[rotorwrench]

Pulling the OD cable locks out the overdrive actuator pawl and moves the sun gear to disengage the planetary gears. The early 1951 may still have an electrical lock out switch that opens the circuit between the governor and the relay to keep the operating solenoid from activating. Ford did away with this feature in 1951 so it may not have that switch. They felt it was redundant but I like having that switch just to save on electrical power above on speed of the governor which is around 25 MPH.

The most importance caution with the R10 overdrive is when you park the car on a hill. Either pull out the lock out cable or put the transmission in reverse gear. If the E-brake is a little loose, the car WILL roll down the hill. MY oldest brother found that out the hard way. He pulled a small grain cart into a local grain elevator to fill it with feed grain for his hogs. He disconnected the trailer to fill it and pulled the old 51 Mercury out the door. He shut it off and put it in gear but not in reverse. As he walked back into the elevator door, the old Merc rolled down the ramp of the grain elevator, across the street, and ran into a brand new car parked on the other side. My brother never made too many mistakes in his life so that was his worst. My Pop pulled the cable out and had the cable assembly removed from the dash and wired up underneath. That was the last time my brother ever used the overdrive on that car.