Patent GB-781409-A (GB)
Title: Improvements relating to gear shift mechanism for vehicular transmissions
Inventor: QUAYLE GEORGE FRANCIS
IPC: F16H59/04
Filed: 1955-11-07
Abstract: 781,409. Controlling change-speed gearing. YALE & TOWNE MANUFACTURING CO. Nov. 7, 1955, No. 31742/55. Class 80 (2). Gear shifting mechanism, particularly for industrial trucks, comprises a pair of shifter rods 11, 12 each movable from a neutral position in opposite directions to two gear engaged positions, and means 36, 38, &c., for preventing movement of both the shifter rods in one or other of the two opposite directions from the neutral position, a common control means 20 &c. enabling either of the shifter rods to be moved in the direction in which it is free. Movement of the shift rod 11 left or right from the neutral position shown in Fig. 3 engages a high- and a low-ratio in reverse, and similar movement of the shift rod 12 engages a high- and a low-ratio for forward movement. The control means comprises an actuating rod 17, Figs. 1, 3 and 6, axially and pivotally movable in a housing 16, and carrying rigidly a plate 21 with slots 22, 23 at its opposite ends. The slots 22, 23 respectively are selectively engaged with pegs 25, 24 on a control plate 20 pivoted at 19. The pegs 24, 25 lie in different planes, and engagement of the slots 22, 23 therewith is selected by axial movement of the rod 17 and plate 21. The control plate 20 has a downwardly extending post 26 engaged in the bifurcated end 28 of a plate 29. Shifter elements 13, 14 on the shift rods 11, 12 are provided with upwardly extending pins 31 engaging in a pair of slots 30 in the plate 29. Thus turning movement of the rod 17 etc; will cause turning movement of the plate 21 and the plate 20, and sliding movement of the shifter elements 13, 14. To enable the plate 29 to fulcrum about one of the pins 31, movement of the shifter elements 13, 14 either left or right of Fig. 3 is prevented by blocking means. This comprises a cam member 34 on a rotatable shaft 35. Cams 36 at the end of the cam member are positioned to coact with either of spaced vertical surfaces 37, 38 formed integrally on each shifter element 13, 14. The vertical surfaces 37, 38 are so spaced relatively to one another that each shifter element 13, 14 can move with its rod 11, 12 relatively to the cam 36. With the cams 36 coacting either with the surfaces 37 or with the surfaces 38, depending upon the rotative positions of the cams, the movement of the shifter elements in one direction or the other away from the neutral position is blocked. Accordingly the fulcruming action of the plate 29 is controlled. With the parts in the position shown in Fig. 1, when the cam 36 co-operates with the surfaces 38, the shifter elements 13, 14 can move only to the right. If the plate 29 is now moved from the neutral position shown in Fig. 3 in a counterclockwise direction, the forward shift element 14 is fixed and it accepts the reaction of the plate 29, so that the rearward shifter element 13 moves to the right to lowspeed position. If the plate 29 moves in a clockwise direction, the rearward shift element 13 accepts the reaction of the plate, and the forward element 14 moves towards the right to the low-speed position. Thus, with the parts in the position shown in Fig. 1, when the slot 23 on the plate 21 engages the post 24 on the control plate 20, rotation of the plate 20 engages only the low forward and reverse ratios. If the cam unit 34 is rotated so that the cam 38 now engage the surfaces 37, and the shifter element 13, 14 can accordingly be moved only to the left, then only the high-speed forward and reverse ratios can be engaged. So that the shaft 17 &c. shall be turned in the same direction for forward and reverse directions of motion both between the low ratios and the high ratios, a cam 39 on the cam unit 34 engages between the horizontal arms of a U- shaped bracket 40 on the downwardly extending part 41 of the actuator shaft 17. Turning the cam member 34 from the position shown in Fig. 1 thus raises the shaft 17 to disengage the slot 23 in the plate 21 from the peg 24, and simultaneously engage the slot 22 therein with the peg 25 or the plate 20. Thus, clockwise rotation of the plate 21 now causes anti-clockwise rotation of the plate 20, as shown in Fig. 5. The cam unit 34 and the actuator shaft 17 are controlled from a steering column shifter handle 45, Fig. 9. Turning the handle 45 pivots a rod 44 and, through links 52, 57, 55, turns the shaft 17 to engage forward or reverse drives. Up and down movement of the handle 45 relatively to its steering column is permitted only when the gear is in its neutral position, when a cross pin 46, Fig. 8, on the rod 44 can slide through a gap in a supporting bracket 43. Up and down movement of the handle 45 and the rod 44 pivots a link 58, Fig. 9, connected through links &c. 60, 61 to the shaft 35 and cam 34, to select either the high, forward and reverse, or the low forward and reverse ratios,