Patent GB-476604-A (GB)
Title: Improvements in and relating to control devices for variable speed gearing
IPC: F16H61/02
Filed: 1936-06-13
Abstract: 476,604. Change-speed gearing. BONN, C. R. H. June 13, 1936, No. 16551. [Class 80 (ii)] In change-speed epicyclic gearing of the kind, such as that described in Speoification 418,505, comprising a number of gear trains, each having a braking- member 9 .. 9<3>, Fig. 1, adapted selectively to engage a common co-operating braking-member constituting a casing 1, the said casing yields under torque reaction and thereby controls means effecting the automatic selection of the brakes. Pressure - fluid resists the yielding movement and hydraulic means are provided whereby, during an upward change, a supplementary throttle of a driving internal-combustion engine is automatically closed, or a retarding-switch of a driving electromotor is automatically actuated. Manual selector means, utilizable only when the automatic action has been rendered ineffective by an interlocking arrangement, is also provided. The control is wholly hydraulic only, and a hydraulic relay is also provided for operating the distributing-valves controlling the speeds. As in the above-mentioned Specification the brake members 9 .. 9<3> comprise cones selectively moved axially into frictional engagement with the casing 1 by supplying pressure oil to the casing on the larger-diameter side of a selected cone and exhausting from the other side, under the control of separate rotary distributing-valves, 24 for inlet and 25 for exhaust, connected together by toothedwheels 68. A direct-drive clutch 9<4>, carried by the driving shaft 2 is similarly controlled, 3 being the final driven shaft. The rotary yielding movement of the casing 1 is resisted by pressure-oil in a transverse cylinder 5, secured to the periphery of the casing, the piston rod 10 of the cylinder being pivoted to one arm of a bell crank lever 11, carried by the casing 1 and having its other arm connected by a link 13 to a fixed point 13<1> on the frame. A compression spring 14, on the exhaust side of the cylinder, assists the casing in opposing the oil-pressure. The pressureoil is supplied through a regulating - valve 7 by the same pump 32 which supplies the distributing-valves and brakes, a two-stage adjustable pressure-relief valve 117 being provided. The distributing-valves 24, 25 are themselves carried by the casing 1 and are operated, through a hydraulic relay described below, by turning a pinion 17, engaging a stationary arcuate rack 18, Fig. 6, the pinion being spaced from the axis of the casing, so that, as the latter yields under torque - reaction, the pinion is tracked bodily along the rack and is thus turned to effect selection in the manner described below. When the operator desires to effect manual selection, he first turns a shaft 26, Fig. 5, rigidly carrying a slide 19<1>, supporting a slipper 19 on which is pivoted the rack 18, which rack is thereby moved from the concentric automatic position (shown in full lines, to substantially radial manual positions (shown dotted) in which latter positions the bodily movement of the speed selecting pinion 17 as the casing 1 yields, does not cause it to be rotated to change speed, its only effect being to pivot the rack idly about the slipper 19. In the manual position the pinion 17 is turned to select a new speed, by manually moving the slipper 19 along the slide 19<1>, thus tracking the rack 18 over the pinion 17, the movement of the slipper being controlled by turning a manual speed-selecting shaft 29, rigidly carrying a plate 28, connected by a link 30 with the slide 19. An interlocking lever 36 co-operates with notches 35, 34 in the plate 28, and a plate 33, secured to the shaft 26, in such a way that the plate 28, and so the manual selector-shaft 29 cannot be turned until the shaft 26 has been manually turned to move the rack 18 from the automatic to the manual position, and further that the shaft 26 cannot be turned from the manual to the automatic position until the shaft 29 has been turned to neutral, the subsequent movement of the rack from manual to automatic position serving to rotate the selector-pinion 17 from neutral to low-speed or vice versa. Abutments 145 carried by the shaft 26 co-operate with fixed pins 69 to limit its movement, and spring pins 124, 125 locate the shafts 29, 26 in neutral, and manual or automatic positions respectively. The distributing-valves 24, 25 are similar to those described in Specification 418,505. Their spindles 46 rigidly carry intermeshing gear-wheels 68, Figs. 1 and 2, which themselves constitute a fluid-pressure relay motor, arranged in a secondary hydraulic circuit and energized in either direction from the primary circuit, under control of a two-way valve 94, Fig. 2, operated by the selector pinion 17, for the purpose of loading the distributing-valves and subsequently moving them to a selected position when the said valves have been mechanically unlocked, also by the selector-pinion 