| 摘要 |
A rotatable valve stem in a fluid (e.g. water) hydrant controls the axial position of a plug relative to a valve seat to control fluid-flow through the valve seat. The valve stem is threaded into a bushing of the hydrant so that rotational movement of the stem causes axial movement thereof. According to the invention, rotation of such valve stem is motorized by the coupling of a rotatably-driven drive shaft of an electric motor to the valve stem. The motor and, optionally, a gearing arrangement are enclosed by a protective housing supported by the hydrant. The motor is slidably mounted within the protective housing to accommodate axial movement of the motor caused by the axial movement of the valve stem and its coupled motor drive shaft. According to a preferred embodiment, such sliding movement is effected by the combination of one or more pins operatively coupled to the motor and extending radially outward relative to the motor drive shaft axis, and a like number of axially-extending slots formed in the protective housing and adapted to receive and guide such pins.
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