Human power

clockwork radiopedal radiowind-up radio
In the most common arrangement, an internal electric generator is run by a mainspring, which is wound by a hand crank on the case. Turning the crank winds the spring and a full winding will allow several hours of operation. Alternatively, the generator can charge an internal battery. Radios powered by handcranked generators are not new, but their market was previously seen as limited to emergency or military organizations. The modern clockwork radio was designed and patented in 1991 by British inventor Trevor Baylis as a response to the HIV/AIDS crisis. He envisioned it as a radio for use by poor people in developing countries without access to batteries.


A remontoire should not be confused with a maintaining power spring, which is used only to keep the timepiece going while it is being wound. Remontoires are used because the timekeeping mechanism in clocks and watches, the pendulum or balance wheel, is never isochronous; its rate is affected by changes in the drive force applied to it. In spring-driven timepieces, the drive force declines as the mainspring runs down. In weight-driven clocks the drive force, provided by a weight suspended by a cord, is more constant, but imperfections in the gear train and variations in lubrication also cause small variations.


horse-drawn carriagecarriageshorse carriage
Carriages normally have suspension using leaf springs, elliptical springs (in the 19th century) or leather strapping. Working vehicles such as the (four-wheeled) wagon and (two-wheeled) cart share important parts of the history of the carriage, as does too the fast (two-wheeled) chariot. The word carriage (abbreviated carr or cge) is from Old Northern French cariage, to carry in a vehicle.


Swords and longer blades, in modern times, are often crafted of 5160 carbon spring steel, which is not as hard or brittle as a high carbon steel (such as 1095), but is more durable and less prone to breakage, and therefore more suitable for longer weapons. 5160 carbon spring steel is sometimes used for leaf springs in American trucks, making it readily available in the US. In Europe, EN-45 is more commonly used. Many bladesmiths are able to forge a special type of steel using a technique called pattern welding, producing a metal erroneously referred to as Damascus steel.

Ride quality

rideRide controlsmooth ride
Similarly, a lower center of gravity is more ideal for handling, but low ground clearance limits suspension travel, requiring stiffer springs. Ambulances have a special need for a high level of ride quality, in order to avoid further injury to the already ill passengers. Early vehicles, like the Ford Model T, with its leaf spring, live axle suspension design, were both uncomfortable and handled poorly. Historically, weight was key to allowing cars such as the Rolls-Royce Silver Cloud and the Cadillac in the 1950s and 1960s to have a more comfortable ride quality.

Unsprung mass

unsprung weightsprung massun-sprung weight
If the vehicle does not have adequate wheel location in the vertical plane (such as a rear-wheel drive car with Hotchkiss drive, a live axle supported by simple leaf springs), vertical forces exerted by acceleration or hard braking combined with high unsprung mass can lead to severe wheel hop, compromising traction and steering control. A beneficial effect of unsprung mass is that high frequency road irregularities, such as the gravel in an asphalt or concrete road surface, are isolated from the body more completely because the tires and springs act as separate filter stages, with the unsprung mass tending to uncouple them.

Pierre Le Roy

PierreLe Roy
His technique for temperature compensation was highly efficient in that it worked without changing the length of the spiral balance spring, which he had discovered to be isochronous only at a precise given length (i.e. when frequency is independent of amplitude, so that a mechanical clock or watch runs at the same rate regardless of changes in its drive force, so it keeps correct time as the mainspring unwinds). After having designed plans in 1754, he constructed his first chronometers by 1756, and accomplished his masterpiece in 1766.


However spring driven-timepieces were much less accurate than weight-driven clocks, because the drive force (torque) exerted by a coiled spring, unlike a weight, is not constant, but is maximum when the spring is wound up and declines as the spring unwinds to turn the movement's wheels. The main cause of inaccuracy in early spring-driven timepieces was the large variation in force provided by the mainspring as it unwound during the timepiece's running period. The force of the mainspring, transmitted through the clock's gears, gives pushes to the oscillating balance wheel which keeps time.

Timmis system

Timmis was an innovative design of double coiled springs, originally used for railway rolling stock, such as on the Barsi Light Railway c1889, as formulated by Everard Calthrop (1857–1927). The inventor was Illius Augustus Timmis US Patent 432341 was filled in 1889 and published in 1890. Bogie as used with railway rolling stock. Coil spring. Leaf spring - an older an simpler system of springs.


[[File:Circle radians.gif|thumb|right|300px|An arc of a circle with the same length as the radius of that circle subtends an angle of 1 radian. The circumference subtends an angle of 2[[pi|

Bending moment

A bending moment is the reaction induced in a structural element when an external force or moment is applied to the element causing the element to bend. The most common or simplest structural element subjected to bending moments is the beam. The diagram shows a beam which is simply supported at both ends. Simply supported means that each end of the beam can rotate; therefore each end support has no bending moment. The ends can only react to the shear loads. Other beams can have both ends fixed; therefore each end support has both bending moment and shear reaction loads. Beams can also have one end fixed and one end simply supported.

Music box

musical boxmusic boxesmusic-box
The cylinders were normally made of metal and powered by a spring. In some of the costlier models, the cylinders could be removed to change melodies, thanks to an invention by Paillard in 1862, which was perfected by Metert of Geneva in 1879. In some exceptional models, there were four springs, to provide continuous play for up to three hours. The very first boxes at the end of the 18th century made use of metal disks. The switchover to cylinders seems to have been completed after the Napoleonic wars. In the last decades of the 19th century, however, mass-produced models such as the Polyphon and others all made use of interchangeable metal disks instead of cylinders.


toystoylineToy industry
In 1943 Richard James was experimenting with springs as part of his military research when he saw one come loose and fall to the floor. He was intrigued by the way it flopped around on the floor. He spent two years fine-tuning the design to find the best gauge of steel and coil; the result was the Slinky, which went on to sell in stores throughout the United States. After the Second World War as society became ever more affluent and new technology and materials (plastics) for toy manufacture became available, toys became cheap and ubiquitous in households across the Western World.


