| US Patent: 446,592 
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| Pipe Wrench | 
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| Patentees: |  
 | Thomas Jefferson Duncan (exact or similar names) - Leadville, CO |  | Dennis McManus (exact or similar names) - Leadville, CO |  
 
 
 
 
| Manufacturer: |  | Not known to have been produced |  
 
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| Patent Dates: |  
| Applied: | Jul. 01, 1890 |  
| Granted: | Feb. 17, 1891 |  
 
USPTO (New site tip)| Patent Pictures: |  |  |  | Thomas Jefferson Duncan and Dennis McManus patent February 17,  1891 |  Google Patents
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                        Stan Schulz
 
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| Description: |  | A rocking link that connects the fixed and movable jaws has an internal spur that engages rack teeth cut in one face of the slot in the movable jaw. |  |