TM 5-3805-262-34TRANSMISSION THEORY OF OPERATION (CONT)Oil Flow in Neutral. Oil flows from oil sump through suction screen to chargingpump. Charging pump sends oil through filter to transmission control valve. Oilenters transmission control valve at main pressure regulator. Oil flows throughorifice in spool of main pressure regulator. As pressure of oil increases, pressurepushes spool to the right which opens passage to charge torque converter. Spool thenmoves as necessary to keep main pressure between 135 to 170 psi.Pressure of oil used to charge torque converter is controlled by torque converterpressure regulator. This regulator keeps pressure in torque converter at approxi-mately 80 psi. Oil from torque converter flows through oil cooler to lubricationpressure regulator. Lubrication pressure regulator keeps pressure in lubricationsystem at 15 to 30 psi. Lubrication system lubricates and cools transmission parts.Oil flows from main pressure regulator through passages in transmission controlvalve to two orifices. Oil flows through one orifice into lubrication system. Oilflows through second orifice to clutch cutout valve and then to shifting spool.Oil enters detent area of shifting spool and flows to area near center of shiftingspool where oil is available for low clutch, high clutch, and for operation of trim-mer plug. With shifting spool in neutral, all clutch circuits are connected to oilsump.Trimmer plug controls main pressure as a clutch begins to engage. Normally, mainpressure holds trimmer plug to the left, compressing spring. While trimmer plug iscompressing spring, main pressure is kept near maximum pressure.4-88
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