 The locking pliers is an example of a four-bar, one degree of freedom mechanical linkage; or a five-bar, two DOF linkage when the adjustment screw is considered. Mechanical linkages are a series of rigid links connected with joints to form a closed chain, or a series of closed chains. Each link has two or more joints, and the joints have various degrees of freedom to allow motion between the links. A linkage is called a mechanism if two or more links are movable with respect to a fixed link. Mechanical linkages are usually designed to take an input and produce a different output, altering the motion, velocity, acceleration, and applying mechanical advantage. Image File history File linksMetadata Download high resolution version (948x696, 63 KB) locking pliers source:me File links The following pages link to this file: Linkage (mechanical) Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ...
Image File history File linksMetadata Download high resolution version (948x696, 63 KB) locking pliers source:me File links The following pages link to this file: Linkage (mechanical) Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. ...
The phrase degrees of freedom is used in three different branches of science: in physics and physical chemistry, in mechanical and aerospace engineering, and in statistics. ...
In mechanical engineering, aeronautical engineering and robotics, degrees of freedom (DOF) describes flexibility of motion. ...
Wind turbines A machine is any mechanical or organic device that transmits or modifies energy to perform or assist in the performance of tasks. ...
In physics and engineering, mechanical advantage (MA) is the factor by which a machine multiplies the force put into it. ...
A linkage designed for no motion is called a structure or truss. See this article for more information. Truss bridge for a single track railway, converted to pedestrian use and pipeline support. ...
History
 A flyball governor for flow control. A water turbine spins the governor, which controls the water flow, which feeds the turbine, creating a speed-regulated machine. Mechanical linkages are a fundamental part of machine design, and yet many simple linkages were not well understood nor invented until the 19th century. Consider a stick: it has six degrees of freedom, three of which are the coordinates of its centre in space, the other three describing its rotation. Once nudged between a boulder and fulcrum it is constrained to a particular motion, to act as a lever to move the boulder. When more links are added and joined in various ways their collective motion can be further defined. Very complicated and precise motions can be designed into a linkage with only a few parts. Image File history File links Centrifugal_governor. ...
Image File history File links Centrifugal_governor. ...
A centrifugal governor controls the speed of an engine by regulating the amount of fuel admitted, so as to maintain a near constant speed whatever the load or fuel supply conditions. ...
Kaplan turbine and electrical generator cut-away view. ...
This article is about the large rocks known as boulders. ...
Look up Fulcrum in Wiktionary, the free dictionary Fulcrum may refer to one of the following. ...
The principle of the lever tells us that the above is in static equilibrium, with all forces balancing, if F1D1 = F2D2. ...
The Industrial Revolution was the golden age of mechanical linkages. Mathematical, engineering and manufacturing advances provided both the need and the ability to create new mechanisms. Many simple mechanisms that seem obvious today required some of the greatest minds of the era to create. Leonhard Euler was one of the first mathematicians to study linkage synthesis, and James Watt worked very hard to invent the Watt linkage to support his steam engine's piston. Chebyshev worked on mechanical linkage design for over thirty years, which led to his work on polynomials2. New linkage inventions, designed by need, were instrumental in cloth making, power conversion and speed regulation. Even the ability of a mechanism to produce accurate linear motion, without a reference guide way, took years to solve. The Industrial Revolution (more correctly, the First Industrial Revolution) was one of the major technological, socioeconomic and cultural changes in the late 18th and early 19th century resulting from the replacement of an economy based on manual labour to one dominated by industry and machine manufacture. ...
It has been suggested that Leonhard Euler/EB1911 biography be merged into this article or section. ...
James Watt James Watt (19 January 1736 – 19 August 1819) was a Scottish inventor and engineer whose improvements to the steam engine were fundamental to the changes wrought by the Industrial Revolution. ...
The parallel motion was a mechanical linkage invented by James Watt in 1784 for his double-acting steam engine. ...
A steam engine is an external combustion heat engine that makes use of the thermal energy that exists in steam, converting it to mechanical work. ...
