| 摘要 |
A set point adjust mechanism is disclosed for use with process controllers to manually adjust the set point value and simultaneously change the set point value indicated. The set point adjust mechanism includes a manually actuable thumbwheel and an idler wheel mounted in contact with each other on a slider. Thumb pressure on the thumbwheel causes the slider to move so that the idler wheel contacts an indicator drive wheel. The set point value source, usually a potentiometer, is connected to the indicator drive wheel which also drives a belt that positions a pointer with respect to a scale. The pointer and scale provide the set point indication. When the pointer hits a pointer stop, or for any other reason resists motion, further rotation of the thumbwheel causes the idler wheel to move to engage a mechanical stop to prevent further thumb pressure from causing dislocation between the indicated set point value and the set point value source.
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