| 摘要 |
A reaction drive sprinkler, particularly of the large gun type, is provided with an improved drive assembly adapted for full- or part-circle rotation of the sprinkler in steps about the axis of a water supply standpipe. The sprinkler includes a relatively large and outwardly inclined range tube from which a relatively high energy water stream is projected a substantial distance for irrigation purposes. The drive assembly comprises a drive nozzle mounted on the range tube for bleed passage of a relatively low energy portion of the irrigation water supplied to the range tube and for directing this low energy stream into engagement with one of a pair of oppositely angled deflector spoons at the end of a counterbalanced and pivotally mounted reaction drive arm. The drive nozzle is movable with respect to the range tube and is mechanically shifted by a reversing mechanism for aligning the low energy stream first for cyclic interruption by one of the deflector spoons to rotate the sprinkler stepwise in one direction through a preselected arcuate path and then for cyclic interruption by the other deflector spoon to rotate the sprinkler stepwise in an opposite rotational direction back through the preselected path. In one preferred form, the range tube is supported for rotation by a bearing assembly which includes a force-biased seal member responsive to increasing water pressure for increasing frictional resistance to rotation whereby the stepwise movement of the sprinkler is maintained substantially uniform throughout a range of water pressures. Moreover, the range tube is advantageously provided with a discharge nozzle assembly which is adjustable to select the angle of inclination of the projected high energy water stream. |
