Torque wrench
Llave dinamométrica
- Date
- 1918 · confidence medium
- Place
- New York, New York, United States
- Credited to
- Conrad Bahr; Paul Sturtevant
- Field
- Tools
⚠️ Disputed: the sources disagree.
What it is
A wrench with an indicator or release mechanism that measures the torque applied to a bolt or nut so it is neither over- nor under-tightened. Conrad Bahr developed it in 1918 at the New York water department and Paul Sturtevant patented it in 1938.
The attribution to Bahr (1918) and Sturtevant's patent (1938, which gave rise to the modern form) are recorded in secondary sources; the priority between the two is debated.
What it led to
- controlled tightening in engines, aircraft and bridges
- aircraft maintenance with specified torque
- click-type and digital torque wrenches