Patent GB-415578-A (GB)
Title: Improvements in and relating to variable speed gearing
IPC: F16H29/04
Filed: 1933-08-11
Abstract: 415,578. Variable-speed gearing. LAUB, A., 25, Margarethenstrasse, Basle, Switzerland. Aug. 11, 1933, No. 22439. Convention date, Dec. 1, 1932. [Class 80 (ii).] In variable-speed ratchet gearing such as that described in Specification 316,833, [Class 80 (ii)], wherein a driving swash-plate 5, Fig. 1, is tilted, to vary the speed, by axial movement of a controlling-body 25, the latter is moved by the power of the driving-shaft through a relay, rendered operative by a manual control-lever 82. An emergency manual-control and a rapidaction manual change-down are also provided. As in the above-mentioned Specification, the control-body 25, which rotates with the driving- shaft, is provided with clutching-teeth 37, to engage with teeth 35 on a disc keyed to the driven-shaft 2, for providing a direct-drive, whereupon the swash-plate is returned to the inoperative perpendicular position, the powerrelay is automatically disengaged and the control-lever 82 is returned to a central position. The swash-plate is carried on a transverse trunnion 4 on the shaft 1 and is tilted through a lever 53, rigid with the swash-plate and having a kidney-shaped cam-slot 52 overlying a similar slot 54 in the control-body 25, the slots being connected by a pin 55 passing through a slot in the shaft 1. Hence in both extreme positions of the control-body, the swash-plate is perpendicular to the shaft. The swash-plate carries a non-rotating sliding-ring 6, guided by rollers 7 thereon and fixed guides 8, and driving, through links 25 and roller ratchets, bevel wheels 10, 10<a> adapted to be clutched selectively for forward or reverse driving by a clutch sleeve k controlled by a manuallyturnable sleeve 84. Axial movement of the control-body 25 for tilting the swash-plate is effected by rotation of a pivoted toothed segment 59, acting on a rack 57 secured to a non- rotating ring 34 slidably carried by the controlbody. The segment 59 is tilted through a reversible power-relay in the following manner. For an upward change, the control-lever 82 is moved in the direction alpha, thereby moving vertically a rack-ended rod 80<a>, which turns a small toothed wheel 79, Fig. 4, to move a rackended slide 76, having an inclined rib 75 which imparts movement to a slide 73 axially of a transverse-shaft 66 and thereby serves to clutch a bevel-wheel 67 or 68, Fig. 8, to the shaft 66, according to the direction of movement of the control-lever. The shaft 66 is driven from the main power-input shaft 1 through spur-gearing 1<a>, 1<b>, Fig. 1, and worm-gearing 177, 69. The bevel-wheels 67, 68, Fig. 8, both mesh with a single bevel-wheel 65, Fig. 4, which drives a shaft 60 through irr versible wormgearing 64, 62, and the shaft 60 carries a pinion 61 gearing with the control-segment 59, Fig. 1. The shaft 60 also carries a toothed-wheel 122, Fig. 1, gearing with a toothed part 108 of a cam-wheel 107, one purpose of which is to disengage the power-relay and return the control-lever to the central position. For this purpose, there is a lever 103, Figs. 1 and 3, having a lug 106, and pivoted at a fixed point 102 and at the point 104 to the slide 76 which operates the power-relay clutches for the bevel-wheels 67, 68. In the position for increasing the ratio in forward drive, with the control-lever 82 in the position alpha, the slide 76 is moved to the right in Figs. 1, 3 and 4 and the lug 106 is rightwards of its central position, Fig. 1. The consequent operation of the power-relay causes the cam 107 to rotate in an anticlockwise direction through approximately 270‹, and takes the swash-plate from an idle position to direct-drive. Thereupon a lug 107<a> on the cam 107 strikes the lug 106, turning the lever 103, to disengage the bevel wheel 68 and return the control-lever to the central position. The gear can thereafter be changed down in a similar manner by forward movement of the control-lever to clutch the oppositelyrotating bevel-wheel 67, or if a rapid changedown is required, the pedal 130, Fig. 11, is depressed to rock a segment 128 and rotate a toothed-wheel 119 secured to the shaft 110, Fig. 9, on which the cam 107 is freely mounted. This action causes an initial disengagement of the relay-gear in the following manner. To the shaft 110 is secured a lugged disc 111 having a part received in a recess in the cam 107 and carrying a lug 111<a>, Fig. 14, adapted to engage against an internal lug 109, Fig. 15, in the camrecess. The boss of the lugged disc has a notch 112 in which normally engages the nose 113<a>, Fig. 16, of an element 113 which is forked to embrace the shaft 60, see Fig. 5, and has a flange overhanging another forked element 117, sliding in a groove in a clutch-element 118, splined to the shaft 60 and normally clutching the worm-wheel 62 to the shaft 60. The element 117 also has inclined radial projections engaging inclined grooves 115, Fig. 16, in the flange of