Patent GB-444876-A (GB)
Title: Mechanism for automatically changing the speeds in the gear box of a machine having a motor
IPC: F16H61/02
Filed: 1934-06-28
Abstract: 444,876. Controlling change speed gearing. BAZZI, P., 14, Rue de la Republique, Saint-Etienne, Loire, France. June 28, 1934. No. 19169. Void [Abridged as open to inspection under Sect. 91 of the Acts, Dec. 29, 1934]. [Class 80 (ii)] [See also Group XXXII] Variable-speed gearing, for a motor vehicle, is controlled automatically by a centrifugal governor 1, on the driven-shaft X, which operates through a power-driven cam-relay on the strikers of the gear 228, which is not described. During a change, the main-clutch 313 is automatically disengaged and synchronizing-means are rendered effective. The synchronizing-gear is so interconnected with the control of the power-relay, that it stops the relay when it has disengaged the old speed and only starts it again to re-engage the new speed when synchronization is complete. Means are provided for manually engaging first-speed or reverse at the start; for rendering the governor inoperative in reverse; for preventing the governor from disengaging the first-speed at very low vehicle-speeds ; for fixing the gear in any speed independently of the governor, the last named means being interconnected with the service-brake to prevent the gear changing whilst the brake is applied ; for manually returning the gear to a neutral zero position ready for a fresh start after the vehicle is stopped; and for preventing the governor from attempting to engage one speed before the previous one is fully engaged. The shaft 155, Fig. 1, of the power-relay is driven in either direction from the drivenshaft X through worm-gearing 152 and a bevel reversing-gear 159, controlled by frictionclutch-levers 151, 151<1> operated by oppositelyrotating cams 60, 60<1>, each provided with identical oppositely-rotating gearings, I, J, I<1>, J<1>, Fig. 6, one being for upward and the other for downward changes. One of the gears I, J, is shown in Fig. 7 and comprises a shaft 50 splined in a worm-wheel 49, constantly driven by the shaft X. The cam 60 forms part of a sleeve 58 provided with a friction-disc 57, adapted to engage a similar disc 55 rigid with the shaft 50. This shaft 50 is axially movable to engage the friction surfaces 55, 57, and is normally maintained, in the upper position, against pressure of a spring 56, by a detent 77 which engages a projection at the side of the shaft. When a change is to be made the governor tilts an arm 106, Fig. 6, serving as a trip for a pin 91 on a drum 88 containing a stressed spring 89, connecting it with a stationary sleeve 87. The release of the drum causes it to rotate and a tooth 102 thereon pulls down a bar 79 which retracts the detent 77 and allows the shaft 50 to fall, taking with it a retaining-pin 72, Fig. 7, for holding a projection 61 of the cam 60 in either of two bevel-sided recesses 71 in a fixed plate 68. Simultaneously the friction-discs 55, 57 engage and begin to drive the cam 60. The projection 61 thereon cams itself out of the recess 71, thereby immediately lifting the shaft 50 to its upper position, by engagement with a collar on the shaft, which passes freely through the camsleeve 57. The cam 60 continues to rotate until it reaches and operates the relay clutcharm 151, Fig. 1, and at this point the projection 61 drops into the other recess 71 in the plate 68, thereby releasing the friction discs 55, 57. In the meantime the spring- loaded detent 77 has re-engaged the shaftprojection to hold the shaft 50 in the upper position. After 90‹ revolution of the powerrelay, which is sufficient for a gear disengagement, Figs. 20 and 21, a rod 99, Fig. 6, is pushed downwardly by means described below and acts on a projection 149 to push down the rod 79 so that the detent 77 is again removed and the shaft 50 falls. The projection 61, Fig. 7, is caused to move in the same direction into the first aperture 71, and subsequently by a further movement of the rod 99 again to the second aperture 71 to re-engage the fresh gear and finally back to the first aperture thereby making two complete revolutions. The first and second movements of the rod 99, which effect the second and third releases of the shaft 50 during a single gear change, are controlled by the synchronizer, in a manner described below. The third downward movement of the rod 99 is obtained by a doublelobed cam Figs. 20 and 21 (not shown), driven by a geared shaft 170, Fig. 1, of the relay. After each downward movement, the rod 99 is returned to the upper position by a wheel 96, having appropriately-spaced teeth and rotating with a shaft 81, geared at two-to-one, through wheels 63, 80, with the cam-sleeve 57 and serving to pivot an arm 97<1> about the shaft 811 of the indentically opposite gear, both arms 97 and 97<1> acting on the rod 99 through a projection 98 thereon. In order that the rod 99 may operate the detentrelease-rod 79 or 79<1> of either gearing I or I<1>, there is a swinging-frame 