FIRST SPEED FORWARDWhen the console selector lever is moved from theNEUTRAL position to the FIRST SPEED FORWARDposition, spool (14) for direction selection is moved to theFORWARD position. With spool (14) for directionselection in the FORWARD position, the passages forNo. 1 and No. 2 clutches are open to the reservoir. Thepressure oil for these clutches goes to the reservoir andneither is engaged.Also, with spool (14) for direction selection in theFORWARD position, the passages for the No. 6 clutchis open to the flow of oil. As the No. 6 clutch fills, thepressure of the oil in the system has a decrease.When the oil pressure has a decrease, the springforce on modulation relief valve (2) moves themodulation relief valve to the left against its slug. Whenthe modulation relief valve moves to the left, it stops theflow of oil from the passages for oil going to torqueconverter (4).An orifice in the passage to the left end of differentialand safety valve (6) controls the flow of oil from the leftend of the combination valve. This orifice keeps thecombination valve from being moved completely to theleft by the spring force during a normal shift sequence.This keeps the differential and safety valve from workingas a safety valve between shifts.When the No. 6 clutch is filled, the oil pump causesan increase in the pressure of the oil. Pressure oil goesthrough a passage and a drilled hole in modulation reliefvalve (2) to the left end of differential and safety valve(6). The pressure oil in the drilled hole in modulationrelief valve (2) also opens its poppet valve and worksbetween the slug and the modulation relief valve.As PI pressure oil has an increase, differential andsafety valve (6) is moved to the right. The passage tothe reservoir that stopped the movement of thedifferential and safety valve in NEUTRAL now has PIpressure oil. This valve moves to the right until theorifices in the valve are open to the P I1 pressure oil fromselector valve (19). The orifices control the flow of oil tothe No. 3 clutch. When the No. 3 clutch is filled, the P2pressure oil plus the spring force move differential andsafety valve (6) to the left to stop the flow of oil throughthe orifices. Now PI pressure has an increase.As the P1 pressure oil has an increase, the PIpressure between the slug and modulation relief valve(2) moves the modulation relief valve to the right. Whenthe modulation relief valve moves to the right, it connectsthe passages to let pressure oil go to torque converter(4). PI pressure also goes through the orifice to the rightof load piston (3). The P1 pressure on the load piston,plus the spring force, makes modulation relief valve (2)move to the left. When the modulation relief valvemoves to the left, it stops the flow of oil to the passagesto torque converter (4) and PI pressure has an increase.As PI pressure becomes higher, the modulation reliefvalve moves to the right again and opens the passagesto the torque converter. This higher P1 pressure alsogoes through the orifice to the right of load piston (3).The higher PI pressure on the load piston, plus thespring force, makes the modulation relief valve move tothe right again and again until the PI pressure is at amaximum. The modulation relief valve controls themaximum pressure by letting the extra pressure go tothe passage for the torque converter. This gradualincrease in pressure is modulation. The modulationrelief valve (2) gives modulation for all the clutches(speed and direction).The differential and safety valve (6) causes aconstant pressure difference of 50 psi (3.5 kg/cm2) (344kPa) less than the PI pressure to the speed clutches.This pressure difference lets the speed clutches becomeengaged first, and then the direction clutches areengaged last. When the PI pressure is at a maximum ofapproximately 3 10 psi (21.80 kg/cm2) (2137 kPa), theP2 pressure is at approximately 160 psi ( 11.25 kg/cm2)(1103 kPa). The shift is now complete.The inlet ratio valve (5) controls the maximum oilpressure to the torque converter. P1 pressure betweenthe ratio valve and its slug keeps the valve closed. Thepressure of the oil that goes through the passage to thetorque converter is felt by the end of the ratio valveopposite the slug. When the pressure of the oil to thetorque converter is less than 1 15 psi (8.08 kg/cm2) (793kPa), the ratio valve closes and the pressure oil goes tothe torque converter.2-95
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business