with parts held together by positive means, with or without relative sliding movement when the prop is subject to excessive pressure

Full Title

Props; Chocks > Telescopic props > with parts held together by positive means, with or without relative sliding movement when the prop is subject to excessive pressure

Classification Context

Section:

FIXED CONSTRUCTIONS

Class:

EARTH OR ROCK DRILLING; MINING

Subclass:

SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS

Child Classifications

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• E21D 15/18 with one part resting on a supporting medium, e.g. rubber, sand, bitumen, lead, located in the other part, with or without expulsion or displacement of the medium upon excessive pressure
• E21D 15/2 with pawl, pin, cross-piece, or the like engaging with ratchet teeth, notches, holes, or the like spaced apart at intervals
• E21D 15/22 with member, pin, cross-piece, or the like ruptured, sheared through, or permanently deformed upon excessive pressure
• E21D 15/24 with axial screw-and-nut, rack-and-worm, or like mechanism