Releasably retaining telescoping tubing segments

In a telescoping tube assembly of adjustable length comprising at least two elongated tubular members, a first one of which has a bore formed therein to telescopically receive the second therewithin, a locking means assembly for releasably restraining said elongated tubular members against relative axial telescoping movement disposed within a receiving bore of the second of said elongated tubular members, said locking means assembly comprising, in combination, an expander head member of truncated conical configuration and a radially expandable frictional brake member in operative engagement with said expander head member;

• said locking means assembly being characterized in that:
• (a) said truncated conical expander head member comprises a body with a cylindrical body segment and a conical tip segment, and wherein said expander head member is positioned fast within the receiving bore of the second of said elongated tubular members, said conical segment having a threaded bore concentric with the axis of said expander head member;
• (b) said radially expandable frictional brake member comprising a body with a cap portion with a plurality of radially expandable friction shoes of arcuately segmented configuration depending therefrom, said friction shoes being joined to said cap portion by hinge means and with each said friction shoe having an inner wall surface converging toward said cap portion and configured to mate with and be substantially complementary to the outer surface of the truncated conical tip segment of said expander head member;
• (c) bolt means comprising a threaded shank engaged with the threaded bore of said expander head and adapted for rotation relative to said expander head member for axial movement of said friction shoes in engagement with said conical tip segment of said expander head member;
• (d) each of said hinge means joining said friction shoes to said cap member including two axially spaced apart bridge zones and with at least one of said bridge zones being normally disposed radially outwardly of the conical portion of said expander head member, and with another of said bridge zones being disposed axially outwardly from the tip of said conical portion, the arrangement being such that said first and second bridge zones flex in oppositely disposed arcuate directions, one to another, so as to force the outer surfaces of said friction shoes against the inner surface of the bore of the second of said elongated tubular members.