Well logging apparatus
An elongated body member having a plurality of crank arms pivotally attached thereto, such crank arms disposed generally symmetrically around the perimeter of the body member. At a first end of each crank arm is a contact pad for maintaining substantial contact with the sidewalls of a borehole. The second end of each crank arm is pivotally coupled to a drive link which is in turn attached to a piston which is longitudinally slidably mounted within the body member. Longitudinal movement of the piston within the body member will result in a corresponding generally lateral movement, either extension or retraction, of the crank arms and thereby of the contact pads attached thereto. A mechanism is provided for allowing the piston to traverse a limited range of longitudinal movement within the body member, a force being exerted upon the piston such that the piston is urged to the bound of such travel which will yield the maximum lateral extension of the contact pads. This mechanism is also capable of retracting the contact pads within the general confines of the body member. A mechanism is also provided for determining the longitudinal position of the piston within the body member and for thereby obtaining a functional indication of the diameter of the borehole.
- Assignee:
- Dresser Industries, Inc.
- Patent Number(s):
- US 4432143
- OSTI ID:
- 6629563
- Country of Publication:
- United States
- Language:
- English
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