D-4 - Overdrive

With 4L60 (700-R4) Transmissions - 4WD Shown, 2WD Similar:

D-4 - OVERDRIVE

CONVERTER CLUTCH - APPLIED
3-4 CLUTCH - APPLIED
2-4 BAND - APPLIED
FORWARD CLUTCH - APPLIED
FORWARD SPRAG CLUTCH - NOT HOLDING

As both vehicle speed and governor pressure increase, the force of governor oil acting on the 3-4 shift valve overcomes the force of the 3-4 Throttle Valve (T.V.) spring and Modulated Throttle Valve (M.T.V.) up oil. This opens the 3-4 shift valve sending Drive 4 (D4) into the fourth signal passage. Fourth signal oil will overcome the 4-3 sequence valve spring and open the 3-4 relay and the 4-3 sequence valves, allowing second oil to enter the servo feed passage.

Servo feed oil is directed to the following:

1. 2-3 Shift Valve
a. Which directs oil to the:
1) 3-4 Accumulator
2) 4-3 Sequence Valve

2. 4-3 Sequence Valve
a. Which directs oil to the:
1) 4th Apply Piston (in the 2-4 servo)

BASIC CONTROL

Servo feed oil passes through the 4-3 sequence valve and becomes fourth oil. Fourth oil then enters the 2-4 servo, applies pressure on the fourth apply piston, and applies the 2-4 band.

SUMMARY

The converter clutch*, 2-4 band, forward clutch, the 3-4 clutch are applied, and the forward sprag clutch is overrunning; the transmission is in Drive (D) Range - Overdrive.

*The converter clutch may or may not be applied, depending on solenoid operation.