For broader coverage of this topic, please see Motor vehicle. For other uses, please see Car (disambiguation) or Automobile (disambiguation).


vehiclesvehicularroad vehicle
Mechanical strain is another method of storing energy, whereby an elastic band or metal spring is deformed and releases energy as it is allowed to return to its ground state. Systems employing elastic materials suffer from hysteresis, and metal springs are too dense to be useful in many cases. Flywheels store energy in a spinning mass. Because a light and fast rotor is energetically favorable, flywheels can pose a significant safety hazard. Moreover, flywheels leak energy fairly quickly and affect a vehicle's steering through the gyroscopic effect. They have been used experimentally in gyrobuses. Wind energy is used by sailboats and land yachts as the primary source of energy.

Young's modulus

Young’s modulusmodulustensile modulus
Hooke's law for a stretched wire can be derived from this formula: :where it comes in saturation : and But note that the elasticity of coiled springs comes from shear modulus, not Young's modulus. The elastic potential energy stored in a linear elastic material is given by the integral of the Hooke's law: now by explicating the intensive variables: This means that the elastic potential energy density (i.e., per unit volume) is given by: : or, in simple notation, for a linear elastic material:, since the strain is defined.


Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency. The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency. For example: if a newborn baby's heart beats at a frequency of 120 times a minute, its period, T, — the time interval between beats—is half a second (60 seconds divided by 120 beats).


D'Arsonval galvanometertangent galvanometernull detector
Today the main type of galvanometer mechanism, still in use, is the moving coil, D'Arsonval/Weston type. Modern galvanometers, of the D'Arsonval/Weston type, are constructed with a small pivoting coil of wire, called a spindle, in the field of a permanent magnet. The coil is attached to a thin pointer that traverses a calibrated scale. A tiny torsion spring pulls the coil and pointer to the zero position. When a direct current (DC) flows through the coil, the coil generates a magnetic field. This field acts against the permanent magnet. The coil twists, pushing against the spring, and moves the pointer. The hand points at a scale indicating the electric current.

Rubber band

elastic bandRubberbandrubber bands
A rubber band (also known as an elastic band, gum band or lacky band) is a loop of rubber, usually ring shaped, and commonly used to hold multiple objects together. The rubber band was patented in England on March 17, 1845 by Stephen Perry. Most rubber bands are manufactured out of natural rubber or, especially at larger sizes, elastomer, and are sold in a variety of sizes.


resonantresonant frequencyresonance frequency
Systems with one degree of freedom, such as a mass on a spring, pendulums, balance wheels, and LC tuned circuits have one resonant frequency. Systems with two degrees of freedom, such as coupled pendulums and resonant transformers can have two resonant frequencies. As the number of coupled harmonic oscillators grows, the time it takes to transfer energy from one to the next becomes significant. The vibrations in them begin to travel through the coupled harmonic oscillators in waves, from one oscillator to the next.

Moment of inertia

rotational inertiamoments of inertiamoment of inertia tensor
The moment of inertia, otherwise known as the angular mass or rotational inertia, of a rigid body is a quantity that determines the torque needed for a desired angular acceleration about a rotational axis; similar to how mass determines the force needed for a desired acceleration. It depends on the body's mass distribution and the axis chosen, with larger moments requiring more torque to change the body's rotation rate. It is an extensive (additive) property: for a point mass the moment of inertia is just the mass times the square of the perpendicular distance to the rotation axis.


spiralsspherical spiralwhorl
when water is draining in a sink is often described as a spiral, or as a conical helix. 2) quite explicitly, definition 2 also includes a cylindrical coil spring and a strand of DNA, both of which are quite helical, so that "helix" is a more useful description than "spiral" for each of them; in general, "spiral" is seldom applied if successive "loops" of a curve have the same diameter.


clothes pegclothes-pinclothes pins
He added what he called a "coiled fulcrum" made from a single wire, this was the spring that held the wooden pieces together, acted as a spring forcing them to shut, and as a fulcrum on which the two halves could rock, eliminating the need for a separate component, and reducing manufacturing costs. This became the first successful spring-actuated clothespin, being manufactured and sold in huge quantities all across the United States. The state of Vermont, and its capitol of Montpelier, in particular, quickly became what The New York Times has called "The Silicon Valley of Clothespin Manufacturing", the United States Clothespin Company opening in 1887 to manufacture Moore's improved design.


Such is the case, for instance, of a long pendulum that is free to move in two dimensions; of a mass attached to a fixed point by a perfectly elastic spring; or of any object that moves under influence of an attractive force that is directly proportional to its distance from a fixed attractor. Unlike Keplerian orbits, however, these "harmonic orbits" have the center of attraction at the geometric center of the ellipse, and have fairly simple equations of motion. In electronics, the relative phase of two sinusoidal signals can be compared by feeding them to the vertical and horizontal inputs of an oscilloscope.

Tempering (metallurgy)

Light blue – 337 C – springs, wood-cutting saws. Grey-blue – 371 C and higher – structural steel. Annealing (metallurgy). Austempering. Precipitation strengthening. Tempered glass. A thorough discussion of tempering processes. Webpage showing heating glow and tempering colors.