Addition to Prevent Bolt Shaking Loose: Crossword Clue Answer Explained

The answer to the crossword clue "addition to prevent bolt shaking loose" is LOCKNUT — a metal fastener that stops a bolt from working itself loose under vibration. It has appeared in British quick and cryptic crosswords, including related clue forms like "fastener that resists loosening" and "metal fastener screwed on top of another (7)". Below is the full breakdown of the definition, the wordplay, and how to recognise this clue family in the grid.

The Answer: LOCKNUT

A locknut (also written "lock nut") is exactly what the clue describes: an addition to a bolt that prevents it from shaking loose. Standard nuts can gradually back off when a bolted joint is subjected to vibration, shaking, or thermal cycling. A locknut resists that loosening, either through friction, a mechanical barrier, or its geometry (nord-lock.com). Crossword clue databases record "addition to prevent bolt shaking loose" as a definition-style clue for LOCKNUT (globalclue.com).

The clue is a straight definition rather than a cryptic construction — you simply need a seven-letter noun that names a device added to a bolt to stop it rattling free. If your crossing letters give you L?C?N?T or similar, LOCKNUT should click into place.

The Cryptic Wordplay Version

The same clue family also appears in cryptic form. Clue databases list a related cryptic clue: "Security device — not luck (anag)" (globalclue.com). Here's how it parses:

• Definition: "Security device" — a locknut is a security device in the sense that it secures a bolted joint.
• Wordplay: "not luck (anag)" — take the phrase "not luck" and rearrange (anagram) its letters: N-O-T-L-U-C-K becomes L-O-C-K-N-U-T. Seven letters, a perfect fit.

This is a classic indicator-to-anagram move: "not luck" looks like ordinary English but is really just fodder for the anagram, with "(anag)" signalling the rearrangement. British setters love this kind of misdirection, where the surface reading describes the answer's purpose while the wordplay hides it in plain sight.

Other Related Clues for LOCKNUT

Clue databases collect several sibling formulations of the same idea (globalclue.com):

If you see any "bolt + loosening" or "nut + shaking" combination in a quick crossword, LOCKNUT is the first answer to try — it's the standard seven-letter fit.

What Is a Locknut? (The Real-World Object)

Understanding the actual hardware makes the clue easier to remember. A locknut is a nut designed to resist loosening under vibration or torque. The main families, described by fastener engineers, are (nord-lock.com; boyiprototyping.com):

• Friction locking: The most common approach. Nylon insert nuts (often called "Nyloc" nuts) have a nylon collar inside that grips the bolt thread, adding friction that resists loosening. Serrated and tooth lock washers work on the same friction principle.
• Mechanical locking: Uses a physical barrier to stop the nut rotating — tab washers with a bent-up tab, or locking wire threaded through the bolt head or nut and anchored nearby.
• Adhesive locking: Thread-locking liquids applied to the threads cure and bond the joint, preventing loosening. They work on any fastener size but can complicate disassembly.
• Geometry locking: Uses the shape of the fastener itself — for example, wedge-locking washer pairs with cams on one face and serrations on the other, where rotation forces movement between the cams rather than the joint.
• Double-nut (jam nut) method: A second, thinner "jam" nut is tightened against the first nut so the two bear on the threads in opposite directions, jamming together. This is why clues like "metal fastener screwed on top of another" point to LOCKNUT — you literally screw one nut on top of another.

Why does this matter for crosswords? Because setters pick definitions from real-world knowledge. "Prevent bolt shaking loose" only makes sense if you picture an engine, a bridge, or heavy machinery where vibration is the enemy — and the thing you add to fix it is a locknut.

How to Spot Fastener Clues in Crosswords

Fastener vocabulary is a recurring corner of crossword grids. Alongside LOCKNUT, keep these on your radar:

• WASHER — the flat ring placed under a nut or bolt head (sometimes the "addition" in washer-specific clues).
• BOLT itself — often clued as "fastener", "lightning" (verb sense), or "run away".
• NUT — "bolt mate", "crazy person" (slang), or "hex piece".
• SCREW — "threaded fastener", "cheat" (slang), or part of "screw up".

When a clue mentions shaking, loosening, vibration, or rattling, think hardware: LOCKNUT is the usual answer, with LOCKWASHER as the occasional longer alternative. The enumeration (the number in brackets) tells you which one fits — (7) means LOCKNUT; (10) would suggest LOCKWASHER.

Solving Tips for This Clue Family

1. Count the letters first. The enumeration is your best filter. "Addition to prevent bolt shaking loose (7)" can only be LOCKNUT in practice.
2. Check crossing letters early. If you have L?C?N?T or even just L—N-T, commit to LOCKNUT and use it to unlock the crosses.
3. Watch for anagram signals. Words like "shaking", "loose", "mixed", or "confused" can double as anagram indicators in cryptic clues — here "shaking loose" itself hints at rearranging letters, a nudge toward the "not luck (anag)" style of wordplay.
4. Remember the synonyms. If LOCKNUT doesn't fit the pattern, try "lock nut" relatives: JAMNUT (a jam nut), NYLOC (the nylon-insert brand), or LOCKWASHER.
5. Use a clue database to confirm. Sites like globalclue.com and crossword-solver.io record which clues have actually been published, so you can verify that a particular phrasing has been used before (globalclue.com).

More Crossword Clue Help on Plusword

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