STEUEREINRICHTUNG FUER EIN VON EINER ANTRIEBSMASCHINE ANGETRIEBENES WECHSELGETRIEBE, INSBESONDERE FUER KRAFTFAHRZEUGE

1427113 Change-speed gear GENERAL MOTOR CORP 13 June 1974 [30 July 1973] 26247/74 Heading F2D A control for a motor vehicle transmission driven by a two-spool gas turbine and comprising fluid-pressure-engaged ratio-establishing friction drive-engaging means, such as clutches 24, 26 and brakes 56, 60, one of which, brake 56, is engaged for reaction in both low and reverse under control of a manual ranging valve 88, engagement of the said one brake 56 is subject to a disconnect (i.e. a declutch) valve 254 loaded by throttle pressure 148, representing (inversely) engine power, which prevents engagement of the reaction brake 56 in any forward setting of the manual valve 88 when engine power is below a predetermined value, and also prevents its engagement in reverse setting when engine power is above a predetermined value. Gear arrangement.-A two-train Simpson planetary gear set provides two reduced ratios, direct drive and one reverse, established by the usual forward clutch 24, direct-reverse clutch 26, low-reverse brake 56 and intermediate brake 60. A fluid coupling 22 permanently connects an engine-driven gear-input shaft 18 to the forward input ring gear 34 and is used for starting, after which it becomes locked up by speed-responsive engagement of the forward clutch 24, although the fluid coupling may additionally be used for torque splitting in direct drive, depending on the engagement condition of the forward clutch 24. Reverse is always all mechanical through the clutch 26, and although the fluid coupling preferably remains filled, it may be emptied in reverse. Function summary.-Fluid pressures responsive to output speed and compressor discharge pressure actuate 1-2 and 2-3 shift signal valves 94, 96, controlling corresponding relay valves 212, 236, which establish shifts between all three forward ratios in DR3 setting of the manual valve, with third, and third-second suppressed in DR2 and DR1, unless excessive engine speed results. Regulated pressure is augmented in reverse, and establishment of reverse is inhibited during forward movement. The rate of pressure increase during shift is controlled by individual trimmer valves 320, 324, 326 of known type. Fluid pressure supply and regulation.- Pressure in a main 84, fed by a single pump 78 driven by the transmission input shaft 18, is regulated by a regulator valve 86, loaded in the upward, pressure-increase, direction by a spring 106, and downwards by pressure on differential areas from line 84, also r