148 carrying pivoted arms 145, 145<1> passing between pegs on the detent release arms 79 and arranged so that either one arm can engage an operative projection 149 on the arm 99. The frame 148 is automatically swung selectively to either side by cam-wheels 95, 95<1> on the shafts 81 81<1>. The two complete revolutions of the shaft 50 necessary for a gear-change, cause one revolution of the shaft 81 causing the above-described release-movements and also serving, through an arm 85, to wind up the spring 89 which gives the first release movement, under control of the governor. The governor 1, which is described later, serves to swing an arm 28, Fig. 2, carrying a slider y which moves over an arcuate path and is connected, yieldingly in one direction and positively in the other, with a second slider z, which is similarly connected with a third slider n. The slider z is carried by a freely-pivoted arm 29. All the sliders normally slide together, and the slider y has three teeth 33, operating, only in the direction of ascending speeds, on a pawl 116 on the trip-arm 115. The slider z has four teeth, which are directly under the teeth of the slider u, operating, only in the direction of descending speeds, on a pawl 111, carried by the trip-arm 106 of the gearing I, J. The slider u has also four teeth 31 which co-operate with pawls 135, 135 on a pivotal arm 133 secured to a spring-pressed arm 136, acted upon by a bell-crank 138, Fig. 6, which is depressed by the cam-wheel 100 on the shaft 81 only once during a complete revolution of this shaft, i.e. during a complete gear-change. Thus only one tooth of the slider u may pass a tooth 134 or 135 at a time, in the direction of descending speeds, and a change must be complete before the next can be initiated. The relay striking-mechanism Figs. 17, 18 and 19 comprises striker-rods 183, 184, yielding four forward speeds, an independent rod 432, Fig. 1, being used for the wholly manual reverse. The rods 183, 184 can both slide and turn in bearings on the base-plate and have arms 179, 180 carrying balls 175, 176, which arms pass through a slotted guide-plate 191, movable longitudinally of Fig. 18 to tilt the arms and bring either of the balls 175, 176 into the fixed plane of a pair of eccentrics 174, 173 secured respectively to the powerrelay shaft 155 and to a parallel shaft 170 geared to rotate oppositely thereto at an equal speed. A 180‹ movement of the eccentrics moves a rod 183 or 184 axially from one gear and into another. The longitudinal selective movement of the guide-plate 191 is effected in timed relation to the striking- movement, by arms 202, 205, on the shafts 155,170, having wedge-ends 201, 204 acting one-way only on spring- pressed pawls 200, 207, on slidable end-plates 195, 194 which carry the guide-plate 191. Continuous rotation of the shafts 155, 170 always in the same direction, changes the gear upwardly throughout its range of four speeds, and continuous opposite rotation changes it downwards. For the purpose of bringing the gear to a neutral zero position, the powershaft 155 of the eccentrics carries a pair of radial plates 290, 291, Fig. 1, arranged at a right-angle to each other. By pressing a foot-pedal a rod 435 is pulled upwardly and acts, through an arm 299, to tilt an S- shaped arm 292, 295, which engages both plates 290, 291, and draws them into a neutral position. Manual means are provided for engaging first-speed from this position and comprise a rod 397, acting on a single S-arm 296, capable of moving the plate 291 through 90‹ to engage first-speed. The main-clutch and the synchronizer are both operated by a shaft 234, Fig. 1, geared up at four-to-one to the power-shaft 155 of the relay, the pinion 233 which drives the shaft being connected thereto through a cone friction-clutch 490 which is released whenever the gear is manually returned to the neutral zero position, or whenever first-speed or reverse is engaged. The main-clutch release gear comprises a rod 239, Fig. 27, which is pulled downwards, to disengage the clutch, by rotation in either direction of a two-armed lever 277, secured to the shaft 234 and co-operating with spring- loaded pawls on a semicircular extension of the clutch-rod 239. The rod 239 is held in the disengaged position by a spring-loaded detent 286 which is released at the end of a gear-changing operation by teeth 289 spaced 180‹ apart in a helical groove in a sleeve 281 secured to the shaft 155, the teeth acting to push back a pin 283 slidable in the end of the detent 286. The lever 277 makes two revolutions during a gear change, but the second one will be ineffective, since the rod 239 is latched down. The re-engagement of the clutch is cushioned by a dashpot, described below. When starting from rest in first-speed or reverse, the clutch is operated manually by means of a pedal 371, Figs. 37 and 38, which also turns a ring 381, which is axially slidable into operative engagement with either of two rods 397, 398 respectively for first-speed and reverse, the axial sliding being eff