Borehole centralizer with positively indexable contact arms

Claim 1

An apparatus for centering a well logging instrument in an earth borehole, comprising: an elongated shaft adapted for movement through an earth borehole, said shaft having at least one longitudinal recess therein; a pair of contact arm carriers slidably and rotatably mounted on said shaft, said carriers having a serrated surface; a pair of coil springs, each having a first end connected to one of said contact arm carriers; a pair of adjustable retainers slidably and rotatably mounted on said shaft and attached to the second end of said coil springs; means for adjusting the force exerted by said coil springs; a plurality of contact arms, said arms being pivotally connected between said pair of contact arm carriers; at least one disengagable indexing member having serrations matable with the serrations on at least one of said contact arm carriers, said indexing member also having a projection adapted to mate with said longitudinal recess in said shaft and; means for securing said locking member, said contact arm carrier and said shaft in relative position to one another.

Claim 2

An apparatus for centering a well logging instrument in an earth borehole, comprising: an elongated shaft adapted for movement through an earth borehole, said shaft having at least one longitudinal recess therein; a pair of contact arm carriers slidably and rotatably mounted on said shaft, said carriers having a serrated surface; a pair of coil springs, each having a first end connected to one of said contact arm carriers; a pair of adjustable retainers slidably and rotatably mounted on said shaft and attached to the second end of said coil springs; means for adjusting the force exerted by said coil springs; a plurality of contact arms, said arms being pivotally connected between said pair of contact arm carriers; at least one disengagable indexing member having serrations matable with the serrations on at least one of said contact arm carriers, said indexing member also having a projection adapted to mate with said longitudinal recess in said shaft and; means for securing said locking member, said contact arm carrier and said shaft in relative position to one another.

Claim 3

An apparatus for centralizing an instrument within a borehole, comprising: an elongated shaft member, having a longitudinal slot therein, adapted for movement through a borehole; at least one concentric carrier member rotationally and longitudinally movable with respect to said shaft member, said carrier member having a radially serrated inner surface; arms means connected to said at least one carrier member for contacting the sidewall of said borehole; and means for selectively indexing and positively locking said arm means in a selected one of a plurality of fixed rotational positions relative to said shaft member, said means including an insertable indexing member having a radially serrated surface complimentary to that of said carrier member and an extension portion longitudinally slidable within at least a portion of said longitudinal slot in said shaft member.

Claim 4

An apparatus for centralizing an instrument within a borehole, comprising: an elongated shaft member, having a longitudinal slot therein, adapted for movement through a borehole; at least one concentric carrier member rotationally and longitudinally movable with respect to said shaft member, said carrier member having a radially serrated inner surface; arms means connected to said at least one carrier member for contacting the sidewall of said borehole; and means for selectively indexing and positively locking said arm means in a selected one of a plurality of fixed rotational positions relative to said shaft member, said means including an insertable indexing member having a radially serrated surface complimentary to that of said carrier member and an extension portion longitudinally slidable within at least a portion of said longitudinal slot in said shaft member.

Claim 7

An apparatus for centralizing an instrument within a borehole, comprising: an elongated shaft member having first and second longitudinal recesses located proximate the first and second end thereof, respectively; first and second slidably and rotatably mounted carrier members concentrically located on said shaft each of said carrier members having a radially serrated surface; a plurality of arm members bridgingly mounted between said first and second carrier members; indexing means for allowing said carrier members to be selectively fixed in one of a plurality of positions relative to said shaft said indexing means including; a first indexing member having a radially serrated surface complimentary to that of said first carrier member and an extension portion slidable within said first longitudinal recess; and a second indexing member having a radially serrated surface complimentary to that of said second carrier member and an extension portion slidable within said second recess.

Claim 8

An apparatus for centralizing an instrument within a borehole, comprising: an elongated shaft member having first and second longitudinal recesses located proximate the first and second end thereof, respectively; first and second slidably and rotatably mounted carrier members concentrically located on said shaft each of said carrier members having a radially serrated surface; a plurality of arm members bridgingly mounted between said first and second carrier members; indexing means for allowing said carrier members to be selectively fixed in one of a plurality of positions relative to said shaft said indexing means including; a first indexing member having a radially serrated surface complimentary to that of said first carrier member and an extension portion slidable within said first longitudinal recess; and a second indexing member having a radially serrated surface complimentary to that of said second carrier member and an extension portion slidable within said second recess.