Patent GB-455699-A (GB)
Title: Improvements relating to change speed mechanisms particularly for motor vehicles
IPC: F16D23/04
Filed: 1935-01-18
Abstract: 455,699. Change-speed gearing. VAUXHALL MOTORS, Ltd., Kimpton Road, Luton, Bedfordshire. Jan. 18, 1935, No. 1710. Void [Abridged as open to inspection under Sect. 91 of the Acts, July 19, 1935]. [Class 80 (ii)] Consists in change-speed mechanism of the compound type comprising a first change-speed mechanism of orthodox type, and a synchromesh change-speed mechanism in series therewith, having means operable when a change is being effected in the first mechanism to brake rotatable elements therein, the control being such that gear changes in the first mechanism cannot be effected unless the second mechanism is in neutral. The gearing shown in Figs. 1 and 2, and which includes a reverse, is of the kind described in Specification 403,422, the first mechanism being of the two-speed type. The input shaft 1 has a pinion 2 engaging a wheel 3 loose on a layshaft 4 common to the first and second mechanisms. Transverse manipulation of lever 13 may bring about, through displacement of a selector bar 5, Fig. 2, either engagement of shaft 1 with pinion 6 loose on output shaft 7, or the engagement of pinion 3 with the layshaft 4. This shaft carries a pinion 8 meshing with pinion 6, and also a pinion 9 meshing with a pinion 10 loose on shaft 7, on which is a sliding member 11 provided with a synchromesh device and connected to a selector bar 12, Fig. 2, controlled by longitudinal movements of lever 13. Means are provided, adapted to come into action during a change of gear in the first mechanism, and when the second mechanism is in neutral, to ensure at that moment the braking of at least certain of the elements which rotate idly during this period. The element to be braked is preferably the input shaft 1. On the selector rod 5 is a cam 16, Fig. 2, co-operating with a plunger 17, so as to press on this plunger when the rod is between its positions corresponding to the two speeds of the first mechanism, the plunger acting on a band 14 to brake a pulley 15 on shaft 1. The plunger 17 is urged by a spring 18 to act as a catch to engage notches 19, 20 and retain the rod 5 in position. To prevent damage in the event of the braking member being brought into action when the main clutch has not been thrown out, the selector rod 12, Fig. 2, controlling the synchromesh mechanism, has a catch 21 co-operating with three notches 22 ... 24, the middle notch corresponding to neutral of the second mechanism. In a modification, Figs. 6, 7, the first mechanism is of the three-speed type. On the input shaft 50 are two pinions 51, 52, the first being integral with, and the second slidable on the shaft. These pinions mesh respectively with pinions 53, 54 loose on a layshaft 55, the pinion 54 being slidable on shaft 55 and partaking of the sliding movements of pinion 52 both having double helical teeth. A slide 57 loose on a ring 56 is movable by a member 58 and carries dogs 59, 60 by which the pinions can be connected to the layshaft at will. The synchromesh mechanism is of the two-speed type and comprises on the input shaft 62 a pinion 63 engaging a pinion 64 on secondary shaft 55 on which is mounted a pinion 65 meshing with a pinion 66 on the output shaft 67, a dog-system of synchromesh type actuated by a fork 68 being provided to connect either shaft 62 or pinion 66 to output shaft 67. To pass from the group of first and second speeds to the group of third and fourth, the slide 57 is displaced and the pinions 52, 54 are in that position in which pinion 52 is not connected to input shaft 62. To pass from the group of third and fourth to the group of fifth and sixth speeds, the slide remains in the position it occupied for the preceding group and the pinions 52, 54 are moved so that 52 engages with input shaft 62. These changes may be effected by a hydraulic control comprising a lever 69 co-operating with a gate 70 having six notches for forward speeds and a transverse slot for neutral, the lever 69 and fork 68 being so interconnected that 68 is in neutral when 69 is in the transverse slot. A distributer 71 ensures that, according as lever 69 is opposite one or other of the six notches, the forked members 58, 61 are made to occupy that position which renders effective one or other of the three speeds of the first mechanism. A braking device 76, 77 may be provided on the input shaft, the brake being applied when lever 69 is between the rows of notches. A similar brake may be provided on the layshaft 55. The synchromesh device is of the type in which the sliding dog assembly 100, Figs. 6, 7, is connected to the grooved member 101 by radial arms 102 passing through openings 103 in a sleeve 104 which supports friction cones 105, 106. The openings 103 are so shaped that they extend to one of the ends of sleeve 104. To facilitate further the assembly of the parts, the cone 106 is fixed on sleeve 104 before the latter is in position. One end of sleeve 104 is provided with a continuous peripheral toothed cheek or web 107 to allow the arms 103 to be passed therethrough. A plate 109 carrying cone 106 may be fixed to this cheek. The sleeve 104 and plate 110 are formed separately to pass the member 101 and, for this purpose there is no protruding cheek at that extremity of sleeve 104. The gear may have a reverse as described in Specification 403,422 but a simpler form may be employed by keying a pinion 150, Fig. 1, to the output shaft, and arranging it opposite a pinion 151 keyed to the layshaft, a sliding pinion 152 being arranged to connect pinions 150, 151 by means of a forked member integral with the selector rod 154, Fig. 2. In the construction described in Specification 403,422, it was arranged that the gear lever 13 could engage in a slot 155 in selector rod 154 after it had been moved to release the end 156 of the lever from fork 157, in order to prevent the supplementary movement of the lever when passing into the lateral notch of the reverse gear from effecting an additional sliding movement of the rod 5 and the members it controls. In the present construction, the entrance 158, Fig. 5, of the lateral reverse notch is in line with the neutral position of the forward speeds.