Locking devices for nuts: identification by construction detail Which locking device has a bottom cylindrical portion recessed to receive the tip of a locking set screw? Choose the correct nut type.

Identification
A ring nut (round nut) can incorporate a recessed cylindrical portion that accepts a locking set screw to secure the nut in place.

Why others are wrong

• Castle nut: uses castellations with a split pin through a drilled bolt, not a set screw recess.
• Jam nut: a thin nut used against another nut; no set screw.
• Sawn nut: has a sawn slot tightened by a small screw to clamp, not a recessed seat for a separate locking set screw.

Final Answer
Ring nut