Latch

A latch or catch (called sneck in Northern England and Scotland) is a type of mechanical fastener that joins two or more objects or surfaces while allowing for their regular separation.

Depending upon the type and design of the latch, this engaged bit of hardware may be known as a keeper or strike.

Latches range in complexity from flexible one-piece flat springs of metal or plastic, such as are used to keep blow molded plastic power tool cases closed, to multi-point cammed latches used to keep large doors closed.

The electronic cam lock has no mechanical keyhole, only three metal contacts are retained.

They were common from the 17th century to around 1825, and their lack of a back plate made them different from the later, and neighbouring Norfolk latch (introduced 1800–1820).

In a Norfolk latch, the handle is fitted to a backplate independently of the thumb piece.

A crossbar for a single jamb may be "captured" on the door by U-shaped bails, or anchored by a bolt on its inboard end and pivoted up and down into open cleats, making it a form of latch.

A break-action firearm is one whose barrels are hinged and a latch is operated to release the two parts of the weapon to expose the breech and allow loading and unloading of ammunition.

To fire a revolver, generally the hammer is first manually cocked and latched into place.

A switchblade uses an internal spring to produce the blade which is held in place by a button-activated latch.

A gravity knife relies on a latch to hold the folding blade in an open position once released.

Butterfly knife latches have numerous variations, including magnetic variants and some which can be opened via a spring when the handles are squeezed together.

Utility knives also often use a latch to hold a folding knife both open and closed.

To open a knife of this type may require significantly more force than the weapons variety as an added safety feature.

[13] Crossbows incorporate a type of latch to hold the drawn bowstring prior to firing.

It is named after consumer rights advocate and politician Ralph Nader, who in 1965 released the book Unsafe at Any Speed which claimed that American cars were fundamentally flawed with respect to operator safety.

Latches in seatbelts typically fasten the belt which constrains the occupant to the body of the car.

A spring latch (in this case an over-center-latch) is used to hold the walls of a springform pan in place.