Patent GB-454789-A (GB)
Title: Improvements in or relating to variable speed transmission mechanisms
IPC: F16D45/00
Filed: 1935-01-07
Abstract: 454,789. Change-speed gearing; claw-clutches. CHRYSLER CORPORATION, 341, Massachusetts Avenue, Highland Park, Michigan, U.S.A.-(Assignees of Dunn, W. T.) Jan. 7, 1935, No. 510. Convention date, Jan. 18, 1934. [Class 80 (ii)] An automatic two-speed overdriving unit A, preferably arranged behind the normal three-speed transmission B of a motor - vehicle, provides a direct-drive through a one-way roller clutch D, and a bidirectional planetary or countershaft overdrive through a centrifugal positive clutch C, which engages above a predetermined vehiclespeed, only when its clutching-parts have been synchronized by releasing the vehicle accelerator-pedal to cause overrunning in the one-way clutch. A clutch-dog 36, controlled manually at will and also bv the reverse shifter-rod of the preceding change-speed gear, locks the one-way clutch D, thereby rendering the overdrive ineffective. The centrifugal positive clutch, which forms the subject-matter of Specification 452,767, comprises centrifugal pawls 90 slidable radially in a driven cage 43 to engage clutching-slots 45 in a driving shell 44, the clutch being more fully described below. In the countershaft overdrive shown in Fig. 1, the driving shell 44 is normally clutched by the dog 36 to the driving shaft 25, which shaft constitutes an extension of the driven shaft 23 of the preceding change-speed gear. The driven pawl-cage 43 is integral with a pinion 37, permanently connected, by a countershaft gear-pair 40, with a pinion 42 fast on the final driven shaft 10, which latter is directly and permanently connected to the driving shaft 25 by the one-way clutch D. During direct-drive through the one-way clutch D, the pawl-cage 43 is driven forwardly through the countershaft at a lower speed than the outer slotted shell 44 and after the predetermined vehicle-speed has been exceeded the pawls 90 fly outwards, but do not engage in the slots 45, since they are provided with inclined outer faces 105, which ratchet over the slots. On momentarily releasing the accelerator pedal, the one-way clutch D overruns, and the consequent retardation of the driving shaft 25 relatively to the driven shaft 10 synchronizes the cage and shell, whereupon the pawls 90 engage the clutching slots 45 and introduce the geared overdrive. The pawls 90 have counterbalancing tails 93, which form bearing-faces for one side of the opposing pawl. Springs 94 oppose the outward centrifugal movement of the pawls, and can be adjusted by turning bolts 96, access to which is had through the clutch-slots 45. Adjustable spring- detents 102 lock the bolts 96. The splined clutch-dog 36 can be disengaged from the clutch-shell 44 and engage with the outer member of the one-way clutch D so as to lock the latter, and it also has an intermediate position giving a one-way drive with the overdrive ineffective. The reverse shifter-rod of the preceding change-speed gear moves the clutch-dog 36 to the position for locking the one-way clutch, and a manual button on the dashboard also controls the three positions of the clutch-dog through a Bowden cable, the button having a fourth located position in which it closes a cut-off valve, leading to a vacuum cylinder for actuating the main clutch. Fig. 7 shows a double planetary overdriving unit in which the pawl-assembly 244a of the centrifugal clutch C<1> is integral with the driving member 224a of the one-way clutch D, fast on the driving shaft 221b. The slotted shell 241a of the centrifugal clutch carries planets 240a engaging a loose sun-wheel 239 which acts as a carrier for further planets 238 engaging a permanently fixed reaction annulus 235 and a sun-wheel secured to the driving shaft 221b. The planets 240a also engage an annulus 243a, splined to the driven member 227a of the one-way clutch D, which member is splined to the driven shaft 210a by way of the clutch-dog 232, which is used for locking the roller clutch. Fig. 8 (not shown), uses a single planetary train in which the sunwheel 239, Fig. 7, is permanently fixed, the train 238 being omitted. The Specification as open to inspection under Sect. 91 describes in detail a single steppedplanetary train and also a countershaft gear in which the pinions 37, 38, Fig. 1, are omitted, the countershaft being constituted by an extension of that 21 of the preceding gear, and the centrifugal clutch being arranged behind the final driven pinion 42. Modified dog clutching arrangements are also described. Figs. 7 (Cancelled) and 8 (Cancelled) show a modified centrifugal clutch in which hunting of the pawls 51 is prevented by secondary yielding means comprising spring ball-detents 98, engaging recesses 99 in the tails of the opposite pawls, such means acting to resist outward movement of the pawls and ensure rapid movement thereof. Similar recesses 100 may also be provided to resist inward movement from the clutching position, and also cause the clutch to disengage at a lower speed than that at which it engaged. The movement of the pawls is equalized by a ring 92, pivoted at 94 to each pawl. The gear ratio may provide under-, instead of over-drive. This subjectmatter does not appear in the Specification as accepted.