A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. The clutch acts as a mechanical linkage between the engine and transmission; and briefly disconnects, or separates the engine from the Transmission system, and therefore the drive wheels, whenever the pedal is depressed, allowing the driver to smoothly change gears.
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for this is the law of the lever. Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal mechanism does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account departures from the ideal.
A machine is a human-made device that uses power to apply forces and control movement to perform an action. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors that monitor performance and plan movement, often called mechanical systems.
A drawing board is, in its antique form, a kind of multipurpose desk which can be used for any kind of drawing, writing or impromptu sketching on a large sheet of paper or for reading a large format book or other oversized document or for drafting precise technical illustrations. The drawing table used to be a frequent companion to a pedestal desk in a study or private library, during the pre-industrial and early industrial era.
A desktop computer is a personal computer designed for regular use at a single location on or near a desk due to its size and power requirements. The most common configuration has a case that houses the power supply, motherboard, disk storage ; a keyboard and mouse for input; and a computer monitor, speakers, and, often, a printer for output. The case may be oriented horizontally or vertically and placed either underneath, beside, or on top of a desk.
A desk or bureau is a piece of furniture with a flat table-style work surface used in a school, office, home or the like for academic, professional or domestic activities such as reading, writing, or using equipment such as a computer. Desks often have one or more drawers, compartments, or pigeonholes to store items such as office supplies and papers. Desks are usually made of wood or metal, although materials such as glass are sometimes seen.
A rolltop desk is a 19th-century reworking of the pedestal desk with, in addition, a series of stacked compartments, shelves, drawers and nooks in front of the user, much like the bureau à gradin or the Carlton House desk. In contrast to these, the compartments and the desktop surface of a rolltop desk can be covered by means of a tambour consisting of linked wooden slats that roll or slide through slots in the raised sides of the desk. In that, it is a descendant in function, and partly in form, of the cylinder desk of the 18th century. It is a relative of the tambour desk, whose slats retract horizontally rather than vertically. The rolltop desk was re-invented by Jacob Alles in Jasper, Indiana in 1879. "About 1760 Jean-François Oeben designed a new type of bureau: the original rolltop desk. The writing area can be covered by a shutter made of flexible slats, which is rolled round a cylinder hidden behind the top tier of drawers. In the Château de Versailles is found the most famous example of this type of desk, the "bureau du roi," which was begun by Oeben in 1760 and finished by Riesener. Riesener made several rolltop desks; the one for Thierrry de Ville d'Avray indicates that the Louis XV style was not yet regarded as outmoded in the 1780s".
A secretary desk or escritoire is made of a base of wide drawers topped by a desk with a hinged desktop surface, which is in turn topped by a bookcase usually closed with a pair of doors, often made of glass. The whole is usually a single, tall and heavy piece of furniture.
A mechanical calculator, or calculating machine, is a mechanical device used to perform the basic operations of arithmetic automatically. Most mechanical calculators were comparable in size to small desktop computers and have been rendered obsolete by the advent of the electronic calculator.
An escapement is a mechanical linkage in mechanical watches and clocks that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands. The impulse action transfers energy to the clock's timekeeping element to replace the energy lost to friction during its cycle and keep the timekeeper oscillating. The escapement is driven by force from a coiled spring or a suspended weight, transmitted through the timepiece's gear train. Each swing of the pendulum or balance wheel releases a tooth of the escapement's escape wheel, allowing the clock's gear train to advance or "escape" by a fixed amount. This regular periodic advancement moves the clock's hands forward at a steady rate. At the same time, the tooth gives the timekeeping element a push, before another tooth catches on the escapement's pallet, returning the escapement to its "locked" state. The sudden stopping of the escapement's tooth is what generates the characteristic "ticking" sound heard in operating mechanical clocks and watches. The first mechanical escapement, the verge escapement, was invented in medieval Europe during the 13th century, and was the crucial innovation which led to the development of the mechanical clock. The design of the escapement has a large effect on a timepiece's accuracy, and improvements in escapement design drove improvements in time measurement during the era of mechanical timekeeping from the 13th through the 19th century.
A pocket watch is a watch that is made to be carried in a pocket, as opposed to a wristwatch, which is strapped to the wrist.
In horology, a movement, also known as a caliber, is the mechanism of a watch or timepiece, as opposed to the case, which encloses and protects the movement, and the face, which displays the time. The term originated with mechanical timepieces, whose clockwork movements are made of many moving parts. The movement of a digital watch is more commonly known as a module.
A striking clock is a clock that sounds the hours audibly on a bell or gong. In 12-hour striking, used most commonly in striking clocks today, the clock strikes once at 1:00 A.M., twice at 2:00 A.M., continuing in this way up to twelve times at 12:00 P.M., then starts again, striking once at 1:00 P.M., twice at 2:00 P.M., up to twelve times at 12:00 A.M.
A preselector gearbox is a type of manual transmission mostly used on passenger cars and racing cars in the 1930s, in buses from 1940-1960 and in armoured vehicles from the 1930s to the 1970s. The defining characteristic of a preselector gearbox is that the gear shift lever allowed the driver to "pre-select" the next gear, usually with the transmission remaining in the current gear until the driver pressed the "gear change pedal" at the desired time.
A balance spring, or hairspring, is a spring attached to the balance wheel in mechanical timepieces. It causes the balance wheel to oscillate with a resonant frequency when the timepiece is running, which controls the speed at which the wheels of the timepiece turn, thus the rate of movement of the hands. A regulator lever is often fitted, which can be used to alter the free length of the spring and thereby adjust the rate of the timepiece.
A mechanical watch is a watch that uses a clockwork mechanism to measure the passage of time, as opposed to quartz watches which function electronically via a small battery, or radio watches, which are quartz watches synchronized to an atomic clock via radio waves. A mechanical watch is driven by a mainspring which must be wound either periodically by hand or via a self-winding mechanism. Its force is transmitted through a series of gears to power the balance wheel, a weighted wheel which oscillates back and forth at a constant rate. A device called an escapement releases the watch's wheels to move forward a small amount with each swing of the balance wheel, moving the watch's hands forward at a constant rate. The escapement is what makes the 'ticking' sound which is heard in an operating mechanical watch. Mechanical watches evolved in Europe in the 17th century from spring powered clocks, which appeared in the 15th century.
A fan is a powered machine used to create a flow of air. A fan consists of a rotating arrangement of vanes or blades, which act on the air. The rotating assembly of blades and hub is known as an impeller, rotor, or runner. Usually, it is contained within some form of housing, or case. This may direct the airflow, or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors, handcranks, and internal combustion engines.
A marine steam engine is a steam engine that is used to power a ship or boat. This article deals mainly with marine steam engines of the reciprocating type, which were in use from the inception of the steamboat in the early 19th century to their last years of large-scale manufacture during World War II. Reciprocating steam engines were progressively replaced in marine applications during the 20th century by steam turbines and marine diesel engines.
An equation clock is a mechanical clock which includes a mechanism that simulates the equation of time, so that the user can read or calculate solar time, as would be shown by a sundial. The first accurate clocks, controlled by pendulums, were patented by Christiaan Huyghens in 1657. For the next few decades, people were still accustomed to using sundials, and wanted to be able to use clocks to find solar time. Equation clocks were invented to fill this need.
A mounted or bar corkscrew is a device screwed or clamped to a wall or counter top, used to draw corks from beer, wine or other bottles.
