| 摘要 |
<p>A system for indicating a position of a piston (221) inside a cylinder of a control valve. The indicator of the present invention has an enclosed shaft (310) which prevents the use of the shaft to tamper with the piston. The position of the shaft inside a shaft housing (301) is indicated using a pair of magnets, a first magnet (311) is connected to a first end of the shaft and a second magnet (320) is slidably mounted to an outside of the shaft housing. As the shaft moves the first magnet inside the housing, the second magnet moves outside the housing. The second magnet and shaft housing are enclosed in a transparent housing to prevent damage. The shaft housing (321) has a threaded connector (302) for connecting the shaft housing to a valve housing over the piston to prevent leakage through the shaft housing. A groove (314) in a second end of the shaft receives teeth from a toothed retaining ring (352) affix the shaft to the piston. The second end of the shaft also has a tapered end (313) to allow the shaft to be connected to the piston without removing the piston from the housing.</p> |
