Patent GB-709501-A (GB)
Title: Improvements in or relating to change speed gears for motor cars
Inventor: SGUAZZI ANGELO
IPC: F16H61/02
Filed: 1952-06-09
Abstract: 709,501. Change-speed gearing. F.R.A.M. FABBRICA DI MOLLE ED ACCESSORI PER ROTABILLI. June 9, 1952, No. 14531/52. Class 80 (2) In motor-vehicle changespeed gearing with automatic pre-selection by output speed and an executive member co-operating with the clutch control, means are provided whereby, except in the case of the lowest and highest speeds, the same gear cannot be engaged by successive operaations of the executive member but on the second operation the next higher or lower gear is engaged. In the four-speed and reverse gear shown, a cross shaft 21 is moved axially according to output speed through levers and links 14, 17, 18 by a centrifugal governor 6 on the output shaft 3, and is adapted to be rotated, against the action of a return spring 66, by a sleeve 26 splined thereto and constituting the executive member. Projections 31, 32, 64 on the shift rod A for first and second gears and projections 37, 38, 39, 40 on the shift rod B for third and fourth gears co-operate with arms 22a, 22b, 23, 24 on shaft 21. to disengage and engage appropriate gears as the shaft is rotated clockwise (in Figs. 6; 7). Knife-shaped stationary ribs 53a, 53b, 53c'serve to guide the knife-shaped end 22c of arm 22a into slots 50, 51, 52 corresponding to first, second and third gears. A lever 56 pivoted freely in slot 51 has a knife-shaped end 56a normally held raised by abutment of the other arm 56b against a spindle 55. A lever 57 pivoted freely in slot 52 has a knife-shaped end 57a normally held raised, its other arm carrying a spring blade 61. A cross shaft 42 below shaft 21 is adapted to be turned in one or other direction through levers and limbs 43, 44, 45, 46 by a lever L on the steering column. Fig. 2 shows the position with first gear engaged, this being effected at starting by moving lever L to its forward position, whereby shaft 24 is turned clockwise (in Fig. 4) so that an arm 48 thereon acts on a pawl 34 on rod A to move the latter to the right to engage first gear, the shaft 24 thereafter remaining in this position with the pawl 34 riding over the arm 48 during subsequent gear changes. When second gear is engaged, a part 31a of the projection 31 acts on an arm of spindle 55 to turn the latter clockwise (in Fig. 6) whereby a recess 55a allows the end 56a of lever 56 to fall, so that if shaft 21 is again rotated while second speed is still pre-selected, causing second gear to be disengaged, the end 22c cannot again enter slot 51 to allow secured gear to be re-engaged but the co-operating knife edges cause the shaft 21 to move down or un, depending on whether the output speed is slightly lower or higher, to engage first or third gear. Similarly, when third gear is engaged, the projection 37 acts on spring 61 to depress the end 57a to prevent re-engagement of third gear on the next operation. A spring acting on the lever 18 is connected to the accelerator so that if the latter is kept depressed during a gear change the spring is tensioned to impose an additional restraint to axial movement of shaft 21 and so vary the pre-selection speed values. A projection 97 on rod A co-acts with arm 23 to prevent shaft 21 from moving beyond second gear position when first gear is engaged, so that the gear cannot be changed directly from first to third. Reverse 'is engaged by moving lever L to reverse position, thereby turning shaft 42 anti-clockwise (in Fig. 4). During the first part of this movement, an arm 47 on shaft 42 engages a projection on shaft 21 to turn the latter clockwise thereby disengaging second, third, or fourth gear if engaged, while if first gear is engaged it is disengaged by arm 48 engaging a projection 33 on rod A..During the final part of the movement, a pin 68 on arm 47 engages a recess 67 in the reverse shift rod C to engage reverse gear, this final movement being possible only when the output speed is low enough to allow a part 41 of arm 47 to engage a slot 65 in shaft 21. Shaft 21 may be rotated by depression of the clutch pedal, linked to an arm 86 on the shaft, the clutch control linkage including a hydraulic servo motor if desired. As shown in Fig. 15, a pedal S operates a valve 75 controlling flow of pressure oil to a cylinder 77 containing a piston which controls the sleeve 26 and also controls a lever for operating the clutch or the switch of an electromagnetic clutch. In engaging reverse, a cam projection 90 on arm 43 operates valve 75 through a strut 91 to temporarily release the clutch before rod C is shifted. Alternatively, the clutch pedal may operate a similar valve. Signal lamps in a housing 92 on the steering column indicate which gear is engaged.