Pafnuty Lvovich Chebyshev Pafnuty Lvovich Chebyshev (Пафнутий Львович Чебышёв) (May 4, 1821 - November 26, 1894) was a Russian mathematician. ...
In mathematics the Chebyshev polynomials, named after Pafnuty Chebyshev (Пафнутий Чебышёв), are a sequence of orthogonal polynomials which are related to de Moivres formula and which are easily defined recursively, like Fibonacci or Lucas numbers. ...
The locking pliers is an example of a four-bar, one degree of freedom mechanical linkage; or a five-bar, two DOF linkage when the adjustment screw is considered. ...
The power loom was designed in 1787 by Edmund Cartwright and first built in 1785. ...
Scientists, mostly German, Russian and English, have researched this domain over the last 200 years, so that today most traditional analysis or synthesis problems (e.g. planar movement) have been solved (see online libraries under External links). Recently, compliant structures have come to the fore.
Electronic technology has replaced many linkage applications taken for granted today, such as mechanical computation, typewriting and machining. However, modern linkage design continues to advance, and designs that used to occupy an engineer for days are now optimized with a computer in seconds.
Even though servomechanisms with digital control are common, and at first glance easy to use, some motion problems (especially for quick and accurate movements) are still only soluble using linkages and cams. Small R/C servo mechanism 1. ...
Theory The most common linkages have one degree of freedom, meaning that there is one input motion that produces one output motion. Most linkages are also planar, meaning all the motion takes place in one plane. Spatial linkages (non-planar) are more difficult to design and therefore not as common.
Gruebler's equation is used to calculate the degrees of freedom of planar, closed linkages. The number of degrees of freedom of a linkage is also called its mobility:
  = mobility = degrees of freedom = number of links (including a single ground link) = number of one degree of freedom joints (pin or slider joints)
Image File history File links Linkage_mobility. ...
The mobility of hydraulic machinery can easily be identified by counting the number of independently controlled hydraulic cylinders. Hydraulically powered cylinders are visible on this excavator. ...
 Simple linkages are capable of producing complicated motion. Types of common joints: Image File history File links Linkage_path. ...
Image File history File links Linkage_path. ...
- Pin, one DOF rotation. Examples are; bushings, bearings, bolted joints, rivets and hinges.
- Slider, one or two DOF linear motion. Examples are; linear bearings, hydraulic cylinders, rollers and pistons.
- Ball and socket, three DOF rotation, usually restricted to one DOF by other joints in the mechanism.
Designers will synthesize a linkage by starting with the required output motion, mechanical advantage, velocity and acceleration. A type of linkage is chosen and modified to deliver the required performance.
Each link is treated as a vector and the vectors can be combined into a system of equations because they form a loop. The matrix is solved to create a closed form equation that relates input motion to output motion. The same is done for mechanical advantage, or any other important quantity. The equations of motion are differentiated with respect to time to find velocity and acceleration of the mechanism parts. In physics and engineering, mechanical advantage (MA) is the factor by which a machine multiplies the force put into it. ...
In mathematics, the derivative is one of the two central concepts of calculus. ...
Types of linkages Four bar linkages are the simplest closed loop kinematic linkage. They perform a wide variety of motions with a few simple parts. They were also popular in the past due to the ease of calculations, prior to computers, compared to more complicated mechanisms. A four bar linkage or simply a 4-bar or four-bar is the simplest movable linkage. ...
 Types of four bar linkages, s = shortest link, l = longest link
Image File history File links Linkage_four_bar. ...
Image File history File links Linkage_four_bar. ...
Other notable types of linkages;
 A function generator linkage that approximates a parabolic output. - Pantograph (four-bar, two DOF)
- Crank-slider, (four-bar, one DOF)
- Grashof, (four-bar, one DOF) At least one link can rotate 360°
- Five bar linkages often have meshing gears for two of the links, creating a one DOF linkage. They can provide greater power transmission with more design flexibility than four bar linkages.
