The 1-2 and 2-3 shift valves are control valves which are supplied with line pressure from the manual valve.
Which either block fluid or allow it to flow at prevailing line pressure to a clutch or band servo.
Their position and movement is determined by a spring plus T.V. pressure acting at one end, opposed by governor pressure acting at the other end.
This valve is mounted on and rotates with the transmission output shaft. It re-regulates line pressure supplied to it from the manual valve, in relation to vehicle speed.
When vehicle speed is low, governor pressure is low.
When vehicle speed is high, governor pressure is high. Governor pressure is directed to the end of the shift valve to oppose T.V. and spring pressure and this produces upshifts relative to vehicle speed.
This valve is included in the throttle valve combination. When the accelerator is depressed fully, the downshift valve supplies line pressure on to the spring end of the shift valve. If road speed is below a certain value, this forces the shift valve to move and initiate a downshift to a lower gear.
This valve is in the circuit to the release side of the front band servo. It is a timing device which correlates the release of the front band and the application of the rear clutch when a 2-3 upshift is made at higher road speeds. Conversely it correlates the release of the rear clutch and the re-application of the rear band when a 3-2 downshift is made under similar conditions.
This valve is provided to make line pressure and throttle pressure sensitive to road speed and ensures these pressures are cut-back at higher road speeds to allow smooth upshifts to take place. It also moderates the increase in line pressure produced by wide throttle openings during stall or upshift conditions.
The high throttle pressures produced at these times raises line pressure to a very high value since the throttle pressure is applied to the spring end of the primary regulating valve.
Modulator pressure is applied to the opposite end of the regulating valve to counteract this and moderate its influence.
