Patent GB-911039-A (GB)
Title: A gear-changing device with preselector
IPC: B62M25/00
Filed: 1960-03-25
Abstract: 911,039. Change-speed control. ZAVODY 9. KVETNA, NARODNI PODNIK. March 25, 1960 [April 6, 1959], No. 10664/60. Addition to 878,078. Class 80 (2). In the preselective change-speed control of the parent Specification, for single-track and other motor vehicles, wherein profile members 1, 2 which are together slidably keyed or splined on a shaft 4 arranged transversely of shift fork guide rails 17, 16 and each of which comprises cam-slots formed in the wall of a sectoral, or as shown, complete cylinder or multi-sided prism, are rotated for ratio preselection and axially displaced for gear establishment, the cam-slots acting directly on shiftfork pegs 13, 12, the shaft 4 is rotated, through a pinion 5, automatically by a centrifugal governor 21 responsive to vehicle speed for forward speeds, and manually by a control lever 33 for neutral (N), reverse if provided, and, for engine-braking, a forward gear (III, II or I) lower than that automatically preselected. The governor 21 may be mounted on a rack 6 and driven from a gear-box shaft 37 carrying a vehicle wheel driving sprocket 46, or, as shown, be mounted on the shaft 37 and, with the manual control lever in position " J," act on the pinion 5 through a sleeve 20 acting directly, or indirectly through a lever, and a gear sector or, as shown, through the sleeve 20, a lever 18, a further sleeve 22, a spring 25 and the rack 6. The force of the spring 25 is greater than the frictional resistance of the rack-and-pinion 6, 5 and the shaft 4 but is less than axial governor force. The manual control lever 33 acts on the rack 6 through a wire, pull rod, or, as shown, a cable 32, a bell-crank lever 31 and a wire, pullrod or, as shown, a cable 28 the nipple of which is enclosed in a cavity of the rack and acts on an end-plate 30. The members 1, 2 are axially displaced against a return spring 11 by a pedal executive lever 10 through a shaft 9 and levers 8. Since the position of the governor sleeve 20 is continuously variable, means is provided for locating the members 1, 2 in their accurate ratio positions, such means comprising radial pegs fast with the members 1, 2 engaging a fixed gate (Fig. 8, not shown) or, as shown, a locating member 38 fast with the members 1, 2 engaging a fixed peg 42. The locating member 38 comprises slots 39 having two sections : one, the lower, formed by divergent cam walls for circumferential location of the members 1, 2 during their axial displacement prior to gear establishment, and the other formed by parallel walls accommodating the fixed peg 42. To avoid impact of the fixed peg 42 and the meeting- points of adjacent divergent cam walls, a spring- loaded ball detent 45 in the sleeve 20 snaps into notches 44 arranged in pairs on the shaft 37 one on each side of each ratio changing position. Whilst the circumferential displacements of the cam-slots in the members 1, 2 and the slots 39 are equal, their phasing may be coincident or staggered. The speed ranges for each gear ratio are within those ranges providing optimum tractive force at the driving wheels, and may be determined by choice of stiffness or by prestressing of the governor return spring. The governor may be enclosed by rotating and fixed' casings 47, 48.