the element 113, so that a partial turn of the latter, against the force of a returnspring 116, withdraws the clutch-element 118 axially out of engagement with the worm 62, thereby disconnecting the power-relay. This partial turn is effected by the initial depression of the pedal 130, which causes the nose 113<a>, Fig. 16, of the element 113 to move out of the notch 112 in the rotating disc 111. The lugged disc 111 continues to turn and then causes rotation of the cam 107 by interengagement of their lugs 111<a>, 109, thereby tilting the swash-plate. The pedal 130 is returned by a spring 131, Fig. 11, and the reverse action brings all the parts back to the initial position. The clutch sleeve k, Fig. 1, for forward, reverse or neutral is operated by turning, in one direction or other, a sleeve 84, mounted beneath the control-lever 82 and serving to turn an internal shaft 83, Fig. 5, having an eccentric end-pin 83<a> depending into a slot in a lever 87 pivoted at 86. This lever is pivoted at its other end to two push-rods 89, 90, Fig. 3, acting, through springs 91, 92, on slides 93, 94, and it first moves the slide 93, when possible, and simultaneously compresses the spring 92 of the slide 94, which latter has a forked lower end 94b, Fig. 7, directly connected through a rock-lever 98, Fig. 1, and a rod S, with the clutch-sleeve k. The slide 94 cannot move until the slide 93 has pivoted a bell-crank lever 95, Fig. 7, so that a pin 101, on the free end of a pivoted arm 100, moves from a central position into the upper part of a stepped aperture 94<c> in the slide 94. The slide 94 is then free to be moved by its spring 92 to operate the clutchsleeve k. In order to move the clutch-sleeve to neutral from an operative position, the pin 101 on the arm 100 must be withdrawn, to the left of Fig. 7, sufficiently to allow the spring 91 of the first slide 93 to swing the bell-crank lever 95 to a horizontal position and thereafter permit the spring 92 of the second slide 94 to operate. For this purpose the arm 100 is mounted on an eccentric boss 67<a> of the relay bevel-wheel 67 and the control-lever 82 is operated to cause rotation of this bevel-wheel before neutralizing can take place. In the event of failure of the power-relay, the bevel-wheel 67 can be manually rotated for this purpose and also to return the parts to the zero position by turning a stubshaft 66<a>, Fig. 8, connected by clutch-teeth with the bevel-shaft 66. The slide 94 moves together with a similar slide 123, Figs. 1 and 5, the former having a forked end resting on a part of the casing. The parts all move in the opposite direction for obtaining reverse. Various automatically-released catches or stops prevent engagement of the clutch sleeve k with the forward drive clutch m under certain conditions. For instance, when the swash-plate controlling-body 25, Fig. 1, reaches the directdrive position, a part of it abuts directly on the end s of the rod S and moves the clutch-sleeve k to neutral position, the swash-plate simultaneously returning to the perpendicular, no-drive position. Under these conditions if, on changing down, the clutch-sleeve k were allowed to engage freely following disengagement of the direct-drive, a clash would result and, to prevent this, re-engagement of the clutch-sleeve k is prevented until the bevel gear-wheels 10, 10<a> have been brought up to speed. For this purpose, the coupled clutchactuating slide 123 carries a pivoted stop 124 having an enlarged nose 124b, Fig. 18, and a notch 124<c>, engaging between nose-members 126, 127 on fixed pivots 125. The noses 124b and 126<c> are simultaneously pressed downwards by a spring 126b, and the member 126 has an extension 126<a>, Fig. 19, which presses upwards on the surface of the cam 107. Prior to the downward change, the part 126<a> rests on a dwell-part 107b, Fig. 15, of the cam 107, with its nose 126<c> in the notch 124<c>, preventing leftward clutch-engaging movement of the slide 123. A predetermined rotation of the cam 107 for the downward change, causes the part 126<a> to ride up a swell 107d of the cam and so release the stop 124 and allow the coupled slides 123, 94 to engage the clutch sleeve when the swashplate is sufficiently inclined to the shaft. When driving in reverse, such a stopping movement is not provided and the controlling-body 25 is positively prevented from ever reaching the direct-drive position. For this purpose, the nose 124b of the stop 124 lies between the noses of the members 126, 127, since the slide 123. has been moved to the right, Fig. 1, to engage the clutch-sleeve k with the reverse clutch-member m<1>. Before the control body reaches the direct-drive position, a swell 107<c>, Fig. 15, on the cam 107, causes the nose 126<c> of the member 126 to pivot upwards thereby turning the member 127 which abuts directly on the lug 106, Fig. 1, of the lever 103, which latter turns to disengage the bevel-wheel 68 of powerrelay and so prevents further speed-increase. The Specification as open to inspection