Resilienty compressible support column for use in a mine

An adjustable support column for use between ceiling and floor surfaces of a mine, the column comprising:

• an outer tube having an outer end provided with a head braced against the ceiling surface and an inner end;
• an inner tube below the outer tube and having an inner end in the outer tube at the inner end thereof and an outer end provided with a foot braced against the floor surface, the tubes being coaxial to an upright axis;
• means including a wedge ring carried externally on the inner tube, tapered toward the outer tube, and engageable in the inner end of the outer tube and a support ring fixed axially externally on the inner tube and bearing axially on the wedge ring for resiliently resisting telescoping of the inner tube axially over the wedge ring into the outer tube with a predetermined force and for permitting telescoping of the wedge ring into the outer tube when the wedge ring is pressed axially into the outer tube with a force greater than the predetermined force;
• and
• interengaging screwthreads on the inner tube and the support ring for axially displacing the rings along the inner tube and fixing the rings on the inner tube at any of a multiplicity of locations therealong.