Improvements in or relating to variable speed driving mechanisms

摘要

826,952. Change-speed and clutch control. FICHTEL & SACHS A.G. Feb. 6, 1956 [Feb. 10, 1955], No. 3620/56. Class 80 (2). In coincidental fluid-pressure clutch and gear-shift actuation, a manual selector lever 27, or push-buttons, operate one or more ratioshift levers 19 only after the main clutch lever 13 has been moved to disengage position, the clutch being allowed subsequently to reengage only after gear-shift pressure has exceeded a predetermined minimum necessary for gear-shift. The shift levers 19 are operated by compressed air motors 21 energized by selectively supplying lines 22, 23, 24 through a distributer valve 25 operated by the manual lever 27 and fed from a line 26 which is opened to the pressure side of a clutch motor 16 only when a piston 15 therein has moved the clutch lever 13 to clutch-release position, or directly pressurized by the clutch-lever 13 mechanically, electrically, or by fluid-pressure opening a valve connecting the line 26 to the pressure source. In operation, after pre-selecting a ratio by the manual lever 27 or push-button, a push-button of a switch 29 is depressed by hand, foot or by the shift-lever 27 or shiftbutton itself, to energize a solenoid valve 18 supplying compressed air to the clutch-motor 16 which, after disengaging the clutch, feeds the distributer valve 25 as above described, for gear shift. Automatic release of the pushbutton 40, Fig. 4, of the switch 29, Fig. 1, for clutch re-engagement is provided by a latch 45 which holds the button 40 in the depressed position and is released automatically after a predetermined time by a diaphragm 48, energized through a restrictor by the gear shift air-pressure 28, but only when said pressure exceeds (by 50%) the pressure necessary to actuate the shift mechanism. Where a separate clutch-controlled valve is used to supply the gear shift line 26, such valve may also be similarly opened only by clutch pressure building up to a value greater than that required for declutching. The transmission may include a hydrodynamic coupling or the main clutch may be a disengageable centrifugal one.