![antonov an-2 ha-mkf at kemble arp](https://upload.wikimedia.org/wikipedia/commons/f/f5/Antonov_an-2_ha-mkf_at_kemble_arp.jpg)
A strut is a structural component commonly found in
engineering
Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad rang ...
,
aeronautics
Aeronautics is the science or art involved with the study, design, and manufacturing of air flight–capable machines, and the techniques of operating aircraft and rockets within the atmosphere. The British Royal Aeronautical Society identifies ...
,
architecture
Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and constructing building ...
and
anatomy
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
. Struts generally work by resisting longitudinal
compression
Compression may refer to:
Physical science
*Compression (physics), size reduction due to forces
*Compression member, a structural element such as a column
*Compressibility, susceptibility to compression
* Gas compression
*Compression ratio, of a ...
, but they may also serve in tension.
Human anatomy
Part of the functionality of the
clavicle
The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the rig ...
is to serve as a strut between the
scapula
The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eithe ...
and
sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...
, resisting forces that would otherwise bring the
upper limb
The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulde ...
close to the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
. Keeping the upper limb away from the thorax is vital for its
range of motion
Range of motion (or ROM), is the linear or angular distance that a moving object may normally travel while properly attached to another. It is also called range of travel (or ROT), particularly when talking about mechanical devices and in mechanic ...
. Complete lack of clavicles may be seen in
cleidocranial dysostosis, and the abnormal proximity of the shoulders to the
median plane
The median plane also called a mid-sagittal plane is used to describe the sagittal plane as it bisects the body vertically through the midline marked by the navel, dividing the body exactly in left and right side.
The term parasagittal plane is u ...
exemplifies the clavicle's importance as a strut.
Architecture and construction
Strut is a common name in
timber framing
Timber framing (german: Holzfachwerk) and "post-and-beam" construction are traditional methods of building with heavy timbers, creating structures using squared-off and carefully fitted and joined timbers with joints secured by large wooden ...
for a support or brace of
scantling
Scantling is a measurement of prescribed size, dimensions, or cross sectional areas.
Shipping
In shipbuilding, the scantling refers to the collective dimensions of the framing (apart from the keel) to which planks or plates are attached to form th ...
s lighter than a post. Frequently struts are found in roof framing from either a tie beam or a king post to a principal rafter. Struts may be vertically plumb or leaning (then called canted, raking, or angled) and may be straight or curved. In the U.K., strut is generally used in a sense of a lighter duty piece: a king post carries a ridge beam but a king strut does not, a queen post carries a plate but a queen strut does not, a crown post carries a crown plate but a crown strut does not.
Strutting or
blocking between
floor joists adds strength to the floor system.
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''.
In piping, struts restrain movement of a component in one direction while allowing movement or contraction in another direction.
Strut channel
Strut channel, often referred to colloquially by one of several manufacturer trade names, is a standardized formed structural system used in the construction and electrical industries for light structural support, often for supporting wiring, plumb ...
made from
steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
,
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
, or
fibre-reinforced plastic
Fibre-reinforced plastic (FRP; also called fibre-reinforced polymer, or in American English ''fiber'') is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass (in fibreglass), carbon (in carbon-fib ...
is used heavily in the building industry and is often used in the support of
cable tray
In the electrical wiring of buildings, a cable tray system is used to support insulated electrical cables used for power distribution, control, and communication. Cable trays are used as an alternative to open wiring or electrical conduit syste ...
s and other forms of
cable management
Cable management refers to management of electrical or optical cable in a cabinet or an installation. The term is used for products, workmanship or planning.
Cables can easily become tangled, making them difficult to work with, sometimes res ...
, and pipes support systems.
Aircraft
Bracing struts and wires of many kinds were extensively used in early
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
to stiffen and strengthen, and sometimes even to form, the main functional airframe. Throughout the 1920s and 1930s they fell out of use in favour of the low-drag
cantilever
A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a canti ...
construction. Most aircraft bracing struts are principally loaded in compression, with wires taking the tension loads. Lift struts came into increasing use during the changeover period and remain in use on smaller aircraft today where ultimate performance is not an issue. Typically they are applied to a high-wing
monoplane
A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes.
A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...
and act in tension during flight.
Struts have also been widely used for purely structural reasons to attach engines,
landing gear
Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...
and other loads. The oil-sprung legs of retractable landing gear are still called ''
Oleo strut
An oleo strut is a pneumatic air–oil hydraulic shock absorber used on the landing gear of most large aircraft and many smaller ones. This design cushions the impacts of landing and damps out vertical oscillations.
It is undesirable for an airp ...
s''.
Automobiles
As components of an automobile
chassis
A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of an artificial object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart ...
, struts can be passive braces to reinforce the chassis and/or body, or active components of the suspension. An example of an active unit would be a
coilover
A coilover is an automobile suspension device. The name coilover is an abbreviation of "coil-over shock absorber".
Description
Coilovers are found on many vehicles, from RC cars to normal passenger cars, race cars and 4x4 vehicles. They are som ...
design in an
automotive suspension. The
coilover
A coilover is an automobile suspension device. The name coilover is an abbreviation of "coil-over shock absorber".
Description
Coilovers are found on many vehicles, from RC cars to normal passenger cars, race cars and 4x4 vehicles. They are som ...
combines a shock absorber and a spring in a single unit.
A common form of
automotive suspension strut in an automobile is the
MacPherson strut
The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles, and is named for American automotive engineer Ear ...
. 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. A MacPherson strut combines the primary function of a
shock absorber
A shock absorber or damper is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy (typically heat) which is then dissipated. Most sh ...
