| 摘要 |
A chuck actuator has a cylinder extending along a main axis and a piston axially displaceable in the cylinder, forming therein two compartments, and having an axially backwardly extending stem also centered on the axis and formed with two respective intake passages each having one end opening into the respective compartment and another end opening at a respective location on the stem. A connector rotatable about the axis on the stem is provided with respective fittings communicating with the locations. First and second axially spaced bearings prevent the connector from moving axially on the stem. Fluid is fed under pressure alternately to the fittings to pressurize and depressurize the respective compartments and thereby axially displace the piston in the cylinder. Normally the cylinder is connected to a chuck body and the piston to a chuck-actuating member for fluid actuation of the member. An axially extending guide fixed on the connector slidably receives an axially extending bar slidable and a third bearing distinct from the first and second bearings links the bar to the cylinder for joint axial movement therewith but rotation relative thereto. A sensor including at least one element carried on the bar and another element on the connector adjacent the guide and engageable with the one element in a predetermined axial position thereof relative to the connector detects when the elements are in the predetermined position. |
