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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
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Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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Moments that changed communities, movements, institutions and the nation.
Katherine Johnson’s mathematical calculations helped guide some of America’s most important early space missions while she confronted the racial and gender barriers faced by Black women in twentieth-century America.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
 | This article includes a list of general references but lacks sufficient corresponding inline citations. (December 2007) |
A coil spring is a mechanical device that typically is used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. It is made of an elastic material formed into the shape of a helix that returns to its natural length when unloaded.
Under tension or compression, the material (wire) of a coil spring undergoes torsion. The spring characteristics therefore depend on the shear modulus.
A coil spring may also be used as a torsion spring: in this case the spring as a whole is subjected to torsion about its helical axis. The material of the spring is thereby subjected to a bending moment, either reducing or increasing the helical radius. In this mode, it is the Young's modulus of the material that determines the spring characteristics.
Spring rate is the measurement of how much load (in pounds) a coil spring can hold until it compresses 1 inch (2.54 cm). The spring rate is normally specified by the manufacture. If a spring has a rate of 100 then the spring would compress 1 inch with 100 pounds (45 kg) of load.[1]
Types of coil spring are:
Coil springs have many applications; notable ones include:
Coil springs are commonly used in vehicle suspension. These springs are compression springs and can differ greatly in strength and in size depending on application. A coil spring suspension can be stiff to soft depending on the vehicle it is used on. Coil spring can be either mounted with a shock absorber or mounted separately. Coil springs in trucks allow them to ride smoothly when unloaded and once loaded the spring compresses and becomes stiff. This allows the vehicle to bounce less when loaded. Coil spring suspension is also used in high performance cars so that the car can absorb bumps and have low body roll. In off-road vehicles they are used because of their range of travel they allow at the wheel.
Coil springs used in the engine are compression springs and play an important role in closing the valves that feed air and let exhaust gasses out of the combustion chamber. The spring is attached to a rocker that is connected to the valve.
Tension and extension coil springs of a given material, wire diameter and coil diameter exert the same force when fully loaded; increased number of coils merely (linearly) increases free length and compressed/extended length.
Metal coil springs are made by winding a wire around a shaped former – a cylinder is used to form cylindrical coil springs.
Coil springs for vehicles are typically made of hardened steel. A machine called an auto-coiler takes spring wire that has been heated so it can easily be shaped. It is then fed onto a lathe that has a metal rod with the desired coil spring size. The machine takes the wire and guides it onto the spinning rod as well as pushing it across the rod to form multiple coils. The spring is then ejected from the machine and an operator will put it in oil to cool off. The spring is then tempered to lose the brittleness from being cooled. The coil size and strength can be controlled by the lathe rod size and material used. Different alloys are used to get certain characteristics out of the spring, such as stiffness, dampening and strength [2]
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
A spring is a device consisting of an elastic but largely rigid material (typically metal) bent or molded into a form (especially a coil) that can return into shape after being compressed, extended or twisted. Springs can store energy when compressed, when extended, and/or when twisted. In everyday use, the term most often refers to coil springs, but there are many different spring designs. Modern springs are typically manufactured from spring steel. An example of a non-metallic spring is the bow, made traditionally of flexible yew wood, which when drawn stores energy to propel an arrow. When a conventional spring, without stiffness variability features, is compressed or stretched from its resting position, it exerts an opposing force approximately proportional to its change in length (this approximation breaks down for larger deflections). The rate or spring constant of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve. An extension or compression spring's rate is expressed in units of force divided by distance, for example or N/m or lbf/in. A torsion spring is a spring that works by twisting; when it is twisted about its axis by an angle, it produces a torque proportional to the angle. A torsion spring's rate is in units of torque divided by angle, such as N·m/rad or ft·lbf/degree. The inverse of spring rate is compliance, that is: if a spring has a rate of 10 N/mm, it has a compliance of 0.1 mm/N. The stiffness (or rate) of springs in parallel is additive, as is the compliance of springs in series. Springs are made from a variety of elastic materials, the most common being spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after manufacture. Some non-ferrous metals are also used, including phosphor bronze and titanium for parts requiring corrosion resistance, and low-resistance beryllium copper for springs carrying electric current.
A spring-loaded camming device (also SLCD, cam or friend) is a piece of rock climbing or mountaineering protection equipment. It consists of two, three, or four cams mounted on a common axle or two adjacent axles, so that pulling on the axle forces the cams to spread further apart. It is then attached to a sling and carabiner at the end of the stem. The SLCD is used by pulling on the "trigger" (a small handle) so that the cams retract together, then inserting it into a crack or pocket in the rock and releasing the trigger to allow the cams to expand. A pull on the rope, such as that generated by a climber falling, will cause a properly placed SLCD to convert the pulling force along the stem of the unit into outwards pressure on the rock, producing massive amounts of friction and preventing the removal of the unit from the rock. Due to the large forces exerted on the rock when an SLCD is fallen on, it is very important that SLCDs are only placed in solid, strong rock.
A coil spring is a mechanical device that typically is used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. It is made of an elastic material formed into the shape of a helix that returns to its natural length when unloaded. Under tension or compression, the material (wire) of a coil spring undergoes torsion. The spring characteristics therefore depend on the shear modulus. A coil spring may also be used as a torsion spring: in this case the spring as a whole is subjected to torsion about its helical axis. The material of the spring is thereby subjected to a bending moment, either reducing or increasing the helical radius. In this mode, it is the Young's modulus of the material that determines the spring characteristics.
A spring-gun, also known as a booby trap gun, is a gun, often a shotgun, rigged to fire when a string or other triggering device is tripped by contact of sufficient force to "spring" the trigger so that anyone stumbling over or treading on it would discharge the gun. Setting or maintaining a spring-gun is illegal in many places.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Brown v. Board of Education in 1954.
