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Whippletree (mechanism)
A whippletree, or whiffletree, is a mechanism to distribute force evenly through linkages. It is also referred to as an equalizer, leader bar, or double tree. It consists of a bar pivoted at or near the centre, with force applied from one direction to the pivot and from the other direction to the tips. Several whippletrees may be used in series to distribute the force further, such as to simulate pressure over an area as when applying loading to test airplane wings. Whippletrees may be used either in compression or tension. They were also used for subtraction and addition calculations in mechanical computers. Tension whippletrees are used in artful hung mobiles, such as those by artist Alexander Calder. Draught whippletrees Whippletrees are used in tension to distribute forces from a point load to the traces of draught animals (the traces are the chains or straps on each side of the harness, on which the animal pulls). For these, the whippletree consists of a loose horizon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leader Bars
Leadership, both as a research area and as a practical skill, encompasses the ability of an individual, group or organization to "lead", influence or guide other individuals, teams, or entire organizations. The word "leadership" often gets viewed as a contested term. Specialist literature debates various viewpoints on the concept, sometimes contrasting Eastern and Western approaches to leadership, and also (within the West) North American versus European approaches. U.S. academic environments define leadership as "a process of social influence in which a person can enlist the aid and support of others in the accomplishment of a common and ethical task". Basically, leadership can be defined as an influential power-relationship in which the power of one party (the "leader") promotes movement/change in others (the "followers"). Some have challenged the more traditional managerial views of leadership (which portray leadership as something possessed or owned by one individual due ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roller (agricultural Tool)
The roller is an agriculture, agricultural tool used for flattening land or breaking up large clumps of soil, especially after ploughing or disc harrowing. Typically, rollers are pulled by tractors or, prior to mechanisation, a team of animals such as horses or ox, oxen. As well as for agricultural purposes, rollers are used on cricket pitches and residential lawn areas. Flatter land makes subsequent weed control and harvesting easier, and rolling can help to reduce moisture loss from cultivated soil. On lawns, rolling levels the land for mower, mowing and compacts the soil surface. Rollers may be weighted in different ways. For many uses a heavy roller is used. These may consist of one or more cylinders made of thick steel, a thinner steel cylinder filled with concrete, or a cylinder filled with water. A water-filled roller has the advantage that the water may be drained out for lighter use or for transport. In frost-prone areas a water filled roller must be drained for winte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential (mechanical Device)
A differential is a gear train with three drive shafts that has the property that the rotational speed of one shaft is the average of the speeds of the others, or a fixed multiple of that average. Functional description The following description of a differential applies to a traditional rear-wheel-drive car or truck with an open or limited slip differential combined with a reduction gearset using bevel gears (these are not strictly necessary; see spur-gear differential): Thus, for example, if the car is making a turn to the right, the main ring gear may make 10 full rotations. During that time, the left wheel will make more rotations because it has farther to travel, and the right wheel will make fewer rotations as it has less distance to travel. The sun gears (which drive the axle half-shafts) will rotate at different speeds relative to the ring gear (one faster, one slower) by, say, 2 full turns each (4 full turns relative to each other), resulting in the left wheel mak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boat Trailer
A boat trailer is designed to launch, retrieve, carry and sometimes store boats. Commercial boat trailers Commercial hydraulic boat trailers are used by marinas, boat yards, boat haulers, boat dealers and boat builders. Generally this type of trailer is not used for storage of the boat. Self-propelled Self-propelled boat movers are not strictly trailers, but hydraulically operated boat movers, with their own tractor unit. They share all of the features of hydraulic boat trailers. Non-commercial boat trailers This type of trailer is usually used by the boat owner/operator. The trailer is also used for storage. * Roll-on, also known as a "Roller style trailer", uses rubber and/or polyurethane rollers for ease of launching and loading a boat. * Glide-path, also known as a "Float-on style trailer", allows the boat to float onto the trailer; after the trailer has been partially submerged (usually of the trailer). Since its inception, it has become quite popular compared to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire-control System
A fire-control system (FCS) is a number of components working together, usually a gun data computer, a director, and radar, which is designed to assist a ranged weapon system to target, track, and hit a target. It performs the same task as a human gunner firing a weapon, but attempts to do so faster and more accurately. Naval based fire control Origins The original fire-control systems were developed for ships. The early history of naval fire control was dominated by the engagement of targets within visual range (also referred to as direct fire). In fact, most naval engagements before 1800 were conducted at ranges of . Even during the American Civil War, the famous engagement between and was often conducted at less than range. Rapid technical improvements in the late 19th century greatly increased the range at which gunfire was possible. Rifled guns of much larger size firing explosive shells of lighter relative weight (compared to all-metal balls) so greatly increa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: ''passive'' sonar means listening for the sound made by vessels; ''active'' sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ship Gun Fire-control System
