Part Throttle 4-3 Modulated Downshift Valves In 3RD Gear

A part throttle 4-3 downshift can be accomplished by depressing the accelerator pedal enough to move the throttle valve (T.V.) plunger, which then permits T.V. oil to enter the part throttle passage. This part throttle oil is then routed to the 3-4 throttle valve. Part throttle oil, in combination with 3-4 spring pressure, forces the 3-4 shift valve against governor oil and prevents RND4 oil from entering the 4th clutch passage. Exhausted 4th clutch and 4th accumulator oil then passes through the 3-4 shift valve to the 4-3 control valve, which releases the 4th clutch and ensures a smooth 4-3 shift.

A modulated downshift can be obtained in some ranges by depressing the accelerator pedal enough to raise M.T.V. down pressure. This pressure, when combined with the throttle valve spring tension, can overcome governor pressure and cause a downshift to occur.