Definition
The straight, unthreaded portion of a bolt, screw, rivet, or drill bit located between the head and the threaded or working end. On a bolt, the shank is the smooth cylindrical body that passes through the parts being joined and carries the shear load. On a drill bit, it is the plain end that is gripped by the chuck.
Plain English
The smooth middle section of a bolt or drill bit — the part with no threads or cutting edges. On a bolt, it sits between the head and the threads. On a drill, it is the end that fits into the drill itself.
Context Anchor
Seen when identifying aircraft bolts, choosing the correct bolt length, or inspecting fasteners during maintenance.
Derivation
From Old English 'sceanca' meaning 'leg' or 'shin' — the straight part between two ends. The same idea applies here: the straight 'leg' of the bolt or bit between its head and its working end.
Why Pilots Care
On structural bolts, the smooth shank — not the threads — is what carries shear loads across joined parts. Using a bolt with the wrong grip length means the threads end up in the shear plane, which the bolt is not designed to handle. Knowing what the shank is and what it does is part of selecting and inspecting hardware correctly.
Intuition Check
Shank does not mean the whole bolt. In this context, it means the smooth body section between the head and the threaded end.
Example Sentence 1
The technician checked that the bolt's shank, not its threads, was bearing against the joined parts.
Example Sentence 2
A longer shank on the screwdriver allowed access to the deeply recessed fastener.