US Patent: 250,464 - Differential screw


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US Patent: 250,464

Differential screw

Patentee:

John Thomson (exact or similar names) - Brooklyn, NY

USPTO Classifications:

100/289, 269/241

Tool Categories:

work holding : vises : bench vises

Assignees:

None

Manufacturer:

Not known to have been produced

Witnesses:

Lyman H. Essex

Herman T. C. Kraus

Patent Dates:
Applied:	May 28, 1881
Granted:	Dec. 06, 1881

Patent Pictures:

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Description:

This invention uses a simple clutch mechanism to allow a screw to act in the ordinary way when resistance is light, but convert to a differential screw when resistance increases.