GB419102A - Improvements in control mechanism for power-actuated variable-speed gearing suitable for use upon motor-vehicles - Google Patents

Abstract

419,102. Controlling change speed gearing ; controlling clutches. BENDIX AVIATION CORPORATION, 105, West Adams Street, Chicago, U.S.A. Feb. 4, 1933, No. 20601. Convention date, Feb. 6, 1932. Divided out of 417,648. [Class 80 (ii).] A first servomotor actuating change-speed gearing upon a vehicle, first set to determine the gear change, is energized to effect the gear change in consequence of closure of the engine throttle and simultaneously with disengagement of the engine clutch by a second servomotor. In the changespeed gearing, two speeds and reversed driving are effected in gearing in a box 84, Fig. 1, by sliding a gear 112, Fig. 2, which is connected by a rod 116 and bracket 120 to the piston rod 122 of the first servomotor 126. This is a follow-up device, the piston operating on connection to vacuum in accordance with the presetting of a valve button 138<2>, Fig. 3, effected through a Bowden wire 142, Fig. 1, from a preselector handle 150. The vacuum arrives through a pipe 138 which is connected at 74 to one end of the second or clutch servomotor 52, and also connected through a pipe 76 to the engine manifold 22 through a valve 78 operatively connected to a cross bar 72 on the throttle rod 28. Thus release of the accelerator pedal 30 to close the throttle 24 opens the valve 78 so that the servomotors 52 and 126 are simultaneously energized and the speed change for which the motor 126 has been preset is effected while the engine clutch in a casing 42 is at the same time opened. The gear change motor 126, Fig. 3, has its double-acting piston 124 secured to the piston rod 122 so that these parts in sliding carry with them the bracket 120 and vacuum pipe 138. The button 138<2> on the control wire 142 is arranged between lower and upper separately-movable valve slides 128, 1281 each having an annular duct groove. The groove in the upper slide 128<1> communicates with the atmosphere through small openings and through openings in a plug 134. The groove in the lower slide likewise connects externally through a duct 136. The vacuum enters by a duct 138<1> midway of the rod 122. If the preselector 150 is set to a new gear position, the button 138<2> moves down clear of a constricting collar 140 and pushes the slide 128 before it. When the vacuum is turned on, it is passed on through a duct 130 to the space below the piston 124. The piston 124 therefore follows the button downwards and stops with the button in the mid position shown. If the button be moved upwards, the slide 128<1> is lifted clear so that on release of the accelerator 30 the vacuum passes through another duct 132 in the thickness of the rod 122 to the space above the piston 124, which effects an upward follow-up stroke. A modification of this servomotor is described with reference to Fig. 4, not shown, in which the follow-up valve is arranged down in the motor cylinder, but is otherwise similar. A modification is described with reference to Fig. 6, not shown, in which the piston rod is in two telescoping parts the inner of which carries the control button and the outer the piston. In this form, if the power fails, the outer part can be moved forcibly from the inner part. The inner part is connected by rigid levers and links to the preselector 150 so that the bracket 120 can be moved and the gear changed directly and mechanically from the lever 150 without preselection. The engine clutch is thrown out against its springs by turning a shaft 48, Fig. 5, on a piston 54 in the clutch motor 52 being sucked downwardly. A check valve 60 in the end plate 58 permits free entry of air when the piston 54 is sucked downwardly when the accelerator 30, Fig. 1, is fully released. The cross bar 72 is connected by a Bowden wire 68 and a lever 66, Fig. 5, to a slide valve 64 in the end plate 58. Thus exhaust of air from the space above the piston 54, and therefore the speed of re-engagement of the engine clutch when the accelerator pedal 30 is depressed, is controlled according to the extent of depression of the accelerator, and therefore to the speed of the engine 20. If the clutch servomotor 52 fails, the clutch shaft 48 can be operated manually through a lever 82, Fig. 8, by depressing a section 34 of the floorboard against a spring 46. The main gear control Bowden wire 142, Fig. 1, is connected to a lever 146, Fig. 10, keyed to the shaft 148 of the preselector handle 150, which moves over a dial 152. To guard against inadvertent shifting into reverse, the arm 146 is pressed by a spring 154 so that two balls 156 fast upon it are pressed into the opposite pair of two series of rounded depressions 158, Fig. 13, on a disc 160. The depressions 158<1> corresponding to the neutral before the reverse, and to the reverse itself, are deeper than the others so that extra effort is needed to turn the handle 150 into reverse. In the complete installation shown in Fig. 2, the main change gearing in the casing 84 receives power from a propeller shaft 44, Fig. 1, and transmits it to the driving-shaft 106 of an auxiliary bevel two-speed gear controlled by a pair of clutches 218, 220 from a third servomotor 232, Fig. 1, as described in Specification 417,648. Differential free-wheel clutches for driving the road-wheel axles are shown at 280, Fig. 2, which are adapted to be locked out during reverse drive. They are slid towards one another by suitable levers 290, 292 when the piston 300 of a fourth servomotor 298 is sucked to the right of Fig. 2 against return springs 304 when vacuum is admitted by a valve 141, Fig. 1. When the movable gear 112, Fig. 2, of the main gearing is moved to engage a reversing idler 100, a lever 143, Fig. 1, is turned clockwise to move the valve 141 so that a duct 306<1> leading from the fourth servomotor 298 is connected to a duct 306 leading to the manifold 22 through a manually controlled valve 308. The valve 308 is shown connected to a handle throttle control rod 32 which, by reason of lost motion, acts successively to close the valve 308, then to prevent actuation of the clutch disengaging control valve 78 by preventing completion of the release movement of the accelerator pedal 30, and finally gradually to open the engine control throttle 24. Specification 416,407 also is referred to. The Specification as open to inspection under Sect. 91 comprises the subject-matter of Specification 417,648 which does not appear in the Specification as accepted.