Another way to look at it. It's a big syringe. Setting it up the first time You put 50+ lbs of air into the back side with the engine off and the valve open. That pushes the piston all the way down. Then you bleed the air pressure down to about 10lbs.
Now you have an empty syringe. When the engine starts up the engine oil pressure fills the syringe and pressurizes the air on the backside. The syringe is set to give the shot.
If the oil pressure drops Dr Air pressure give it a nice smooth shot of oil.
As soon as the oil pressure rises back up the syringe refills.
Don't get confused by the valve. It doesn't do squat while the car is running. It's only purpose is to trap oil in the syringe when you shut the motor off. You have to close it before the motor is off so it traps oil in the syringe.
The only reason to run a cable or electric valve is convenience. You don't have to get out of the car while it is still running to trap the oil in the Accusump.
Hope I made it more confusing.
That's a good analogy. There's a reason I'm not a teacher.