"The 3-bladed propellers are Hamilton Standard, hydromatic, full feathering controllable pitch, constant speed. Toggle switches on the pilot's pedestal electrically control the governors which maintain the constant speed feature." (Pilot Training Manual for the Liberator B-24)
In this photo, the prop switches are aft of the 4 levers labeled SUPERCHARGER. The switches are spring loaded to the center position. Holding a switch forward drives the corresponding prop governor in the increase direction. At full increase a limit light comes on. These lights are immediately left of the supercharger knobs and directly below the vertical speed indicator.
B-24 cockpit
The same lights illuminate when the prop governors are at full decrease. When setting power for takeoff, the book warns, "Be sure to move toggle switches forward; governor lights will also come on when switches are moved back, and this would set the governor for full low rpm."
To synchronize the left engines, "Leave the No. 2 as it is. Note the rotating shadow across the top of No. 1 propeller. If the shadow is rotating away from you the propeller is too slow." Similarly, the copilot synchronizes the right wing engines. If there's still an engine beat or pulsation, the left and right wings are out of synch. Slightly increase or decrease rpm on one wing with a simultaneous flick of both switches, visually check that they're still in synch, and listen for a change in the pulsation. By this process you get all engines synchronized. At night you can use a flashlight or the reflection from the landing lights.
"When a propeller runs away, it simply means that the propeller governors fail to hold the propeller at its constant rpm setting. Thus, before takeoff when engines are idling, propeller is in low pitch (small bite), high rpm. Sudden application of power may cause a propeller to exceed the governor limit speed before the governor has a chance to take hold and increase the pitch. This is usually the case with a runaway propeller. However, if you have complete governor failure, you may not be able to regain control with throttle alone and will have to use the feathering button."
The first procedure is to reduce throttle and operate the prop switch in the decrease direction. If that's effective, cautiously increase both controls. If not, hold the feather button in. (The 4 buttons above the center windshield in the photo.) At 2500 rpm pull the button out to halt feathering. If rpm starts increasing, the governor has failed. Continue to push and pull the feather button until at sufficient altitude to feather completely.
"The most important fact to keep in mind about a runaway propeller is not to feather it until you have tried out the 2 procedures which should give you control." The book cites a case where a propeller ran away on takeoff with a combat load. "Without trying to bring the propeller under control he feathered immediately. He was unable to maintain altitude and the ship crashed shortly after takeoff. Proper procedure would have given 15 to 50% power on that engine."
The book says nothing about power management during formation flight.