Patent GB-349492-A (GB)
Title: Improvements in and relating to change gear devices
IPC: F16H61/02
Filed: 1930-02-17
Abstract: 349,492. Variable-speed gearing. BLACKSTOCK, G., 52, Warren Road, Toronto, Canada. Feb. 17, 1930, No. 6320. [Class 80 (ii).] Relates to change-speed gearing of the type in which a change down is effected automatically by the load, and a change up by slowing the driving- shaft, as by throttling the engine upon a vehicle. Figs. 1, 2, 4 and 5 show the invention applied to gearing in which different trains are brought in by sliding a clutch ring 67, Fig. 5. The control is effected by a centrifugal yielding coupling 12, 9, Fig. 2. An arm 12 is secured to the driving shaft 1, Fig. 1, to which is also secured a speedchanging cam drum 86. A disc 9 is secured to a loose sleeve 8 which carries rigidly a gear 35 and a cage 10 upon which a clutch ring 67 slides. The sleeve 8 carries also a loose gear 75 with its ring of internal clutch teeth 68. The driven shaft 2 carries rigidly a gear 52 with its ring of internal teeth 93. A counter-shaft 3 carries fast gears 31, 3‹, and a loose gear 3x meshing with the gears 52, 75, 35, respectively. When the clutch ring 67 is in the position shown in Figs. 1 and 5, the low gear is operative, power passing through the control coupling to sleeve 8, from gear 35 to gear 3x, then through a pawl 37, Fig. 4, to a ratchet wheel 45 fast on the shaft 3 then through the pair 3<1>, 52 to the shaft 2. When the ring 67 is moved to engage a ring 68, drive at middle speed passes through the train 75, 30, 3<1>, 52, the pawl 37 overrunning. When the clutch ring 67 is moved farther to engage a ring 93, the countershaft is cut out and there is a direct clutch drive from the cage 10 to the gear 52. The ring 67 is traversed by a relative turning of a cam drum 86 and cage 10, the ring 67 having internal studs engaging a cam groove in the drum. This relative turning is effected by a turning of the disc 9 relatively to the arm 12. To the arm 12 are pivoted centrifugal links 13, Fig. 2, which carry bowls 14 engaging cam recesses 21 upon the face of the disc 9. The arm 12 may also carry light levers 16 carrying bowls pressed by springs 19 against cam surfaces 29 on the disc 9. The cams 21, 29 are so shaped that the control coupling in effect locks in gear positions, and the whole device is used so that during gear change, when the coupling yields, the load on the gearing is eased. To allow the ring 67 to engage the other clutch rings noiselessly, it carries spring fingers 81, 82, Fig. 5, which slip over the teeth of the ring to be engaged until synchronism has been reached. In order to render the ratchet clutch pawl 37 noiseless, it is provided with a spring arm 37‹, Fig. 4, adapted to engage a fine ratchet 45‹ carried by the ratchet wheel 45. Reversed driving may be effected by interposing idlers between the gears 3<1>, 52. In Figs. 9 and 10 is shown the invention applied to an epicyclic two-speed gear. The arm 12 of the control coupling fast on the driving shaft 1 carries only one pair of centrifugal links 13 which may be acted on also by springs 19. The bowls 14 on links 13 engage cams 125 on the other coupling member 9, which is loose on the shaft 1 and carries a sun gear 209. The planets 198 are carried by the driven shaft 2. The internallytoothed reaction member 196 is prevented from rotating backwards by a pawl 200 adapted to engage a fixed detent wheel 202 and rendered silent by a spring arm 205 engaging a fine detent ring 206. The control coupling is normally locked by the shape of cams 125, but when it yields, it causes rigid cam arms 214 on the member 12 to turn relatively to spring dogs 210 carried by the disc 9. These dogs engage teeth 211 on the ring 196 to effect highspeed solid drive with pawl 200 over-running.: Disengagement of these dogs brings in the epicyclic reduced drive. This automatic two-speed gear may be arranged in series with an ordinary gear-box upon a car, either in front or behind. In the latter case, the detent ring 202 is adapted to be freed for backward running when the reversed drive in the gear box is operative.