| 摘要 |
An adjustable riser is provided for coupling an irrigation sprinkler to a water supply line, wherein the riser is adapted for quick and easy longitudinal adjustment to variably select the elevational position of the sprinkler relative to ground level. The adjustable riser comprises a pair of telescopically interfitting inner and outer riser tubes coupled respectively to the sprinkler and to the water supply line. The inner riser tube has a keyway formed on the exterior surface thereof, and the outer riser tube carries at least one key protruding into and engaged with the keyway. In the preferred form, the keyway comprises at least one recessed channel defined by an axially spaced succession of part-circumferential segments interconnected at opposite ends by axial segments extending in opposite directions. This channeled keyway permits longitudinal adjustment in riser length by displacement of the outer riser tube relative to the inner riser tube in a sequence of back and forth part-rotational steps with intervening axial steps, with the key tracking along the keyway to prevent full circle rotation of the outer riser tube relative to the inner riser tube.
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