Patent GB-342824-A (GB)
Title: Improvements in or relating to change speed mechanisms
IPC: F16D23/06
Filed: 1929-11-28
Abstract: 342,824. Variable - speed gearing. GENERAL MOTORS CORPORATION, Detroit, Michigan, U.S.A. Nov. 28, 1929, No. 36463. Convention date, July 17. [Class 80 (ii).] In frictional synchronizing means for a positive clutch in motor vehicle variable-speed gearing, of the type having inclined detent surfaces 90, 99, on the positive and friction clutch elements 61, 85, which are brought into contact on relative axial movement to prevent engagement of the positive elements before synchronism, the movable friction member 85 also has a constant frictional bearing on the other positive element, 29, 59 whereby the detent surfaces are brought into contact by a difference in speed. The motor vehicle speed gear shown is of the type having aligned driving and driven shafts 7, 37 and a parallel layshaft 19 and gives three speeds and reverse, direct drive and the constant mesh second speed being synchro-meshed, low speed and reverse, being brought in by a sliding pinion 51. The operating lever is given a greater leverage for operating the synchro-meshed speeds. Direct drive and second speeds are engaged by a splined positive clutch element 61 having clutch teeth 63, 65 to engage respectively with clutch elements 35 on the driving shaft 7 and an element 64 integral with the second speed pinion 59. Positive element 61 carries three radial lugs 67 on which are formed the inclined detent surfaces 90, Fig. 3, and which pass through shaped detent slots 97 in the friction member comprised by a barrel 85 having coned ends to engage frictionally, coned surfaces 33, 62 on the clutched elements 29, 59. To the ends of the lugs 67 is bolted a grooved ring 69 engaged by an operating fork 73. A constant frictional bearing of the barrel 85 on the elements 29, 59 is provided by the cylindrical bearing surfaces 93, 93<1> which merge into the coned surfaces. This friction bearing causes the inclined surfaces 90 on element 61 to move into the detent parts 99 of the barrel slots 97 as shown in Fig. 3, when the speeds differ so that the engaging pressure is transmitted to the barrel to engage the coned surfaces and synchronize the parts. The lugs then move into the central parts of the slots 97 and permit positive engagement. Clutch element 61 also carries in pairs between the lugs 67, spring detents 103 engaging an annular groove in the barrel so that should the friction drag be insufficient to position the detent surfaces 90, 99, the detents 103 would on axial movement of member 61 lightly engage the cone friction surfaces and effect this positioning. The low speed and reverse pinion 51 is moved by a fork carried on a rail 55 slidable on a fixed rod 57, Fig. 2, and the member 61 is operated through a fork 73 rigid with a second rail 74 slidable on a fixed rod 75. A spring detent 76 may be provided to locate the rail 74 in active and neutral positions. Between the rails is a fixed rod 81 apertured to receive a ball 83 forming an interlock. The rails are operated by a lever 101, the end of which is moved laterally through a notch 109 in the fixed bar to engage, on the one side, a notch in the rail 55. To operate the synchro-meshed speeds on the other side of the bar increased resistance has to be overcome and to provide for this the mechanical advantage is increased by operating rail 74 from a point 115 higher up the lever, the end of the lever being clear of the rail by the provision of a recess 123 shown dotted in Fig. 2.