Scaling bar

Details Scaling bar Scaling bar

2005-06-07

2005-06-07

Smith, James G. (Department: 3723)

Compound tools

Crowbar or prybar

C254S025000

Reexamination Certificate

active

06901621

ABSTRACT:
A scaling bar for prying overhanging rocks from rocky wall structures. The scaling bar comprises an elongated tubular shaft and a first pick member attached to one end thereof, and, optionally, a second pick member attached to a second end thereof. At least one of the two pick members comprises an end portion closely fitted into engagement with the tubular shaft, a tip portion defining a substantially sharp leading edge for easier penetration in the rocky structure, and a cam element. The cam element comprises a first and a second leverage bulges, whereby by displacing the shaft, a lever is formed for dislodging unstable overhanging rocks with minimized physical effort from the workman. The second inner leverage bulge provides greater leverage to the tip portion than the first leverage bulge, but the size of the first leverage bulge is smaller, and can hence engage narrower clefts than the second leverage bulge. In use, a workman axially inserts the pick member of the scaling bar in a cleft adjacent to an unstable overhanging rock, and applies a transverse load by prying the unstable rock using the leverage provided by the first leverage bulge, hence widening the cleft. Subsequently, if necessary, the pick member is further axially driven into the cleft, and the workman again applies a transverse load to pry the rock away again using the leverage provided by the second leverage bulge. This procedure can be repeated so as to sink further into the rock bed, until the rock has been dislodged from its bed.

REFERENCES:
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patent: 138599 (1873-05-01), Wright et al.
patent: 546521 (1895-09-01), Gatti
patent: 840580 (1907-01-01), McMillan
patent: 1833451 (1931-11-01), Amera
patent: 2577924 (1951-12-01), Shacikoski
patent: 2894720 (1959-07-01), Bennett
patent: 3587121 (1971-06-01), Morrow
patent: 3619009 (1971-11-01), O'Leary
patent: 4745651 (1988-05-01), Schellenger
patent: 5409300 (1995-04-01), Bourgoin
patent: 6257553 (2001-07-01), Khachatoorian

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