Patent GB-711212-A (GB)
Title: Automatically operating change speed gear
IPC: F16H61/02
Filed: 1950-09-14
Abstract: 711,212. Variable-speed gearing; clutches. KKEIS. F. and S.I.B.A. SOC. ITALIANA BBEVETTI AUTOMOBILISTICI AR.L. Sept. 14, 1950 [March 3; 1950]. No. 22614/50. Class 80 (2) In a variable-speed gear, particularly for motor vehicles, employing centrifugal clutches and overrunning freewheels and comprising three automatically-engaged forward speeds and a manual reverse, the driver may, by throttle control, hasten the automatic changes, and the 'gear also includes a device which locks the gearing should the vehicle attempt to run backwards, manual means being provided for disengaging this device when required and for locking one of the freewheels to allow engine braking. The engine flywheel 1 is connected to a hollow shaft 12 and gear 13 by a double-acting centrifugal clutch which engages at a higher speed than it disengages. This clutch comprises a drum 2 which is secured to the flywheel and carries weights 3 which move outwardly against tie springs to engage a drum 7 rotatable with the shaft 12. Thereupon weights 8 carried by the drum 7 and responsive to a lower speed than the weights 3' move outwardly against a tie spring and engage the drum 2. If the engine speed drops, the. weights 8 maintain clutch engagement after the weights 3 disengage. A countershaft 16 has a pinion 17 on which is slidable a sleeve 20 which for forward motion is moved to the right to couple gear 21 to the countershaft. In first gear, drive is effected from drum 7 through gears 13, 14 and freewheel 15 to countershaft 16 and through gears 21, 22 and freewheel 23 to the driven shaft 24. A gear 28 on the countershaft drives a gear 29 connected to a clutch carrier 30. supporting weights 31 which, as the countershaft speed rises, move outwardly against tie springs and through spring-loaded balls, axially separate pressure plates 34 and thereby clutch gear 29 to the drum 7. The shaft 24 is now driven from the drum 7 through second gear comprising clutch 34, gears 29, 28, 21, 22 and freewheel 23, the freewheel 15 overrunning. A clutch carrier 38 is secured to a shaft 37 which is normally connected to the driven shaft 24 through a ball coupling 45, and third gear is engaged when the weights 31a move outwardly and separate corresponding pressure plates to connect shaft 37, and thus shaft 24. directly to the flywheel 1, freewheels 15 and 23 then overrunning. In order that the engagement of clutches 34 or 38 may be hastened to some extent by throttle control the weights 31, 31a are notched and their outward movement is resisted not only by their tie springs but also by axially-movable discs which engage the notches and are controlled by notched centrifugal weights 39, carried by the drum 7. If therefore, the throttle 'is released while the vehicle is accelerating, the vehicle will overrun the engine and the weights 39 will slow down to allow earlier engagement of clutches 34 or 38 than under wholly automatic conditions. A freewheel 13<SP>1</SP> between gear 13 and shaft 37 prevents backward rotation of shaft 24, and hence back-running of the vehicle, . since the gear 13 would then be connected to shaft 24 both directly and through a gear train. To atlow backrunning a three-position sleeve 46 controlling the balls 45 is moved halfway to the right, whereupon the balls move outwardly and break the coupling between shafts 24, 37. The sleeve 46 has dogs engageable with dogs on the gear 22, so that when moved to the extreme right the sleeve 46 locks the freewheel 23 and the vehicle becomes subject to engine braking. To provide a reverse gear, the countershaft pinion 17 continuously engages a pinion on a secondary shaft (not shown) on which is slidable a gear which may be moved into engagement with a gear 27 fixed to the shaft 24, reverse being therefore, engaged by moving sleeve 46 and the said slidable gear to the extremely right, and moving sleeve 20 to the left position shown in the drawing. In a modification. multiple disc clutches replace the clutches 34, 38, each clutch comprising radially slidable main centrifugal weights 57. Fig. 3, carried by a disc 54 which is connected to the driven shaft 56 and has toothed engagement with a body 51 supporting one set of clutch discs. The other set are supported by a disc 53 on the engine shaft 60. Throttle-controlled centrifugal weight rollers 64 are carried by shackles pivoted at 62 to the disc 53, and are bevelled to co-act with a bevelled surface on the clutch back 67. which latter is secured to the body 51, and thereby resist clutch engagement in similar manner to the weights 39 of the clutch 34.