cotter pin

noun

Machinery.

1. a cotter having a split end that is spread after being pushed through a hole to prevent it from working loose.

cotter pin

noun

1. a split pin secured, after passing through holes in the parts to be attached, by spreading the ends

2. a tapered pin threaded at the smaller end and secured by a nut after insertion

Word History and Origins

Origin of cotter pin¹

First recorded in 1890–95

Example Sentences

The inspector general said the airline’s maintenance provider failed to insert a cotter pin on a critical flight control component that put some 30,000 passengers at risk.

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Attorney Timothy Loranger says a missing safety cotter pin caused a malfunction in the helicopter’s tail rotor.

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On every bolt use a castellated nut and a cotter pin, or an ordinary nut and a lock washer, so the bolt will not work loose.

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By lightly tapping in the taper cotter pin little by little, sufficient pressure is put on the cutter to make it an easy matter to completely re-face an old seat or form a new one.

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Each bar is composed of three pieces, two side pieces from 15 ins. below to 6 ins. above springing lines and a connecting roof bar attached to the side bars by cotter pins.

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