Ship gun fire-control systems (GFCS) are analogue fire-control systems that were used aboard naval warships prior to modern electronic computerized systems, to control targeting of guns against surface ships, aircraft, and shore targets, with either optical or radar sighting. Most US ships that are destroyers or larger (but not destroyer escorts except Brooke class DEG's later designated FFG's or escort carriers) employed gun fire-control systems for and larger guns, up to battleships, such as . Beginning with ships built in the 1960s, warship guns were largely operated by computerized systems, i.e. systems that were controlled by electronic computers, which were integrated with the ship's missile fire-control systems and other ship sensors. As technology advanced, many of these functions were eventually handled fully by central electronic computers. The major components of a gun fire-control system are a human-controlled director, along with or later replaced by radar or te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naval Artillery
Naval artillery is artillery mounted on a warship, originally used only for naval warfare and then subsequently used for naval gunfire support, shore bombardment and anti-aircraft roles. The term generally refers to tube-launched projectile-firing weapons and excludes self-propelled projectiles such as torpedoes, rockets, and missiles and those simply dropped overboard such as depth charges and naval mines. Origins The idea of ship-borne artillery dates back to the classical era. Julius Caesar indicates the use of ship-borne catapults against Britons ashore in his ''Commentarii de Bello Gallico''. The dromons of the Byzantine Empire carried catapults and Greek fire, fire-throwers. From the late Middle Ages onwards, warships began to carry cannon, cannons of various calibres. The Mongol invasion of Java introduced cannons to be used in naval warfare (e.g. Cetbang by the Majapahit). The Battle of Arnemuiden, fought between England and France in 1338 at the start of the Hundred Y ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 2741
The IBM 2741 is a printing computer terminal that was introduced in 1965. Compared to the teletypewriter machines that were commonly used as printing terminals at the time, the 2741 offers 50% higher speed, much higher quality printing, quieter operation, interchangeable type fonts, and both upper and lower case letters. It was used primarily with the IBM System/360 series of computers, but was used with other IBM and non-IBM systems where its combination of higher speed and letter-quality output was desirable. It was influential in the development and popularity of the APL programming language. It was supplanted, starting in the mid-1970s, primarily by printing terminals using daisy wheel mechanisms. Design The IBM 2741 combines a ruggedized Selectric typewriter mechanism with IBM SLT electronics and an RS-232-C serial interface. It operates at about 14.1 characters per second with a data rate of 134.5 bits/second (one start bit, six data bits, an odd parity bit, and one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Selectric
The IBM Selectric typewriter was a highly successful line of electric typewriters introduced by IBM on 31 July 1961. Instead of the "basket" of individual typebars that swung up to strike the ribbon and page in a typical typewriter of the period, the Selectric had an "element" (frequently called a "typeball", or less formally, a "golf ball") that rotated and pivoted to the correct position before striking the paper. The element could be easily interchanged to use different fonts within the same document typed on the same typewriter, resurrecting a capability which had been pioneered by typewriters such as the Hammond Typewriter, Hammond and Blickensderfer typewriter, Blickensderfer in the late 19th century. The Selectric also replaced the traditional typewriter's horizontally-moving carriage with a roller (platen) that turned to advance the paper vertically, while the typeball and ribbon mechanism moved horizontally across the paper. The Selectric mechanism was notable for using ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog Computer
An analog computer or analogue computer is a type of computer that uses the continuous variation aspect of physical phenomena such as electrical, mechanical, or hydraulic quantities (''analog signals'') to model the problem being solved. In contrast, digital computers represent varying quantities symbolically and by discrete values of both time and amplitude (digital signals). Analog computers can have a very wide range of complexity. Slide rules and nomograms are the simplest, while naval gunfire control computers and large hybrid digital/analog computers were among the most complicated. Complex mechanisms for process control and protective relays used analog computation to perform control and protective functions. Analog computers were widely used in scientific and industrial applications even after the advent of digital computers, because at the time they were typically much faster, but they started to become obsolete as early as the 1950s and 1960s, although they remaine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mirror Support Cell
In astronomy, a mirror support cell - more commonly mirror cell - is a component of a reflecting telescope that supports the mirror in place to hold optical alignment, allow collimation adjustment, and protect it from falling out. The common usage of the word denotes the cell that holds the primary mirror (M1), however technically it could also be used to denote the support assembly (usually called a ''spider'' or ''strut'') for the secondary mirror (M2) or other mirrors. Overview Basic cells A basic mirror cell can be built using minimal calculation and simple materials. Only slightly more complex are the wooden, plastic or metal cells which are often glued and which are either not user adjustable or which have only limited adjustment and which are used in lower end commercial telescopes and smaller amateur-built telescopes. Cells for more sophisticated "small" telescopes Telescope makers seeking to build larger "small" telescopes with thinner mirrors find simple designs inade ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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