Abstract: An elongate irrigation pipe is rotatably supported on a wheeled support member. A first gear is secured against rotation on the support member with the pipe extending rotatably therethrough. A rotator arm is secured to and extends radially outwardly from the pipe and has an orbital, fluid actuated motor mounted thereon. A second gear on the drive shaft of the orbital motor engages the teeth on the first gear, whereby actuation of the motor causes the rotator arm to rotate about the first gear and thus rotate the pipe. An operative connection between the pipe and wheel supports produces movement of the pipe over a field. Fluid pressure supply lines extend along the pipe to supply the orbital motor. Branch lines extend inwardly into the pipe, progress longitudinally through the pipe past the first gear and support member, and then exit from the pipe on the opposite side to continue along the length of the pipe to a second motor spaced longitudinally along the pipe line therefrom.