- Six bar, single DOF linkages offer greater design flexibility than four bar linkages, but require more parts and are more difficult to design.3 ;
- Watt kinematic chain
- Watt I, II
- Stephenson kinematic chain
- Stephenson I, II, III
- Peaucellier-Lipkin linkage, the first linkage to create a straight line output from rotary input; eight-bar, one DOF.
Image File history File links Linkage_function_generator. ...
Image File history File links Linkage_function_generator. ...
A parabola A parabola (from the Greek: παραβολή) is a conic section generated by the intersection of a cone, and a plane tangent to the cone or parallel to some plane tangent to the cone. ...
This page is about the duplication instrument. ...
The locking pliers is an example of a four-bar, one degree of freedom mechanical linkage; or a five-bar, two DOF linkage when the adjustment screw is considered. ...
The Peaucellier-Lipkin linkage (or Peaucellier-Lipkin cell), invented in 1864, was the first linkage capable of transforming rotary motion into perfect straight-line motion. ...
Uses
 A spacial 3DOF linkage for joystick applications. Linkages are primarily used as machine components and tools. Typical examples are automotive suspensions and bolt cutters. The internal combustion engine's piston/rod/crank is a classic four-bar linkage with one degree of freedom. Linkages are often the simplest, least expensive and most efficient mechanism to perform complicated motions. Image File history File links Linkage_spacial_3DOFL.gif linkage, spacial, 3DOF source: Nasa File links The following pages link to this file: Linkage (mechanical) ...
Image File history File links Linkage_spacial_3DOFL.gif linkage, spacial, 3DOF source: Nasa File links The following pages link to this file: Linkage (mechanical) ...
Wind turbines A machine is any mechanical or organic device that transmits or modifies energy to perform or assist in the performance of tasks. ...
A modern hammer is directly descended from ancient hand tools A tool is a device that (most commonly) provides a mechanical advantage in accomplishing a physical task. ...
The front suspension components of a Ford Model T. Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. ...
Bolt cutters A bolt cutter is a scissors-like tool used for cutting heavy chains, bolts and wire mesh. ...
One highly visible application is the windshield wiper: a four bar linkage changes the motor's rotary motion to oscillation. Some wipers also have a second set of four bar linkages to keep the wiper blades oriented correctly as they sweep. Another visible application is heavy equipment which makes extensive use of four and six bar linkages. A windscreen wiper (windshield wiper in North America) is a device used to wipe rain and dirt from a windscreen. ...
An excavator Engineering vehicles are heavy-duty vehicles, specially designed for executing engineering tasks. ...
Spatial linkages are becoming more common due to computer aided design. This article is about computer-aided design. ...
"The 4-Bar Linkage" is an adapted mechanical linkage used on bicycles. With a normal full-suspension bike like an Apollo Creed, the suspension means that the back wheel moves in a very tight arc shape. This means that more power is lost when going uphill. With a bike fitted with a 4-Bar Linkage, like a Diamondback S10, the wheel moves in such a large arc that it is moving almost vertically. This way the power loss is reduced by up to 30%.
References - Erdman, Arthur G.; Sandor, George N. (1984). Mechanism Design: Analysis and Synthesis, Prentice-Hall. ISBN 0-13-572396-5.
- How to Draw a Straight Line, historical discussion of linkage design
- What is a Watt I Linkage?
See also Engineering mechanics is a branch of the physical sciences which looks to understand the actions and reactions of bodies at rest or in motion. ...
A cam is a projecting part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. ...
Wind turbines A machine is any mechanical or organic device that transmits or modifies energy to perform or assist in the performance of tasks. ...
The three-point hitch is a device used on farming tractors used for certain implements. ...
The principle of the lever tells us that the above is in static equilibrium, with all forces balancing, if F1D1 = F2D2. ...
The parallel motion was a mechanical linkage invented by James Watt in 1784 for his double-acting steam engine. ...
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