Patent GB-799937-A (GB)
Title: Improvements in or relating to automatic gear changing mechanism
IPC: F16H61/02
Filed: 1955-07-19
Abstract: 799,937. Change-speed and clutch control. REMAX, Ltd., and BELLOMO, A. July 19, 1955 [July 20, 1954], No. 20876/55. Class 80 (2). Means for controlling a change-speed gear and main clutch (neither shown) on a vehicle, is arranged between them and includes a planet gear 173 &c., Fig. 6, of which a first element is manually movable to disengage the clutch and engage a starting gear, during which time a second element of the planet gear is fixed, the second element being thereafter coupled to a power source to effect speed-responsive clutch engagement to start the vehicle and disengagement on slowing down, the main gear remaining engaged until manual movement of the first said planet element to neutralize the gear and re-engage the clutch. Function summary. A master manual control lever 161, Fig. 14, has three settings only (excluding neutral N). Movement from N to two of these, AF or AR, causes release of the main clutch and engages first speed (where synchronized, second otherwise) or reverse. Subsequent events are entirely automatic under control of an engine-driven governor 102, Fig. 7, subject to complex accelerator and service-brake loading, and acting through a reversible mechanical relay to engage the main clutch for starting and thereafter causing automatic up and down shift with coincidental release of the main clutch and its re-engagement synchronized by a differential gear operating on the engine throttle. The third setting of the master control lever 161, MP, re-engages the clutch manually after engaging reverse for parking and may cut out the engine ignition. Manual lock-in of any ratio at the time effective is provided, as may also be full manual operation of both clutch and gear shift by normal controls whilst the master lever 161 is set in neutral. Means for emergency return to neutral from any gear, after e.g. braking the vehicle and engine to a stop, are also provided. Selector system. Three selector-rods 16, 17, 18, Fig. 5, of a synchromesh planet or other four-speed and one reverse gear project forwards from the gear casing (not shown) into the control device where. they are operated by a single lever 23, Figs. 1 and 5, which is moved axially on a splined shaft 24 for selection and is turned with the shaft for gear establishment. For direct manual operation, where required, these two movements are performed respectively by turning a rockshaft 26 (cross shift), and the shaft 24 itself. For the starting and subsequent automatic shift they are performed by two cam-grooves 7, 8, Figs. 1 and 10, on a shiftcam-drum 10, the first, 7, producing gear establishment through a follower 27, bell-crank 28, Fig. 4, link 29 and arm 30 ; the second 8, cross shift through a follower 34, lever 33, link 32, arm 31, rockshaft 26 and arm 25, Fig. 1. The first starting steps of the shift-cam-drum 10 to F or R and the step to park position MP are performed manually, all others being automatic. The power shift of the cam-drum 10 is associated with the control of two disc-cams 5, 6, Figs. 1 and 6, coaxial with the drum and controlling the main clutch as follows. Clutch control. The clutch thrust block 36, Fig. 1, is operated through linkage, not shown, which may include an hydraulic or other servomotor by a shaft 37, Figs. 1 and 2, which may carry a manual pedal and is rocked through parallel linkage 38, 40 and cam follower 42, moved radially outwards in opposition to a spring 43 to disengage the clutch, by the two disc-cams 5, 6 and, during emergency neutralizing, by a ring 44. The disc-cam 5, which is connected to the first element of the planetary control gear above referred to, acts for manual operation to disengage the clutch during initial engagement of the starting gear by the master control lever 161, Fig. 14, and shift-cam-drum 10. The disc-cam 5, connected to the abovementioned second element of the planetary control gear is stationary during this manual operation but afterwards takes over for automatic operation, for which, during each complete shift step of the shift-cam-drum 10, or during its step from F and R positions, Fig. 10, to I or P for forward or reverse start, the automatic disc-cam 5 is driven one complete revolution through an engine-driven forward-reverse relay (described later), such action being determined by the planetary control gear, as follows. The planet gear comprises four unequal planets 173 ... 