A gudgeon is a circular fitting, often made of metal, which is affixed to a surface. It allows for the pivoting of another fixture. It is generally used with a pintle

Pintle

A pintle is a pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge.A pintle/gudgeon set is used in many spheres, 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...

, which is a pin which pivots in the hole in the gudgeon. As such, a gudgeon is a simple bearing

Bearing (mechanical)

A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...

.

Winged gudgeons

A winged gudgeon is one that has extensions that increase its ability to adhere to the fixed surface. At the beginning of the industrial revolution

Industrial Revolution

The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

, winged gudgeons were used to support water wheel

Water wheel

A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...

 shafts, and later, steam engine shafts.

Gudgeon pin

In engines, a gudgeon pin (UK, wrist pin US) joins the small end of a connecting rod

Connecting rod

In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....

 to a piston

Piston

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from...

 or crosshead.

Buildings

In buildings pintles and gudgeons are used for working shutters. Shutters were used to protect the glazing as well as help keep heat in the building at night during the colder months. Today shutters are experiencing a comeback as protection from wind born debris from storms. Architects have made use of both reclaimed historical shutter hardware as well as used stainless sailing hardware for various projects. Other uses are closet doors, barn doors, storm doors, etc. All uses require hold backs of some sort to keep shutter or door from "flapping in the wind".

Sailing

In sailing

Sailing

Sailing is the propulsion of a vehicle and the control of its movement with large foils called sails. By changing the rigging, rudder, and sometimes the keel or centre board, a sailor manages the force of the wind on the sails in order to move the boat relative to its surrounding medium and...

, pintles insert into gudgeons that are normally affixed to the transom

Transom (nautical)

In naval architecture, a transom is the surface that forms the stern of a vessel. Transoms may be flat or curved and they may be vertical, raked forward, also known as a retroussé or reverse transom, angling forward from the waterline to the deck, or raked aft, often simply called "raked", angling...

 of a boat. Normally, the corresponding pintle fitting on the rudder slides, lowers or clips into the gudgeon. There are variations where gudgeons are mounted to the rudder and boat, and a pivot clevis pin is inserted into these gudgeons, or the pintles are fastened to the boat, and gudgeons are attached to the rudder. In any case, the fitting with the hole is referred to as a gudgeon. They are used to attach the rudder

Rudder

A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...

 to the boat so that it can swing freely. The rudder can then be turned with the tiller

Tiller

A tiller or till is a lever attached to a rudder post or rudder stock of a boat that provides leverage for the helmsman to turn the rudder...

. There must be at least two gudgeon/pintle sets for stability in the rudder's attachment to the transom. The pintles must face the same direction for insertion into the gudgeons and usually one is a bit longer so it can be the first into its gudgeon, giving some stability for the insertion of the other pintle. To prevent the rudder from rising out of the gudgeons there is often some preventer such as rudder weight or a locking device slid across the path of the pintle's removal from the upper gudgeon.

On some boats there are split pins through the pintail to stop gudgeons lifting. In addition while the bottom fitting is a gudgeon turning on a pintail the upper two fittings are a pair of gudgeons each with a pin joining them with split pin/washer to stop them coming out.