| 摘要 |
<p>A bearing system for relatively rotatable liquid conduits such as a rotating sprinkler head mounted on a fixed riser, including a two-piece casing assembly for shielding operative parts of the bearing from intrusion of external dirt and water-borne abrasive material, while permitting leakage liquid within the casing assembly to bleed outwardly, thereby preventing excessive liquid pressure in the assembly. The illustrative system includes a bearing housing having a central vertical bore and a tubular spindle rotatably mounted in the bore and projecting thereabove for attachment to a sprinkler head. The system includes spaced upper and lower seals between the fixed and rotating parts, and an external helical spring for maintaining the seals under compression, thereby minimizing entry of outside dirt and water-borne abrasive material into the annular space between the spindle and bore. A protective casing assembly forms a chamber about the spring, and includes a lower cup-shaped annular case surrounding the lower portion of the spring and having a lower internal flange underlying the spring, and an upper annular cap surrounding the upper portion of the spring and case, and provided with an upper internal flange immediately overlying the spring, and a depending cylindrical sidewall in loose telescoping relation with the case sidewall and terminating downwardly in an inturned resilient feathered edge in light peripheral contact with the case sidewall for permitting bleeding of leakage water from the chamber. The feathered edge may be provided with one or more slits to facilitate the bleeding. The feathered edge thus functions as a check valve, operable at very low actuating liquid pressure.</p> |
