Patent GB-445770-A (GB)
Title: Improvements in and relating to change-speed gears
IPC: F16H3/08
Filed: 1934-10-08
Abstract: 445,770. Clutches; variable speed gearing. KREIS, F., 2, Wachterstrasse, Nuremberg, Germany. Oct. 8, 1934, No. 28816. Convention date, Oct. 7, 1933. [Class 80 (ii)] [See also Groups XXXI, XXV, and XXXII] Variable-speed gearing, more particularly for motor vehicles, comprises a transmission shaft 31, Fig. 1, having two sets of gear wheels 27-30, and 32-33 loosely mounted thereon and in constant mesh with corresponding gear wheels 24-26 of a driving member 14 and 36, 37 of a driven member 105, Fig. 9, characterized by a common control member 46 which can slide freely axially to select any speed ratio and is then rotated to lock the selected gear wheel of each set to the shaft 31 to bring the selected ratio into use. The arrangement constitutes two variable-speed gears in series. In the construction shown the driving member 14 of the first or bevel wheel variable gear is driven through an automatic centrifugal clutch 8 forming the subject of Specification 445,608. The second or spur wheel variable gear drives a differential gear 105, Fig. 9, and the differential shafts 111. 112 drive the road wheels of the vehicle. The gear wheels may be provided with helical teeth. Between each pair of gear wheels 27-28, 29-30 and 32-33 loosely mounted on the shaft 31 a coupling member 38 is keyed to the shaft, each member having three pairs of pawls 40 pivoted thereto on pins 41 and adapted to engage recesses 40<a> on the adjacent gear wheel to lock it to the shaft. One face of each pawl is sloped to allow the pawls being readily disengaged. The pawls are controlled by spring rings 43, Figs. 1 and 2 which tend to make them engage the gear wheel recesses, and they are moved outwards to disengage the recesses by means of plungers 49 sliding radially in holes in the coupling members 38. The plungers are operated by balls 48 also movable in the holes in the coupling members and coacting with grooves 47, in a slidable and rotatable control shaft 46. These grooves are shaped as shown in Figs. 7 and 8 and at their deepest parts are deeper than the radius of the balls 48. The control shaft 46 is rotatable through 60‹ relaytively to the transmission shaft 31 and when rotated to the neutral position all the balls are out of the grooves so that the shaft can be slid axially from any one gear position to any other. In this neutral position all the plungers 49 are forced outwards by the balls 48 so that all the pawls 40 are disengaged from the gear wheels and the latter are free on the shaft 31. The control shaft is rotated relatively to the shaft 31 by means of a control rod 50 which is slidable within shaft 46 and has two lugs 51, Figs. 1 and 5<a>, which pass through helical slots 70 in shaft 46 and engage a keyway 52 in shaft 31. Thus axial movement of the rod 50 causes rotary movement of the shaft 46 to the extent permitted by the length of the slots 70. For each gear change the rod 50 is first slid to rotate the shaft 46 to the neutral position, the shaft 46 is then slid to select any desired gear, and finally the rod 50 is slid back so as to rotate the shaft 46 to a position in which the selected gear wheels are locked to the shaft 31. The control shaft 46 and rod 50 are both operated by the gear lever 66, Figs. 9-11, which works in a guide or "gate" 89 and is pivoted at 65 to a shaft 63. A spring 87 normally keeps the lever pressed against one side of the gate in which there are recesses 88 corresponding to the different speeds. The lever is connected by a link 71, collar 73, and pin 75 to a rod 74 slidable within the shaft 63. To change gear the lever is swung about the pivot 65 and thereby slides the rod 74 which rocks a bell-crank lever 80 pivoted at 79 to the casing 60 of the gear. The bell-crank engages a pin 81 on a sleeve 61, and the rotation of this sleeve causes axial movement of the control rod 50 through a nut-and-screw connection 84 so as to turn the control shaft 46 to the neutral position. The gear lever is now moved to any selected gear position so as to rotate the shaft 63; a sector 62 on the shaft rotates a gear wheel 55 which forms a nut on a screw thread 53 connected to the shaft 46, so that rotation of the nut and gear wheel 55 slides the shaft 46 axially to the desired gear position. The gear lever is then released and the spring 87 rocks it about the pivot 65 to slide the control rod 50 and thereby rotate the control shaft 46 to its gear position in which the desired gear wheels are clutched to the shaft 31. A spring 86, connected between the shaft 46 and rod 50, assists the spring 87 to return the parts to their normal positions. The reverse gear can only be engaged when the gear lever has been moved slightly laterally to clear a stop 91 in the gate. The gearing can be locked against accidental movement in any direction by locking both spur gears 32, 33 to the shaft 31. This is effected by moving the gear lover sidewise in the part 95 of the gate, this movement causing two special recesses 96, Fig. 1 to be opposite the plungers 49 for the two spur wheels, so that these plungers are depressed simultaneously and both wheels are fixed to the shaft. The gear lever can only be moved to this locking position when a control rod 98 therein has been depressed so that a lug 99 fixed thereto clears a guide 100. The lever is held in this position by the lug 99 engaging a hole 101 in the gate. The Specification, as open to inspection under Sect. 91 comprises also the following features : (1) A modified construction of the centrifugal clutch 8, and means for controlling it, forming the subject-matter of Specification 445,608; (2) The change-speed gear may be controlled automatically by a centrifugal governor in accordance with the speed of the road wheels or the driven shaft of the gearing. Spur wheel gearing only may be used as shown in Figs. 25, 26 and 29 (all cancelled). A centrifugal governor 154 is mounted on the final driven shaft of the gear and rocks an arm 161 on a shaft 162 carrying a contact arm 163 working over an insulated sector 164. The arm has a spring-loaded ball 167 adapted to engage alternately speed position notches in the sector and intermediate electric contacts 166. Normally the first or low speed is engaged, one of the controlling balls 48 resting in one of the grooves 47 in the control shaft 46. The arm 163 is connected by a link 170 to a ring 172 pivoted at 173 to the field of a magnet A fixed to the control shaft 46, the ring 172 being located between opposing springs 174. The control rod 50, which must be moved axially to rotate the control shaft 46 to the neutral position before the shaft can be moved axially by the link 170 to change the gear, is fixed to the armature 175 of the magnet A which is energized by the ball 167 engaging any of the contacts 166. As the speed of the driven shaft rises the arm 163 is rocked towards the second speed position. The control shaft 46 is not yet moved by the link 170, one of the springs 174 being compressed instead. When the arm 163 reaches a contact 166 the magnet A is energized, and rod 50 is moved axially to rotate and release the control shaft 46, so that the arm 163 can move magnet A and shaft 46 to the second gear position. As the ball 167 leaves the contact 166 the magnet A is de-energized and rod 50 is returned by a spring so that the control shaft 46 is rotated and the second gear is engaged. As the speed increases the other gears are similarly engaged, and it is stated that finally a direct drive is obtained. For the reverse drive a magnet B is energized by a reversing switch. The throttle is closed, or the fuel supply reduced, at each change of speed, by a third magnet, energized each time the magnet A is energized. This subject-matter does not appear in the Specification as accepted.