176, Fig. 6, fast on a common spindle carried by the automatic disc-cam 5 and meshing respectively suns 178, 172, 179, 180, which receive drive in two different manners according to whether the operation is manual or automatic. For manual operation (starting or parking only), turning movement of the master control lever 161, Fig. 14, from N to AF or AR for engaging first gear or reverse for starting, operates a rockshaft 12, carrying a toothed segment 167, Figs. 2 and 6, meshing teeth 168 on a larger toothed segment 169, meshing a toothed wheel 170 fast with the sun gear 172. A spring- loaded facially-toothed detent sleeve 206 locates and limits turning movement of the segment 169. The automatic disc-cam 5 remains held by its servo drive gear, thus stationing the planetcarrier so that the manual rotation of the sun 172 drives, in the same direction, the sun 178 which is fast with the manual disc-cam 6, which disengages the main clutch, and also the suns 179, 180, the former being selectively clutched to the shift-cam-drum 10 in reverse setting, the latter 180 in forward. Such selective clutching is effected, in neutral only, by a pawl 182 moved radially through a cam 13, rocked by axial movement of the master control lever 161, Fig. 14, in the gate slot 157 in passing between AF and AR positions. After disengagement of the clutch by the disc-cam 6, the shift-cam-drum is thus turned one step to engage the appropriate starting gear at F or R, Fig. 10. From this point onwards the re-engagement of the clutch for starting and subsequent shifts are entirely automatic, except for movement of the master control lever 161, Fig. 14, into the lower and longer gate slot MP, whereupon the manual cam 6 is taken a further step in the reverse direction and re-engages the main clutch at P for parking with reverse engaged. Clutch starting engagement. In positions AF or AR, accelerating the engine causes an engine-driven governor 102, Fig. 7 (subject to a complex loading system described later) to act through a lever 79 to slide a relay clutch sleeve 78, unlocked by the preceding manual movement of the shift-cam-drum 10 from N, to engage positive clutch teeth on one of two suns 74, 75, Fig. 6, continuously rotated in opposite directions by two planets on a toothed carrier 67 driven by a wheel 64 fast on an engine driven sleeve 63 (which by-passes the main clutch and its shaft 14), and carrying a further planet meshing a permanently fixed sun 69. The sun 75 provides the forward and reverse start step and subsequent upshifts, for leftward movements of the governor-controlled clutch 78, the sun 74 downshifts, for rightward movements on speed decrease. An asymmetrically apertured web 84, described later, ensures that the relay clutch sleeve 78 is disengaged on completion of one revolution, which it must complete, such revolution, through a toothed wheel 83, driving the automatic disc-cam 5 through an equal revolution, during which the automatic disccam 5 acts as a driving planet-carrier whilst the sun 172 of the planetary control gear is held by the detent sleeve 206. Of the remaining three suns that, 178, fast with the manual disc-cam 6 rapidly turns the latter out of its position maintaining clutch disengagement into free positions which it continues to occupy when stepped further during all remaining shift cycles. This permits the single revolution of the automatic disc-cam 5 to engage the main clutch for starting the vehicle. At the same time that one or other of the remaining suns 179 or 180 which has been clutched at 182 to the shift-cam-drum 10 in dependence on the AF or AR setting of the master control lever 161, Fig. 14. turns the shiftcam-drum 10 ineffectively through one step to position I or P, Fig. 10. The single revolution control of the relay clutch 78 is as follows. The clutch sleeve 78, Fig. 6, has an internal web 84 having an eccentric or asymmetrical opening which is just filled by a fixed disc 86 in the idle central position of the clutch-sleeve 78. After being moved axially in either direction to engage the relay clutch, the web 84 of the clutch sleeve lies to one or other side of the fixed disc and, once turning has begun cannot return to the central release position until a whole revolution has been completed. At this time the sleeve 78 is normally centralized by the governor 102, but it is also centrally loaded by a spring 87 acting through pins 100, 101 on a sleeve 88 and centrepin 90 carrying discs 89, 91 pressing inwardly on opposite sides of the web 84, the centre-pin 90 acting on its disc through a strong spring 96. The pins 100, 101 are secured to non-rotary rings 98, 99, which between them form a shaped slot receiving a pin 94 which is loaded leftwards by a strong spring 97 and is carried for rotation with, but axial movement relative to a toothed wheel 93, geared to the shift-cam-drum 10. The shape of the slotted rings 98, 99, Fig. 8, is such as to prevent relay clutch engagement in a direction tending to go beyond fourth speed and reverse settings; to lock against governor action in neutral, the springs 96, 97 being stronger than the governor; and also to disengage the relay clutch 78 after an emergency return of the shift-cam-drum to neutral by governor action (see below). The mechanical relay may operate at two different speed ratios, under accelerator control. Gear shift. The engine-driven governor 102, Fig. 7, initiates automatic upshift and downshift sequencies by engaging the relay clutch 78, Fig. 6, to drive the automa