A pintle is a pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge. Other applications include pintle and lunette ring for towing, and pintle pins securing casters in furniture.
Pintle/gudgeon sets have many applications, for example: in sailing to hold the rudder onto the boat; in transportation a pincer-type device clamps through a lunette ring on the tongue of a trailer; in controllable solid rocket motors a plug moves into and out of the motor throat to control thrust.
In electrical cubicle manufacture, a pintle hinge is a hinge with fixed and moving parts. The hinge has a pin "pintle" and and can be both external and internal. The most common type consists of 3 parts. One part on the body of the cubicle, one part on the door and the third part is the pintle.
In transportation, a pintle hitch is a type of tow hitch that uses a tow ring configuration to secure to a hook or a ball combination for the purpose of towing an unpowered vehicle.
As a weapon mount a pintle-mount is used with machine guns as the mounting hardware that mates the machine gun to a vehicle or tripod. Essentially the pintle is a bracket with a cylindrical bottom and a cradle for the gun on top; the cylindrical bottom fits into a hole in the tripod while the cradle holds the gun.
In furniture, a pintle is usually fitted to a caster; the pintle is then inserted into a base, fixing the caster to that base.
In rocketry, a pintle injector uses a single-feed fuel injector rather than the hundreds of smaller holes used in a typical rocket engine. This simplifies the engine, reducing cost and improving reliability, while surrendering some performance. Grumman used the pintle-based Rocketdyne RS-18 for the Ascent stage of the Apollo Lunar Module. TRW used this same injector for the Descent Propulsion System on Apollo's Lunar Module. Notable modern uses are in the Merlin engines developed by SpaceX.