17. This hydraulic loading and mechanical unlocking of the distributing - valves is similar to that described in Specification 476,606, being performed as follows. The selector-pinion sleeve 73, Fig. 2, has an integral axial projection 78, Fig. 17, carrying a roller 116, (see also Fig. 2), engaging a helical groove 115 in a sleeve 114, which has also an axial groove engaged by a roller 129, Fig. 16, rigidly carried by an extension 61 of one of the selector-valve spindles 46, so that the immediate effect of turning the selector-pinion sleeve 73 is to move the sleeve 114 axially in either direction, which movement through a roller 112, Fig. 17, lever 111, Fig. 2, and yoke 109, operates a two-way valve 94, thus loading the selector-valve motor 68 in one direction or the other. As shown in Fig. 2, the valve 94 is normally in position to energize the motor 68 in the direction indicated, for a downward change and leftward movements of the sleeve 114 do not affect the valve, the lever-engaging yoke having an idle gap for this purpose. The selector-valve spindle 61 is normally locked by a spring-loaded tooth 62, Fig. 17, on a yoke 66, pivotally carried by the spindle 61, the tooth 62 engaging one of a series of facial locking notches 57 on a fixed plate 55. After the selector-pinion sleeve 73 has turned one complete step in either direction, it releases the locking-tooth 62, whereupon the selector-valve spindle 61 follows up the step under the influence only of the hydraulic loading on the motor 68, the locking-tooth then re-engaging a notch 57 to lock the new speed. Such locking and releasing is effected as follows. Freely mounted on the selectorpinion sleeve 73 is a cam-disc 85, always turning with the sleeve by virtue of a slot-androller connection 87, and having a speciallyformed cam-surface 89 tracked by a roller 92, rigidly associated with the locking-tooth 62, the spring of which urges the roller against the cam-track. The selector-pinion sleeve 73 pivotally carries a bridge-member 79 carrying a roller 63, which tracks a series of selectivelyplaced projections 56 on the fixed plate 55, the bridge-member being also operatively connected to a depending pivoted arm 80 for moving the cam-disc 85 axially. Also yieldingly carried by the selector-valve spindle 61 is a pin 70 normally spring-pressed into engagement with a recess in the cam-disc 85. At the commencement of a speed-changing operation, the roller 63 is on the apex of a projection 56, as shown in Fig. 17. Immediately the selector-pinion spindle 73 is turned, the roller 63 rides down the projection 56, retracting the depending arm 80 away from the cam-disc 85, which is then urged to the left by virtue of its cam-face turning over the spring-urged roller 92. This leftward movement disengages the cam-disc from the pin 70, leftward movement of which is limited by a stop, and the cam-disc is thus allowed to continue its rotation without affecting the selector-valve spindle 61. Such rotation continues until the roller 63 reaches the projection 56, corresponding to the next speed, neutral or reverse, whereupon it rides to the apex of the projection, tilting back the arm 80 which returns the cam-disc 85 axially to the right, and, through the roller 92, disengages the locking-tooth 62 from its notch 57 and frees the selector-valve spindle 61. Under the influence of the hydraulic loading of the motor 68, energized by the valve 94 as above-described, the selectorvalve spindle 61 then rotates until the pin 70 again enters the recess 93, and the roller 92 falls into the cam-recess 89, permitting the locking-tooth 72 to engage a fresh notch 57. The selector-pinion sleeve 73 is retained in gear positions by a spring-pressed detent, engaging its periphery 75. In this construction, the pin 70 functions to apply a drag to the angular movement of the cam-disc 85. In a modification, also shown, the pin 70 engages in the recess 93 only when the cam-disc occupies positions on either side of neutral between first and reverse speeds. The purpose of this is to initiate rotation of the distributing-valves from neutral, positively through the pin 70, thereby closing ports which, in the neutral position of the valves, allow the fluidpressure to escape. Closure of these ports creates a pressure-rise and loads the motor 68 for subsequent operation. In both forms, during a speed-change both sides of the gear-casing 1 are temporarily exhausted, so that the pressure in the primary hydraulic circuit falls. In order to store sufficient pressure to load the selector-valve motor 68, the input 103, Fig. 2, of the secondary circuit of the motor 68 comprises a spring-loaded hydraulic accumulator 95, connected by a one-way valve 96 with a conduit 102, connected to the primary circuit via the inlet distributing-valve 24. The hydraulic mechanism for closing the supplementary engine-throttle 141 (or electro-motor control switch) during an upward change, comprises a cylinder 138, which at all times, except during an upward change, is ene