Mine roof warning indicator

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Description

FIG. 1 is a prospective view of the mine roof warning indicator showing our new design.

FIG. 2 is a perspective view with the indicator means in the danger warning position of the mine roof warning indicator showing our new design.

FIG. 3 is a top view of the mine roof warning indicator showing our new design.

FIG. 4 is a bottom view of a mine roof warning indicator showing our new design.

Referenced Cited
U.S. Patent Documents
2725843 December 1955 Koski
3111655 November 1963 Kotarsky et al.
3137268 June 1964 Hornwood
3786503 January 1974 Webb et al.
Patent History
Patent number: D258499
Type: Grant
Filed: Dec 21, 1978
Date of Patent: Mar 10, 1981
Inventors: Larry L. Brown (St. Louis, MO), Robert G. Hamm (St. Louis, MO)
Primary Examiner: W. Stallard
Attorney: Neal Kalishman
Application Number: 5/971,949
Classifications
Current U.S. Class: D10/104
International Classification: D1006;