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307-01-35 Automatic Transmission 307-01-35 DESCRIPTION AND OPERATION (Continued) 4-3 Sequence Valve 2-3 Shift Valve This valve switches during 3-4 and 4-3 gearshifts 3-4 Shift Valve although it performs no function during the 3-4 shift. It’s sole purpose during the 4-3 shift is to delay the This valve is used for 3-4 and 4-3 shifts. Switching of connection of the clutch apply feed circuit (CAF) to the this valve is done directly by solenoid 1 which is B1R circuit until the B1R circuit has been fully located at the end of the valve. The function of the pressurised by using the 3rd circuit. It prevents valve during a 3-4 shift is as follows: objectionable engine flare at the completion of the 4-3 3-4 Shift Valve gearshift. B1R Exhaust Valve exhausts the front band release circuit (B1R) thereby allowing the application of the band. This valve is located in the case directly adjacent to (B1AI) to the band apply feed circuit (BAF) thus the front servo. Its function is to allow the servo allowing greater apply forces to the front band. release oil to be rapidly exhausted into the transmission case during application of the front band exhausts the overrun clutch circuit (O.C.) which rather than forcing the oil back into the valve body will allow the C4 clutch to release. and through the 3-4 shift valve. In addition the spring The exact opposite of the above functions will occur on one end prevents oil entering the release area of on a 4-3 downshift. This valve also switches during the servo until the circuit pressure reaches Manual 1st-2 and 2-Manual 1st gearshifts where it’s approximately 70 kPa. function is to apply the overrun clutch (C4) in 2nd This valve also ensures that C1 pressure has reached gear but to release it in Manual 1st gear. Note that the 70 kPa on a 2-3 shift before B1 is allowed to begin C4 clutch is applied in Manual 1st by the 1-2 shift releasing, thus preventing unwanted engine flare at valve. the commencement of the gearshift. G73081 en |