A rotary sprinkler having an adjustable arc segment whose angular extent and absolute direction relative to the ground are represented by an arc indicator, which arc indicator may comprise a band whose visible length represents the angular extent and whose position on the sprinkler points to the direction. The sprinkler may have the arc segment adjusted by a movable arc limit stop that is coupled to a toggle member only at drive reversal, and the sprinkler may be converted to full circle operation by raising the arc limit stop relative to a cooperating trip tab. A buckling spring assembly used to shift the drive comprises a compression spring held between two spaced pivot members, and the drive can be built in continuous and intermittent drive versions by replacing a few normal rotary gears with multilated gears. A friction clutch having asymmetric teeth for smooth operation prevents damage to the drive during forced nozzle rotation. A nozzle assembly includes a pivotal nozzle that carries a radius adjustment screw with the head of the screw received on top a flexible portion of a top cover, which top cover has laser etched indicia relating to various adjustments of the sprinkler. A flow shut off valve includes stream straightening vanes and a collar may be used to support the sprinkler on a stake or post for above ground installation.