A strut is a structural component designed to resist longitudinal compression. Struts provide outwards-facing support in their lengthwise direction, which can be used to keep two other components separate, performing the opposite function of a tie. They are commonly used in architecture and engineering, for instance as components of an automobile chassis, where they can be passive braces to reinforce the chassis and/or body, or active components of the suspension. In piping, struts restrain movement of a component in one direction while allowing movement or contraction in another direction.
An automotive suspension strut combines the primary function of a shock absorber (as a damper), with the ability to support sideways loads not along its axis of compression, somewhat similar to a sliding pillar suspension, thus eliminating the need for an upper suspension arm. This means that a strut must have a more rugged design, with mounting points near its middle for attachment of such loads.
The most common form of strut in an automobile is the MacPherson strut. MacPherson struts are often purchased by the automakers in sets of four completed sub-assemblies: These can be mounted on the car bodies as part of the manufacturers' own assembly operations. The MacPherson strut combines a shock absorber and a spring in a single unit, by means of which each wheel is attached to the car body.
Lift struts were commonly used in early aircraft to support wings, stabilizers, control frames in gliders and hang gliders, and in landing gear. Since the 1930s they were mostly replaced with cantilever constructions, and became rare except in light aircraft. These structural members are frequently loaded in tension, but may vary between tension and compression as the aircraft maneuvers.
Struts are still widely used to attach the landing gear, particularly in retractable-gear aircraft, and provide damping during the takeoff and landing roll; here they are often called oleo struts.
Famous quotes containing the word strut:
“It is dangerous for a woman to defy the gods;
To taunt them with the tongue’s thin tip,
Or strut in the weakness of mere humanity,
Or draw a line daring them to cross;”
—Anne Spencer (1882–1975)
“As boys without bonds to their fathers grow older and more desperate about their masculinity, they are in danger of forming gangs in which they strut their masculinity for one another, often overdo it, and sometimes turn to displays of fierce, macho bravado and even violence.”
—Frank Pittman (20th century)
“The state of society is one in which the members have suffered amputation from the trunk, and strut about so many walking monsters,—a good finger, a neck, a stomach, an elbow, but never a man.”
—Ralph Waldo Emerson (1803–1882)