Hydraulic power unit for landing legs

In what?

Ny, same concept.
Closed loop system.
From tank reservoir thru a reversing valve to one side of the ram. Out from the other side back to a reversing valve to pump to reservoir.
Then the reversing valves on engaged and the fluid goes the opposite direction.
Now if all you do is preform a search on Youtube for Hydraulic systems, you can see a video.

above post may be true for most slides. It if the legs have springs they my only be single sided cylinders and the pump pumps the oil thru the valve to the cylinder and the valve closes. When you want them to go up, the valve opens and the spring pushes the oil back to the tank without the pump.

Thanks for the help, the reason I asked the question I am changing my electric landing legs to hydraulic on a 2009 Sierra. The pump I have to complete the project is not the same stock # as was quoted by Lippert. I just was trying to find out if there is a difference between the pump for the slides and the legs. The pump would be a double action.
Any info would be appreciated.
Wayne