Patent GB-624375-A (GB)
Title: An improved automatic transmission gear box
IPC: F16H61/02
Filed: 1946-10-08
Abstract: 624,375. Variable-speed gearing. KIRKPATRICK, H. G. Oct. 8, 1946, No. 30053. Convention date, Nov. 13, 1945. [Class 80 (ii)] A four-speed change-speed gear comprises primary and secondary drive shafts adapted to be connected to the input shaft through automatic clutches, a lay shaft 33, an output shaft 26 and a manually operable clutch 27. Engine crankshaft 10 has secured thereto a flywheel 11 having a flange 13 which carries pins 14B of shoes 14 of the primary clutch which may engage the flange 17 of a plate 18 bolted to a hub member 19 having a gear wheel 20 formed thereon. Gear wheel 31 mounted on layshaft 33 and connected thereto by a one way roller clutch 32 meshes gear wheel 20. Secondary input shaft 22 carries secondary clutch shoes 69 which at a predetermined speed engage the inner periphery of flange 13 of the flywheel 11. Gear wheel 23 meshes gear wheel 34 which is splined to layshaft 33. Gear wheel 37 is rotatably mounted on layshaft 33 and may be clutched thereto by engagement of the teeth 38 with a member 35 slidably mounted on the layshaft 33. Mounted on the driven shaft 26 and clutched thereto by means of a one way roller clutch 28 is a gear wheel 29 in constant mesh with gear wheel 37. Secondary input shaft 22 and driven shaft 26 may be connected by manual operation of tooth clutch 27 which is slidingly mounted on shaft 26, the drive either passing through one way roller clutch 25 or clutch teeth 24 if it is desired to prevent free-wheeling. A reverse layshaft 39, Fig. 4, has secured thereto gear wheels 40, 59 which transmit the drive from layshaft 33 via gear wheel 36 to gear wheel 29 which for reverse drive is clutched to the output shaft 26 by clutch member 27. The primary centrifugal clutch comprises shoes 14 mounted on pins 14B slidingly extending in apertures in the drum 13 and connected together by springs 15. The secondary centrifugal clutch comprises a hub 65 splined to shaft 22 provided with radial driving pins 66 each of which has a sleeve 67 slidable thereon, the inner end of which supports a weight 68, the other end being attached to a clutch shoe 69. Springs 75 housed in sockets 74 in each weight 68 engage at their outer ends with the shoes 69. Balls 72, 73 housed in the weights 68 engage spring steel corrugated diaphragms 76, 77 which are secured to the hub 65. Rotation of hub 65 causes outward movement of the weights 68 until balls 72, 73 engage the inclined faces 78, 79 of diaphragms 76, 77. At a predetermined speed the centrifugal force is sufficient to overcome the effect of the inclines 78, 79 and the weights 68 move outwardly thereby flexing diaphragms 76, 77. When the balls pass the crest of the inclines 78, 79 surfaces 80, 81 act on the balls assisting the centrifugal action of compression springs 75. A passage system is provided for lubrication of the sliding surfaces of the weights 68 and sleeves 67. The roller clutch 60 comprises a hub 60 splined to shaft 26, provided with inclined flats 60A. Rollers 61 mounted in a cage 62 engage the inner periphery of drum 64 which is integral with gear wheel 29. Wire springs 63 are connected to hub 60 and cage 62 so that they urge the cage in a clockwise direction, Fig. 2. Rotation of gear wheel 29 in a clockwise direction causes rollers 61 to become wedged and effect the drive to hub 60. Anticlockwise rotation of gear wheel 60 causes disengagement of the rollers. Clutches 25, 32 are of similar construction. In operation, with manually operable members in the positions shown in Fig. 1, rotation of crank shaft 10 at a predetermined speed causes engagement of primary clutch 15 and fourth gear is effected through gear wheels 20, 31, clutch 32, shaft 33 member 35 gear wheels 37, 29 and clutch 28 to driven shaft 26. On increase of speed, the secondary clutch becomes engaged and third gear is effected through gear wheels 23, 34, 37, 29. Clutch 32 allows shaft 33 to over-run gear wheel 31. Second gear is effected by manual movement of clutch 27 so that the drive then passes through the primary clutch, gear wheels 20, 31, 34, 23 and through clutches 25, 27 or 24, 27 to the output shaft 26. Increase in speed of driving shaft 10 causes engagement of the secondary centrifugal clutch and the drive is transmitted from shaft 22 to shaft 26 through roller clutch 25 and member 27 or through dog clutch 24 and member 27 if a freewheel drive is not required.