TM-9-2520-234-35 Technical Manual for M109 Transmission XTG-411-2A Download

CHAP 2, SEC IV DESCRIPTION AND OPERATION OF PAR 30 RIGHT- AND LEFT-OUTPUT DRIVE ASSEMBLIES TV pressure at this time is at maximum and can flow into the T pressure line. T pressure is connected to the area below the lockup shift valve, as is TV pressure. The effect of T pressure is to delay the downward movement of the lockup shift valve. Thus, at full throttle, governor (pitot) pressure must be higher to cause lockup. Higher governor pressure requires higher turbine shaft speed. i. The main pressure line entering the throttle valve bore at the right has no function. j. At the steer pressure regulator valve, main pressure is reduced and regu- lated, and produces steer pressure. Note: The pressure which applies the output clutches, geared steer clutches and brakes — whether for steer operation or straight travel — is always designated "steer pressure ." Steer pressure is constant, regardless of fluctuations in main pressure. k. Steer pressure is directed to the steer valves. In neutral, it simply flows through passages surrounding the steer valves, and is directed by two drive clutch feed lines to the drive clutch relay valve. The drive clutch relay valve, held upward by signal pressure, directs steer pressure to the right- and left-geared steer clutches, These clutches are the drive clutches in first gear. Thus, in neutral, they are engaged and ready to transmit drive when a shift is made to first gear. 1. Governor (pitot) pressure is pro- duced in a fluid velocity-type governor. This consists of only two main compo- nents: a governor ring and a pitot tube. The ring is a rotating channel, open at its inner circumference. It is attached to the high-range clutch housing and rotates with the turbine output shaft. Oil is constantly fed to it from the lubrication system and centrifugal force retains the oil. Tine pitot tube is L-shaped and its open end is im- mersed in the oil in the governor ring. The open end of the tube faces against the rotation of the ring. The oil, moving at virtually the same speed as the ring, is thrown into the pitot tube and is directed to the top of the lockup shift valve, the left end of the shift inhibitor valve, and to the area between the lands of the lock-up cutoff valve. Governor pressure varies with the speed of the turbine output shaft. m. At the top of the lockup shift valve, governor pressure pushes downward on the valve. At closed throttle condition, pressure sufficient to overcome only the lockup shift valve spring will force the valve downward. At part throttle condi- tion, spring pressure plus TV pressure (initially) must be overcome. At full throttle condition, spring pressure plus maximum TV pressure and T pressure must be overcome. n. At the shift inhibitor valve, gov- ernor pressure pushes the valve toward the right. A spring resists this movement. When governor pressure is sufficient, the right end of the inhibitor plunger will be pushed against the longest projection on the manual selector valve lever. In neu- tral, this is not significant. o. At the lockup cutoff valve, gover- nor pressure is blocked except for brief intervals during shifting. When shifts are made, the lockup cutoff valve moves rapidly to the left and exhausts governor pressure to the sump. This destroys gover- nor pressure and allows the lockup shift valve, if downward, to move upward and release the lockup clutch. This feature ensures that the lockup clutch will be re- leased every time a range clutch engages. p. Oil returning from the torque con- verter passes through an (external) oil cooler and flows into the area above the 28 Change 2