GB1013929A - Improvements in or relating to devices for controlling synchronised gear engagement in change-speed gear transmissions - Google Patents

Abstract

1,013,929. Change speed control. FABBRICA ITALIANA MAGNETI MARELLI S.p.A. May 8, 1962 [May 9, 1961], No. 17588/62. Heading F2D. [Also in Division H3] In a change speed gear control wherein, during ratio shift, establishment of a new ratio is prevented until synchronism is attained, the latter is detected by a transistorized comparitor circuit V 1 , V 2 which compares the voltages from an input driven generator G 1 and the appropriate tapping, corresponding to the selected ratio, of an output driven generator G 2 , and when the voltages are approximately equal the comparitor circuit triggers a transistorized control circuit V 3 , V 4 which operates a relay M that permits establishment of or establishes the selected ratio. As shown, the voltages from A.C. generator G 1 , G 2 are applied through rectifiers R, C 1 ; R, C 2 to the bases of transistors V 1 , V 2 which when the applied voltages are approximately equal (i.e. equivalent to within 10% of synchronism) produce maximum voltage at R 4 which causes transistor V, to become saturated and energize the relay M. When the applied voltages differ the appropriate transistor V 1 or V 2 becomes saturated and produces a voltage at R 4 which causes the transistor V 3 to cut-off and the transistor V 4 to become saturated whereupon the relay M is de-energized. A gear shift lever switch C selects the appropriate tapping of the generator G 2 . For starting in the lowest speed ratio or reverse a switch C<SP>1</SP> energizes the relay M directly from a battery N. By making suitable circuit modifications the generators may be replaced by D.C. generators. As shown, energization of the relay M moves right a sleeve 22 against the action of a spring 26 thus releasing a locking ball 18 from a groove 16 in a rod 10, axial movement of which latter establishes the gear ratio. In Figs. 6 and 7 (not shown) the relay operates a radially movable plunger which acts on the locking ball. As shown, a single locking device acts on a rod 10 between the gear shift lever 12 and selector rods 14 but individual locking devices may be provided for each selector rod (Fig. 3), not shown) in which case a further gear shift lever switch connects the control circuit to the appropriate locking device relay. The locking devices may be omitted in which case ratio shift is selected manually and established at synchronism by pneumatic servos energized through solenoid valves which are selectively connected to the control circuit by a gear shift lever switch (Fig. 9, not shown). Reference has been directed by the Comptroller to Specification 854,031.