(as a
damper
A damper is a device that deadens, restrains, or depresses. It may refer to:
Music
* Damper pedal, a device that mutes musical tones, particularly in stringed instruments
* A mute for various brass instruments
Structure
* Damper (flow), a mechan ...
), with the ability to support sideways loads not along its axis of compression, somewhat similar to a
sliding pillar
A sliding pillar suspension is a form of independent front suspension for light cars. The stub axle and wheel assembly are attached to a vertical pillar or kingpin which slides up and down through a bush or bushes which are attached to the veh ...
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.
Another common type of strut used in
air suspension
Air suspension is a type of vehicle suspension powered by an electric or engine-driven air pump or compressor. This compressor pumps the air into a flexible bellows, usually made from textile-reinforced rubber. Unlike hydropneumatic suspension, ...
is an air strut which combines the shock absorber with an air spring and can be designed in the same fashion as a
coilover
A coilover is an automobile suspension device. The name coilover is an abbreviation of "coil-over shock absorber".
Description
Coilovers are found on many vehicles, from RC cars to normal passenger cars, race cars and 4x4 vehicles. They are som ...
device. These come available in most types of suspension setups including
beam axle
A beam axle, rigid axle or solid axle is a dependent suspension design in which a set of wheels is connected laterally by a single beam or shaft. Beam axles were once commonly used at the rear wheels of a vehicle, but historically they have als ...
and
MacPherson strut
The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles, and is named for American automotive engineer Ear ...
style design.
Transportation-related struts are used in "load bearing" applications ranging from both highway and off-road suspensions to automobile hood and hatch window supports to aircraft wing supports. The majority of struts feature a bearing, but only for the cases, when the strut mounts operate as steering pivots. For such struts, the bearing is the wear item, as it is subject to constant impact of vibration and its condition reflects both wheel alignment and steering response. In vehicle suspension systems, struts are most commonly an assembly of coil-over spring and shock absorber. Other variants to using a coil-over spring as the compressible load bearer include support via pressurized nitrogen gas acting as the spring, and rigid (hard tail) support which provides neither longitudinal compression/extension nor damping.
History
Struts were created in the 1970s in which automakers transitioned from large rear-wheeled drive vehicles to more fuel-efficient front-wheeled drive vehicles. The entire suspension system was changed in accordance to meet the new style of vehicles. The new styles of vehicles left less room for the traditional system; which was called the short-arm/ long-arm suspension systems. This caused the
MacPherson strut
The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles, and is named for American automotive engineer Ear ...
system to become the new standard for all automobiles including front-wheeled and rear-wheeled vehicles. The
MacPherson strut
The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles, and is named for American automotive engineer Ear ...
system does not require an upper control arm, bushings, or a pivot shaft like previous models.
Options on vehicles
Struts are not necessarily needed components on vehicles which separate the springs and shock absorbers, while the shocks support no weight. There are also some vehicles with the option of only having one pair of struts on one set of wheels while the other pair uses a separate selection of shocks and springs. This singular pair of struts are almost always a
MacPherson strut
The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles, and is named for American automotive engineer Ear ...
. These choices are made for various reasons including the balance of initial cost, performance, and other elements. Some vehicles use a "double wishbone," suspension system which exclusively uses shock absorbers. Sports cars seem to favor this suspension style; however, the Porsche 911 favors traditional struts.
Maintenance
Struts keeps your suspension aligned, along with numerous other functions. To check if a set of struts is failing; simply walk to each side of the wheel and begin to bounce the car up and down. As the car is pushed down, let it bounce back into position. If it continues to bounce up and down, consider taking your vehicle to a mechanic for replacement. You can also check your strut car to see if it's leaking oil. Bad struts could possibly lead to many issues including the breaking of a wheel, flattening of a tire, damaged power steering, broken springs, broken joints, and many more issues in your suspension system. Keep all of these in mind as you drive your vehicle with bad struts.
Gallery
File:Strut.jpg, ORI strut, off-road application of strut
File:Strut bar2.JPG, Strut bar
File:Wing Brace strut.JPG, Compression strut on Piper Pawnee
The PA-25 Pawnee is an agricultural aircraft produced by Piper Aircraft between 1959 and 1981. It remains a widely used aircraft in agricultural spraying and is also used as a tow plane, or tug, for launching gliders or for towing banners. In ...
(low-wing aircraft)
File:Shorts360airsey.jpg, Tension strut on Shorts 360
The Short 360 (also SD3-60; also Shorts 360)Mondey, David. ''Encyclopedia of the World's Commercial and Private Aircraft''. New York: Crescent Books, 1981. , p. 228. is a commuter aircraft that was built by UK manufacturer Short Brothers during ...
(high-wing aircraft)
File:MacPhersonStrut.jpg, MacPherson strut suspension
File:Su-30MKI nosewheel.jpeg, Nosewheel oleo strut on Su-30MKI aircraft
See also
*
Cabane strut
In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...
*
Chapman strut
The Chapman strut is a design of independent rear suspension used for light cars, particularly sports and racing cars. It takes its name from, and is best known for its use by, Colin Chapman of Lotus.
The characteristic feature of the Chapman ...
*
Jury strut
In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in c ...
*
Lift strut
In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...
*
Spacers and standoffs
In general, a spacer is a solid material used to separate two parts in an assembly. Spacers can vary in size from microns to centimeters. They can be made of metal, plastic, glass, and other materials. Shapes include flat sheet, cylindrical and ...
*
Strut bar
A strut bar, strut brace, or strut tower brace (STB) is an automotive suspension accessory on a monocoque or unibody chassis to provide extra stiffness between the strut towers.
With a MacPherson strut suspension system where the spring and sho ...
References
{{Authority control
Automotive suspension technologies
Timber framing
ja:ストラット式サスペンション