Abstract: Wheel line irrigation apparatus provided with a plurality of rotary, impact-type, high volume sprinklers, mounted on trunk lines each of which are self leveling. The pipeline is axially affixed to laterally spaced wheels; the pipeline including a main line, having a substantially horizontal longitudinal axis, and a plurality of dropped line portions defining cradle-like structures. A series of trunk lines, in fluid communication with the pipeline and rotatably connected to the pipeline by support bearings, are nestled within the cradles. Each of the trunk lines is provided with a sprinkler, rotatable about a vertical axis. The sprinklers are maintained in the upright position, even when the pipeline is on uneven ground, as the trunk lines pivot within the cradles because of the low center of gravity. The inlet port of each nozzle is located at or below the longitudinal axis of the main line to hold oscillations to a minimum.