Patent GB-525309-A (GB)
Title: Improvements in change speed gearing
IPC: F16H63/20
Filed: 1939-02-17
Abstract: 525,309. Change-speed gearing. DAIMLER BENZ AKT.-GES. Feb. 17, 1939, No. 5318. Convention date, Feb. 26, 1938. [Class 80 (ii)] Relates to change-speed gearing in which constant-mesh gears with synchronizing clutches, e.g., 14, 15 for the most frequently used speeds, have a constant exit drive, e.g. the wheels 13, 6, to the driven shaft 3 for. all the indirect speeds, whereby, when the main-clutch is disengaged, all the pairs of constant-mesh wheels are in driving connection with the driven shaft only, whereby the accelerating and retarding load on the synchronizing clutches is kept as small as possible. In such a gear, the driving shaft 2 has a fast wheel 5 which is put into driving engagement with the layshaft 4 solely for low-speed and reverse. Five forward speeds and reverse, including direct-drive and one overdrive, are provided in the arrangement shown, wherein four wheels 6, 7, 8, 9, constantly meshing wheels 13, 10, 11, 12 fast on the countershaft 4, are loosely mounted on an aligned driving shaft 2 and clutched thereto by the double synchronizing clutches 14, 15. The lowest speed and reverse are provided by preliminary sliding-wheel gearing 18 between the driving shaft 2 and either the countershaft 4 or, as shown, the wheel 7 of the third-, or second-speed pairs, the resulting drive being passed to the driven shaft 3 through the third- or second-speed pair 7, 10, the countershaft 4 and the constant return pair 13, 6. The wheel 18 may, as shown, be splined directly on a forward extension of the wheel 7, and be adapted to mesh directly with a wheel 20 on a second countershaft driven by a wheel 5 fast on the driving shaft 2, for low-speed, or to mesh with a reverse idler 25 driven from the second countershaft, for reverse. The second countershaft is arranged at substantially the same level as the driving shaft 2, thereby providing room beneath the shaft 2 for accommodating a transverse member 32 for attaching the transmission to the vehicle frame, so that a lower frame construction results. Alternatively the sliding- wheel 18 may be splined directly to a forward extension of the main countershaft 4, for direct engagement with the wheel 5 or with a reverse idler driven by another wheel fast on the driving shaft 2. As shown in Fig. 1 the three strikerrods 28, 29 &c. controlling the two synchronizing clutches 14, 15 and the sliding wheel 18 are directly operated by a ball-mounted shifter-lever 30 which operates on the forward ends of the shifter-rods so as to clear the floor-space directly over the transmission. This control results in a symmetrical six-position " gate." The modification shown in Figs. 7 to 12 results in the asymmetrical " gate " shown in Fig. 6, reverse, R, and overdrive, V, being on detached legs at each side of a symmetrical four-position " gate " for the first four speeds. For this purpose, the striker-rods 58, 59, act on the clutches 14, 15, through direction-changing levers 67 and the cross-shift movement of the lever 30 selects amongst the three strider-rods 58, 59, 60 by transverse movement of a plate 41, which the lever may engage directly, or, to clear the floor above the transmission, as shown, the lever 30 acts on the plate 41 through an intermediate rockable and slidable member 38. The plate 41 carries a pair of offset projections 44, 45, which, in the four different transverse positions of the plate occupy selective positions, a, a', b, b', c and c<1>, Fig. 9, opposite abutments 52, 53, 54 on different striker-rods 58, 59, 60, whereby the projections 44, 45 selectively move the strikerrods longitudinally to gear-establishing positions when the shifter-lever 30 moves the plate longitudinally through a sliding movement of the interposed member 38. The plate 41 returns an operative striker-rod 59 &c. to neutral by means of one of a pair of loose balls 48, 49 in offset recesses 46, 47 in the plate 41 in line with the corresponding offset projections 44, 45, and operating as follows. In Fig. 12, the projection 45 has just acted on the abutment 53 of the shifter-rod to move the latter to second-speed position. At the same time, an apertured overlying plate 43 has locked the ball 49 in a recess 51 in the abutment 53 of the operative shifterrod 59 whereby the latter is locked to the plate 41 for return movement to neutral therewith. In the neutral position, both balls 48, 49 underlie an opening 61 in the plate 43 and are thereby freed from the recesses 50, 51.