What is the minimum breakaway torque for used all-metallic and nonmetallic self-locking nuts sized 3/4-16, fine threaded?

What is the minimum breakaway torque for used all-metallic and nonmetallic self-locking nuts sized 3/4-16, fine threaded?

• A. 25 in-lbs
• B. 75 in-lbs
• C. 100 in-lbs
• D. 50 in-lbs

Answer: (D)

Breakaway torque is the initial turning force needed to overcome the locking mechanism inside a self-locking nut and start loosening or tightening the fastener. For used all-metallic and nonmetallic self-locking nuts sized 3/4-16 with fine threads, the minimum acceptable breakaway torque is 50 inch-pounds. This value ensures the locking feature remains effective under vibration even after prior use, while not being so high that ordinary maintenance would require excessive torque to loosen the nut. A value like 25 in-lbs would be too low to reliably resist vibration and prevent loosening, while 75 or 100 in-lbs would exceed the typical tolerance for this size and thread type, potentially causing unnecessary stress or making disassembly harder than needed. So 50 in-lbs best matches the standard requirement for these nuts.

Breakaway torque is the initial turning force needed to overcome the locking mechanism inside a self-locking nut and start loosening or tightening the fastener. For used all-metallic and nonmetallic self-locking nuts sized 3/4-16 with fine threads, the minimum acceptable breakaway torque is 50 inch-pounds. This value ensures the locking feature remains effective under vibration even after prior use, while not being so high that ordinary maintenance would require excessive torque to loosen the nut.

A value like 25 in-lbs would be too low to reliably resist vibration and prevent loosening, while 75 or 100 in-lbs would exceed the typical tolerance for this size and thread type, potentially causing unnecessary stress or making disassembly harder than needed. So 50 in-lbs best matches the standard requirement for these nuts.