Motorized support legs operation

[Supermario]

This is gonna sound stupid but , I've never seen motorized support legs operated from a remote before. Can someone please explain how the legs are operated ? Is it when your servo unlatches the 5th wheel, the legs run down and then vice versa when hooking up? I just got the tamiya kit and in the instructions it makes reference to joystick functions make legs go up and down.? How is that possible? With no connection to trailer?

Any help would be appreciated thanks.

Mario