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US 5,967,702 AGranted
Quick-release pit prop
OwnerHarmen Reinaldus Vogelzanginventor
Life of this patent
Estimating the term…
Abstract
A pit prop has two opposed ends and comprises two bearing plates located at the ends, two telescopically displaceable prop elements, a number of separate resiliently compressible rubber discs arranged adjacent each other and a tubular indicating element. The prop includes a further bearing plate with the discs being located between two bearing plates to permit yielding of the pit prop under a load. The indicating element has markings thereon to indicate the load condition of the prop. The prop includes a locking device for releasably locking the prop elements with respect to each other.
Claims17
A pit prop having two opposed ends, comprising
- two bearing members for bearing against opposed walls to be held in a spaced relationship, with a first bearing member being located at one end of the pit prop and a second bearing member being located at the other end of the pit prop;
- two elongate prop elements that are located with respect to each other to be telescopically displaceable, the prop elements having locking means for releasably locking the prop elements with respect to each other in selected positions, one of the prop elements having the first bearing member connected thereto at a free end thereof and the other prop element having a bearing plate connected thereto at an end thereof remote from said one prop element;
- yielding means disposed between the second bearing member and the bearing plate, to act between the second bearing member and the bearing plate, the yielding means including a number of separate resiliently compressible disc elements arranged adjacent each other, the yielding means for pre-loading means for pre-loading the pit prop when the pit prop is positioned between opposed walls to be held in a spaced relationship;
- and
- load indicating means in the form of an indicating element which is connected to the second bearing member, the indicating element defining markings thereon which indicate relative positions of the indicating element, representing a load, with respect to the yielding means when the yielding means is compressed under a load, in use.
2 more elements
A pit prop having two opposed ends, comprising
- two bearing members for bearing against opposed walls to be held in a spaced relationship, with a first bearing member being located at one end of the pit prop and a second bearing member being located at the other end of the pit prop;
- two elongate prop elements in the form of an inner tubular element and an outer tubular element within which the inner tubular element is located to be telescopically displaceable therein, one of the tubular elements having the first bearing member connected thereto at a free end thereof and the other tubular element having a bearing plate connected thereto at an end thereof remote from said one tubular element;
- yielding means disposed between the second bearing member and the bearing plate, to act between the second bearing member and the bearing plate, the yielding means including at least one resiliently compressible member and pre-loading means for pre-loading the pit prop when the pit prop is positioned between opposed walls to be held in a spaced relationship;
- and
- locking means for releasably locking the inner tubular element with respect to the outer tubular element, the locking means including nut means comprising two nut body portions which are rotatably connectable to the outer tubular element and which have an internal screw-thread formed thereon, the inner tubular element having an external screw-thread formed thereon which is complementary to the screw-head of the nut body portions, the nut body portions being pivotally connected to each other to be displaceable with respect to each other between a first position in which the internal screw-thread of the nut body portions operatively engages the external screw-thread of the inner tubular element to permit displacement of the inner tubular element with respect to the outer tubular element via engagement of the screw-threads, and a second position in which the body portions are disengaged from the inner tubular element to permit the outer and inner tubular elements to be freely displaced with respect to each other to allow for adjustment of the length of the pit prop.
2 more elements
Dependencies are inferred from the claim text.