free wheel cam ring 69, and when in " reverse " with the shaft 24. Control lever 103 can be moved anywhere between " neutral " and " automatic " without movement of arm 116. When lever 103 is moved to " reverse," arm 116 is moved with it. The lever 103 can be returned to " neutral," the arm 116 striking the bevelled end of tongue 118 and depressing it. The servo-motor is controlled jointly by an automatic pilot valve 121, Fig. 7, and a manually actuated valve 122, Figs. 7, 12, the latter having a piston 134 so connected to control lever 103 that when control is set to " automatic " the piston 134 is in its lowest position, and as the lever is moved to " reverse the piston is raised. The pilot valve 121 comprises a loaded piston 125 and piston valve 127 working in a cylinder 123, connected by pipes 124, 129, 130, 132 respectively to the valve 141, Figs. 7, 12 ; the servo-motor ; the engine induction pipe 131 and the top 135 of the cylinder of the control valve 122. With the engine idling, and lever 103 in neutral, valve 141 is raised by a projection 137<1> on piston 134, the pipes 132, 124 and the servo-motor being all open to atmosphere. Consequently, both driven clutch plates 19, 20 are disengaged. Lever 100 is fully depressed, the step a is under lever 43 and the jaw-clutch member 71 maintains the cage 57 locked to the cam sleeve 76. With pre-selective operation, the lever is moved to " low " position and the piston 134 is lowered. The vacuum in pipe 131 being high the piston 125 is raised and the servo-motor actuated. The spider 22 is actuated to bring driven plate 19 into engagement, after which further rotation of lever 43 is prevented. Upon movement of lever 103 to " second," the lever 100 is slightly depressed and released, shaft 44 is rotated, the toggles 28 snap over and plate 19 is released, plate 20 engaged and drive transmitted through shaft 24. With lever moved to " top," both driven plates are engaged and the gearing is locked solid for direct drive. If " automatic " gearchanging is desired, the lever 103 is moved to " automatic " and this lowers the piston 134 and puts the pipe 132 into communication with the atmosphere, and the space above piston 125 into communication with the induction pipe. With engine unloaded and vacuum high, piston 125 rises, the servo-motor is placed in communication with the induction pipe and slowly contracts, engaging low gear. Torque reaction rocks the cage 57 in a negative direction and thus, through cams 35, 77, urges the spider 22 forward. With relatively high engine torque and vacuum not low enough to allow pilot valve 125 to fall, bottom gear is engaged, but as the torque decreases the cage rotates positively to allow spider 22 to move rearwards and when the torque drops still farther, the toggles snap over and second gear is engaged. Other changes are described depending on variation of vacuum in the induction pipe. Movement of the control lever to " reverse " disengages member 71 from cam ring 69 and engages it with shaft 24. The servo-motor rocks the shaft 44 until lever 43 rests on stop a and the low gear plate 19 is engaged. The gearing now operates as an epicyclic system, the cage and output shaft rotating in a negative direction. Specification 401,070 is referred to.