Patent GB-1268847-A (GB)
Title: Improvements in or relating to change-speed gears for motor vehicles
IPC: F16H63/36
Filed: 1969-07-10
Abstract: 1,268,847. Change-speed gear. ZAHNRADFABRIK FRIEDRICHSHAFEN A.G. 10 July, 1969 [24 July, 1968], No. 34854/69. Heading F2D.  Shift-forks 20, 27, 30 of double dog clutches 10, 13, 18 of three (or four) countershaft geargroups A, B, C, providing eight ratios (seven reduced, one direct) between input and output shafts 1, 2, on a motor-vehicle, are interlocked to operate in a predetermined sequence during multiple shifts by a pair of interlock levers 66, 74 which swing on fixed pivots 65, 75, and have locking recesses 67 &c. receiving rollers 59, 60, 61 on arms 50, 51, 52 extending from the shiftforks 20, 27, 30. The first shift-fork 20 is actuated directly mechanically as shown, or by power, by longitudinal movement of a manual shift lever 25 (direction X), mounted on a ball pivot 32, through axial movement of a rod 21, whilst the second shiftfork 27 is actuated by a double-acting fluid servo 28, energized by transverse, cross-shift, movement of the manual lever 25 (direction WZ), acting by turning the rod 21 to shift the pivot pin 19 of the first fork 20 axially to operate a change-over valve 39, this movement being produced by use of a connecting rod 36 anchored to the casing, as described in Specification 1,013,657. The third shift-fork 30 is actuated by a double-acting fluid servo 31 controlled by a valve 40, actuated by an independent lever 40a on the manual shift lever 25. Ratios one to four are all obtained with the rear clutch 18 in its forward (left) position and the manual shift lever 25 moved in a normal 1<SP>1</SP>, 2<SP>1</SP>, 3<SP>1</SP>, 4<SP>1</SP> H pattern, whilst for ratios five to eight, the valve lever 40a is raised to shift the rear clutch 18 to its rearward high position, and the H pattern repeated for 5<SP>1</SP>, 6<SP>1</SP>, 7<SP>1</SP>, 8<SP>1</SP>. Sequencing is required for shifts involving change-over of more than one clutch; e.g. 2-3 and 6-7, shifting clutches 10, 13; and 4-5, shifting clutches 10, 13 and 18. Taking 2-3 shift as example, initially both shiftforks 20, 27 are in their rightward position (Fig. 2). Movement of the manual shift-lever 25 to neutral first neutralizes the front clutch 10, so that its shift fork roller 59 reaches a neutral recess 68 in the interlock lever 66. Cross-shift movement of the manual lever 25 now energizes the second clutch servo 28 for leftward movement of the shift-fork 27, the roller 60 of which rides out of the recess 71 up on to a flat 78 of the interlock lever 66, thus locking the first shift-fork 20 in neutral, until the second fork 27 completes its forward engaging travel and its roller 60 drops into a lever recess 70, thus freeing the first shift-fork 20 for completion of its forward movement to an end-recess 67. For the all-change 4-5 shift, the position is initially as shown in Fig. 2. First action is to raise the shift-valve lever 40a to S position, energizing the rear servo 31 to tend to shift the rear fork 30 right, which at this time it is unable to do because its roller 61 is locked in the recess 76 of the interlock lever 74, which is prevented from pivoting clockwise by the roller 60 of the second shift fork 27. The manual shift lever 25 is now moved to neutral, taking the first shiftfork roller 59 into the recess 68, which permits the interlock lever 66 to pivot clockwise, releasing the roller 60 of the second shift-fork 27, which, during the subsequent cross-shift movement of the manual lever 25 is moved by its servo 28 as far as the neutral recess 72 in the lever 74, which prevents its further movement, thus neutralizing movement also locking the first fork 20 in neutral by its lever recess 68. The interlock lever 74 is now free to pivot anticlockwise sufficiently to allow the roller 64 of the third shift-fork 30 to ride over the flat 79 into the recess 77, completing shift of the rear fork 30, which movement frees the second fork 30 for completion of its movement to the recess 71, which finally frees the front shift-fork 20 for movement to the recess 67, thus completing the shift. The object of the three-two-one engaging sequence is to obtain minimum inertia forces on accelerating clutch-members during the shift. A low-speed and reverse group D, not described, precedes the gear.