Once you drill a hole to the oil,
ya gotta get it up where you can use it.
These things spin 24 hours a day.
The "sucker rod" (the part that looks like it comes out of the horses head)
mover up and down,sucking out a little oil at a time.
The back part actually has weight/flywheels that use momentum to move the rod.

ping http://upload.wikimedia.org/wikipedia/commons/3/3f/Pump_Jack_labelled.png

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