Patent GB-888017-A (GB)
Title: Preselective electropneumatic equipment for gear changing
IPC: F16H61/02
Filed: 1958-05-08
Abstract: 888,017. Change-speed control. FABBRICA ITALIANA MAGNETI MARELLI S.p.A. May 8, 1958 [May 8, 1957], No. 14735/58. Class 80 (2). In a preselective electropneumatic gear shift for vehicles, of the kind wherein a rod a is shifted axially by a motor m to select amongst gear-shift rods S 1 , S 2 , S 3  and turned in either direction by a motor n to establish a selected ratio, three phases of shift sequence, viz., neutralizing, shift-rod selection and gear establishment, are controlled by a neutralizing solenoid valve A and solenoid valves B ... E, respectively controlled by depression of the main clutch pedal 23 and a gateguided manual pre-selector lever U, and the motors m, n act on the rod a through a lever g which is removably fixed to the said rod a at O, is connected at one end by a tongue-and-slot connection at f to a main piston 2 of the motor n and carries at the other end an earthing brush q. The gear shown provides four forward ratios and one reverse; smaller or greater number of ratios may be provided. The shift sequence is produced by the combined action of switch-contacts P 1 , P 2 , P 3  contacted by the brush q and B 1  ... E 1  controlled by the manual lever U. The shift lever g is always first moved by power to a central neutral position before selecting and establishing power is switched on. The rod a is centred to select the 3-4 shift rod by a spring W. The motor n is compound and has also subsidiary pistons 3, 4 slidable in cylinders d 1 , d 2 , the latter being disposed in the ends of the main piston 2 and interconnected by a pressure-balancing conduit z 2 . Feeding compressed air through a port 11 to the cylinders d 1 , d 2  forces the pistons 3, 4 to the ends of the motor n and neutralizes the gear by centring the piston 2 and connection f of the lever g. Feeding a port 12 or 13 respectively urges the piston 3 or 4 to bottom its corresponding cylinder and subsequently displace the piston 2 and the arm g in a direction h 1  or h 2  to rotate the arm a to establish a selected gear. The gate-guided preselector lever U is fast on an earthed rod 16 which carries an arm N 1 , rotatable and slidable with the rod 16, having a contact 17 to engage terminals B 1 , B 2 , C 1 , C 2 , or E 1 , and a pair of arms N 2 , N 3 , rotatable but not slidable with the rod 16, having a bridge y to connect terminals D 1  with B 3  or B 3  with C 3 , the said terminals B 1 , B 2  and C 1 , C 2  being permanently bridged. In operation, e.g. for change from first to second speed, the lever U is moved into second speed position to earth B 1  and bridge B 3 , D 1 . The main clutch pedal 23 is then depressed to close a switch 22 which energizes the valve A through a normally closed contact 33 of a relay R 1 , R 2 , thus feeding the port 11 through the conduit ta, centring the piston 2 and neutralizing the 1-2 shift-rod S 1 , whereupon the spring W returns the rod a to the central position, selecting the 3-4 shift-rod S 2 . This causes the lever g to close contacts q, P 2 , completing the first phase, and energizing the relay winding R 2  which breaks the contact 33 to de-energize the valve A, and closes a contact 34, to energize the valve B through lines lrb, lb and contact B 1 , thus feeding the motor m through a line tb to shift the rod a axially to select the 1-2 shift-rod S 1  thereby closing the contact q, P 1  (the contact 34 being held by the now-energized relay R 1 ) and completing the second phase. Consequently the valve D is energized through contact 34, lines lrb, l<SP>1</SP>b, contacts B 3 , y, D 1 , line ld, contacts D 3 , D 4 , lines lc, l<SP>11</SP>c, and contacts P 1 , q, to feed port 12 through line td and rotate the rod a in the direction r 2 , thus establishing second gear and completing the third and final phase. When the clutch is released, opening the switch 22, the relays, electrovalves, and pneumatic motors are all de-energized in preparation for the first phase of the next shift. The first speed and reverse gears are engaged in a similar manner to that described for the second speed shift; however, in a 3-4 or 4-3 shift there is no cross-shift second phase in view of an automatic cross-shift to the relevant position during the first phase, and the third phase earthing is directed through the line lc and the preselector terminals C 1 , C 2 .