trunnion

The trunnions are the protrusions from the side of the barrel that rest on the carriage.

A trunnion is a cylindrical protrusion used as a mounting and/or pivoting point.

Usages

In weapons

• In a cannon, the trunnions are the two projections on the side of the barrel which mount the barrel in the carriage. As they allowed the muzzle to be raised and lowered easily, and made it easier to fix it to a movable carriage, the integral casting of trunnions is seen by military historians as one of the most important advances in early field artillery.^[1]
• On firearms, the barrel is sometimes mounted in a trunnion, which in turn is mounted to the receiver. This usage is common for tubular or pressed metal frame guns, such as the Kalashnikov, PPSh, Uzi, Sten, and others.

In vehicles

• In older cars, especially those by the Triumph Motor Company, the trunnion is part of the suspension and either allows free movement of the rear wheel hub in relation to the chassis or allows the front wheel hub to rotate with the steering. On many cars the trunnion is machined from a brass or bronze casting and is prone to failure.
• In aviation, the term refers to the structural component that attaches the landing gear to the airframe. For aircraft equipped with retractable landing gear, the trunnion is pivoted to permit rotation of the entire gear assembly.
• In heavy equipment, such as a bulldozer, the term refers to the protrusions on the vehicle frame on which the blade frame attaches and hinges allowing vertical movement.
• In Chevrolet GMC C/K pickup trucks, the term refers to the tailgate attachment points. Rather than using conventional tailgate hinges, trunnions are used to permit quick toolless removal and installation of the pickup tailgate.
• In Trailers,Murray Trailer The term refers to the type of suspension used on a two axle configuration with eight tires, i.e. four tires per axle. This type of trailer suspension is commonly used in the western United States and is allowed 60,000 pounds (27,000 kg) to be loaded on that axle group.

In other technology

• In steam engines, they are supporting gudgeon pins on either side of an oscillating steam cylinder. They are usually tubular and convey steam.
• On communication satellites, the antennas are usually mounted on a pair of trunnions to allow the beam pattern to be correctly pointed on the Earth from the geostationary orbit.
• On stage lighting instruments, a trunnion is a bracket attached to both ends of a striplight that allows the striplight to be mounted on the floor. Sometimes trunnions are also equipped with casters to allow the striplight to be moved easily.
• In woodworking, they are the assembly that holds a saw's arbor to the underside of the saw table.
• In Waste Collection the trunnion is the bar on the front of a Dumpster that connects to the back of a garbage truck.
• On the Space Shuttle, trunnion pins are affixed to the sides of payload items allowing them to be secured to receivers mounted on the sills of the payload bay. These receivers can be remotely commanded to secure and release selected items. Similar keel pins protrude from the nadir side of payload items, into matching holes in the bottom of the payload bay.

Trunnion bearings

In avionics, these are self-contained concentric bearings that are designed to offer fluid movement in a critical area of the steering.

The term is also used to describe the wheel that a rotating cylinder runs on. For example, a lapidary (stone-polishing) cylinder runs on a pair of rollers, similar to trunnions. The sugar industry uses rotating cylinders up to 22 feet in diameter and 131 feet long weighing around 1000 tons. These rotate at around 30 revolutions per hour. They are supported on a pathring which runs on trunnions. Similar devices called rotary kilns are used in cement manufacturing.

References

• http://www.cape-international.com/suspension_and_steering.tpl
• Floor trunnion