| 摘要 |
A fully adjustable concentric dial indicator comprises a first annular scale member which is adapted to carry indicia around the periphery thereof defining a first circular scale. The second scale member is disposed coaxially of the first and is adapted to carry indicia around the periphery thereof defining a second circular scale. Friction clutch means couple the scale members to a support for selective rotation of the scale members relative to the support in either direction about the common axis. The friction clutch means includes a manually engageable ring member to which only the first of the scale members is fixed and which is rotatable about the common axis of the scale members against the effect of the friction clutch means associated with the first scale member. First and second concentric rotatable shafts are aligned with the axis and respectively carry first and second pointers. The pointers cooperate, in response to rotation of the shafts, with scales definable on the respective ones of the scale members. A projection extends inwardly toward the axis from the ring member. A finger is coupled to the second scale member and extends outwardly therefrom into the path along which the projection moves in response to rotation of the ring member about the indicator axis.
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