Rotary impulse sprinkler having an internal shaft clearing member

Claim 1

IN A ROTARY SPRINKER OF THE INPULSE TYPE WHICH INCLUDES A SPRINKLER HEAD ADAPTED TO BE ROTATABLY MOUNTED ON A VERTICAL RISER, AND INTERMITTENLY ROTATED THROUGH A SELECTED ANGLE BY AN IMPULSE HAMMER OPERATED BY WATER PASSING THROUGH THE RISER AND ISSUING FROM THE HEAD, SAID SPRINKLER HEAD HAVING MEANS DEFINING A VERTICAL PASSAGE COMMUNICATING WITH AN OBLIQUE PASSAGE, THE LATTER PASSAGE HAVING AT ITS FORWARD END A NOZZLE HAVING AN ORIFICE OPENING OF AT LEAST ABOUT 1/8", AND HAVING AT ITS REARWARD END, AND IN AXIAL ALIGNMENT THEREWITH, A VENT ORIUFICE THROUGH A WALL OF THE HEAD, A SHAFT EXTENDING SUBSTANTIALLY THE FULL LENGTH OF THE OBLIQUE PASSAGE, WITH THE FORWARD END OF THE SHAFT, WHEN THE SPRINKLER IS NOT OPERATING, PROJECTING LOOSELY INTO SAID NOZZLE ORIFICE TO BLOCK SAID ORIFICE AGAINST INGRESS BY INSECTS, A PISTON MOUNT ON THE SHAFT REARWARDLY OF SAID VERTICAL PASSAGE AND HAVING RADIAL CLEARANCE OF AT LEAST ABOUT 10/1000 OF AN INCH WITH THE WALL OF SAID OBLIQUE PASSAGE, THE REAR END OF THE SHAFT PROJECTING THROUGH SAID VENT ORIFICE AND PROVIDING A WATER DISCHARGE OPENING AROUND THE SHAFT AT LEAST AS LARGE IN AREA AS THE AREA OF THE ANNULAR CLEARANCE SPACE BETWEEN THE PISTON AND THE ADJACENT WALL OF THE OBLIQUE PASSAGE, A FORWARDLY FACING SEAT REARWARDLY OF THE PISTON FOR LIMITING REARWARD MOVEMENT OF THE SHAFT WITHIN THE OBLIQUE PASSAGE, RESILIENT MEANS URGING THE SHAFT FORWARDLY, AND A STOP SHIELD MOUNTED ON THE REAR END OF THE SHAFT EXTERIORLY OF THE HEAD FOR LIMITING FORWARD MOVEMENT OF THE SHAFT IN RESPONSE TO SAID RESILIENT MEANS, SAID SHIELD SUBSTANTIALLY CLOSING THE VENT ORIFICE TO INGRESS BY INSECTS WHILE THE SPRINKLER IS INOPERATIVE AND WHILE THE SHAFT IS IN ITS FORWARD POSITION IN RESPONSE TO SAID RESILIENT MEANS.