D-4 - Second Gear

D4 - Second Gear:

D-4-SECOND GEAR

2-4 BAND - APPLIED
FORWARD SPRAG CLUTCH - HOLDING
FORWARD CLUTCH - APPLIED

As both vehicle speed and governor pressure increase, the force of the governor oil acting on the 1-2 shift valve overcomes the pressure of Modulated Throttle Valve (M.T.V.) up oil and the force of the 1-2 throttle valve spring. This allows the 1-2 shift valve to open and Drive 4 (D4) oil to enter the second (2nd) oil passage. This oil is called second (2nd) oil. Second oil from the 1-2 shift valve is directed to the following:
1. 1-2 Shift Checkball (8)
2. 2-4 Servo
3. 1-2 Accumulator Piston
4. Solenoid Assembly (Converter Clutch)
5. 3-4 Relay Valve

BASIC CONTROL

Second oil from the 1-2 shift valve will seat the 1-2 shift checkball (8) forcing 2nd oil through an orifice. Second oil is then directed to the 2-4 servo to apply the 2-4 band. At the same time, 2nd oil moves the 1-2 accumulator piston against accumulator pressure and the accumulator spring to maintain a controlled build-up of pressure on the servo during the 1-2 shift for a smooth band apply. 2nd oil at the 3-4 relay valve is available for use in other ranges.

Second oil is rerouted into converter clutch signal oil above the 1-2 shift valve. Converter signal oil exhausts at this solenoid until a signal is received from the vehicles E.C.M.

SUMMARY

The converter clutch is released, the 2-4 band is applied, the forward clutch is applied, and the forward sprag clutch is holding; the transmission is in Drive (D) Range - Second Gear.