Patent GB-416663-A (GB)
Title: Improvements in and relating to motor vehicle transmission and control systems
IPC: F16H61/02
Filed: 1933-01-19
Abstract: 416,663. Controlling change-speed gearing controlling clutches. GILLETT, E. H. J. C., 32, Marlborough Mansions, Cannon Hill, London. Jan. 19, 1933, Nos. 1823/33, 32753/33, and 773/34. [Class 80 (ii).] Relates to change-speed epicyclic gearing for vehicles of the kind in which friction elements such as brakes and clutches are selected by manual means such as a lever 103, Fig. 1, on a gear casing 12 and engaged one at a time alternatively by an executive control such as a lever 120. The drive in such gearing is disconnected automatically by power means when the engine speed falls sufficiently. The drive may be disengaged by releasing a brake in the gearing itself when there is no engine clutch, or by releasing an engine clutch in a casing 11 when there is such a clutch. The power means is an hydraulic servomotor 22 with centrifugal weights which acts to turn a lever 26 clockwise, which through a linkage 27, 119 turns the executive control lever 120 anti-clockwise, and so disconnects the drive. When there is an engine clutch, the pull in the link 27 from the servomotor tilts the clutch pedal lever 13, which has a cam lobe 13<a> which passes under a bowl 16<b> on a clutch-disengaging lever 16<a> so as to disengage the clutch without transmitting the stress of the clutch spring back to the servomotor, which is then free to deal with change gearing only. The manual selection is imparted to the lever 103 through a rod 100 and worm gear 100<a> by turning a hand lever 97 over a quadrant 96. The executive control lever 120 and also the clutch disengaging lever 16<a>, if present, are commanded by the pedal lever 13, a full depression of which disengages all the brakes of the change gearing, and also the clutch, if present, said pedal lever 13 being operated by the servomotor 22 which acts automatically to disengage the drive by a partial movement and also as a relay under manual control for full or additional speedchange effecting movements. The accelerator is shown at 14 with connections 21, 30 to an accelerator relief valve for the servomotor. The hand selector lever 97 is connected by links 117, 34 to a stem 32 for controlling the volitional power stroke in which the servomotor 22 acts as a relay to effect the said additional executive movements. A belt 24 driven by the engine 10 drives a pulley 23 fast on the shaft 45, Fig. 3, of a pump 47 which drives oil from a reservoir 22<a> through a duct 50 delivering to an annular chamber 62 which surrounds the valve 70, 72 and through a duct 64 communicates permanently with a power cylinder 58. The valve 70, 72 is a follow-up device with a combined centrifugal and manual control. A piston 59 acts on a lever 65 and rock shaft 66, Fig. 4, so as to displace the lever 26, Fig. 1, clockwise against the springs in the casings 12 or 11. The servomotor acts when the pressure chamber 62, Fig. 3, is not vented through the follow-up valve and through a central passage 61 to the reservoir 22<a>. Centrifugal weights 52 carried by a bell 51 on the engine-driven shaft 45 move outwards as far as the bell will allow and act to thrust leftwardly and together a sleeve 56, a thrust ball 75, and a central valve-actuating rod 73 all against springs 77, 78. The automatic action is partial, being limited by the bell stopping the weights. Leftward and rightward movements of the rod 73 are imparted to an inner valve sleeve 72 respectively by a spring 74 and by a collar 85, Fig. 3<a>, screwed on the rod 73. The inner valve sleeve 72 acts to close ports 71 in an outer valve sleeve 70, the effect of which is to build up pressure behind the piston 59, consequent movement of which through studs 68, Fig. 4, makes the outer sleeve 70 follow the inner sleeve 72 so as to reopen the ports 71 and stop the movement. Thus, with the weights 52 expanded by engine speed as shown in Fig. 3, and the ports 71 open, the piston 59 is not moved. When the engine speed falls sufficiently, the weights 52 fall in to the position shown in Fig. 7, whereby the inner sleeve 72 moves rightwardly and closes the ports 71, whereupon the piston moves leftwardly and the outer sleeve rightwardly and all stop in the position shown in Fig. 7 with the ports 71 just open and the piston in a position corresponding to a partial rightward throw of the levers 26, 120, Fig. 1, sufficient to disconnect the drive. This action is progressive and the gear brake or engine clutch may be allowed to slip in a progressive manner according to engine speed. The purpose of the accelerator relief valve 92, Fig. 3, is to prevent continued slipping under heavy loads. As shown in Fig. 3<a>, a pin 88 fast to the inner valve sleeve 72 passes through a slot 89 in the rod 73. The collapsing of the weights 52, Fig. 7, has caused the parts 56, 75, 73 to be moved rightwardly together by the spring 74 so that the collar 85 is against the end of the sleeve 72 and the left end of the slot 89 is against the pin 88. The slot 89 is to allow the manually-controlled full-stroke by power necessary for a speed change to be superposed on the automatic partial stroke to disengage the drive merely. If the engine is speeded up from the position of Fig. 7, the parts come to the position of Fig. 3 with the weights expanded, but the pin 88 still at the left end of the slot 89. If now the selector lever 97, Fig. 1, is raised from a notch 96<a>, Fig. 9, in the quadrant 96, a pull is imparted to the link 117, Fig. 1, and a push to the stem 32, Fig. 3<a>. This thrusts the pin 88 to the right end of the slot 89, as shown in Fig. 8, with the spring 74 compressed. The inner sleeve 72 then moves the whole length of the slot 88, which is the same as the width of the chamber 62. First this closes the ports 71 so that pressure oil acts behind the piston 59. This piston must move to the full stroke position shown in Fig. 8 before the outer sleeve 70 has followed the inner sleeve 72 sufficiently to stop the piston movement with the ports 71 just open as shown. The partial stroke to disengage the drive takes place at any time on slowing the engine. To change speed, the lever 97 is first lifted out of a locking notch 96<a>, Fig. 9. The full stroke of the servomotor 22 then disengages the speed in action fully. In the case of a Wilson gear box, the busbar is thrust right down. The selector lever 97 is then turned for selection, which in case of a Wilson gear, turns a cam shaft which thrusts a strut into the path of the busbar. The lever 97 is then depressed into another locking notch. This allows the springs in the casing 12 to raise the busbar and bring in the selected speed, and the clutch spring in the casing 11 to engage the clutch, if present. A slot connection 28, Fig. 1, allows the pedal 13 to be depressed manually to disengage the clutch, if present. In a modification shown in Fig. 10, the lever 97 is not raised, but the power stroke is effected by compressing an auxiliary lever 121, so that the selector and executive control motions may be simultaneous. Specification 402,794 is referred to in the complete Specification, and Specifications 334,894, [Class 80 (ii)], and 395,692 in one of the Provisional Specifications. According to a Provisional Specification, a change-speed gear of the kind described may be combined with a fluid flywheel.