Rolamite is a technology for very low friction bearings developed by Sandia National Laboratories in the 1960s. [1] It is the only elementary machine discovered in the twentieth century and can be used in various ways such as a component in switches, thermostats, valves, pumps, and clutches, among others. [2]
The Rolamite was invented by Sandia engineer Donald F. Wilkes and was patented on June 24, 1969. [3] It was invented while Wilkes was working on a miniature device to detect small changes in the inertia of a small mass. After testing an S-shaped metal foil, which he found to be unstable to support surfaces, the engineer inserted rollers into the S-shaped bends of the band, producing a mechanical assembly that has very low friction in one direction and high stiffness transversely. [1] It became known as Rolamite.
The Rolamite uses a stressed metal band and counter-rotating rollers within an enclosure to create a linear bearing device that loses very little energy to friction. One source claims it is the only basic mechanical invention of the 20th century. [4] Tests by Sandia indicated that Rolamite mechanisms demonstrated friction coefficients as low as 0.0005, an order of magnitude better than ball bearings at the time. There are known Rolamite versions that contain two bands that work in reciprocate parallel for more accurate kinematic transmission at the reverse motion. [5]
A video of a Rolamite in operation, to serve as a warhead safety-switch accelerometer, is available. [6]
A machine is a physical system that uses power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecules, such as molecular machines. 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 ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
Fluid bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly.
A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or the directions of the loads (forces) applied to the parts.
A magnetic bearing is a type of bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear. Magnetic bearings support the highest speeds of any kind of bearing and have no maximum relative speed.
A continuously variable transmission (CVT) is an automated transmission that can change through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant angular velocity while the vehicle moves at varying speeds.
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.
A jewel bearing is a plain bearing in which a metal spindle turns in a jewel-lined pivot hole. The hole is typically shaped like a torus and is slightly larger than the shaft diameter. The jewels are typically made from the mineral corundum, usually either synthetic sapphire or synthetic ruby. Jewel bearings are used in precision instruments where low friction, long life, and dimensional accuracy are important. Their main use is in mechanical watches.
In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements between two concentric, grooved rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding.
A thrust bearing is a particular type of rotary bearing. Like other bearings they permanently rotate between parts, but they are designed to support a predominantly axial load.
A worm drive is a gear arrangement in which a worm meshes with a worm wheel. The two elements are also called the worm screw and worm gear. The terminology is often confused by imprecise use of the term worm gear to refer to the worm, the worm wheel, or the worm drive as a unit.
A linear-motion bearing or linear slide is a bearing designed to provide free motion in one direction. There are many different types of linear motion bearings.
A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter.
A scrollerwheel is a mechanical device composed of a number of rollers and connective bands under tension, which wrap around and weave between the rollers forming a self-supporting cluster possessing a central roller. The cluster of rollers is bound by the connective bands in such a way that the static friction between the rollers and bands prevent the rollers from slipping as they roll and orbit the central roller. Scrollerwheels are related in operational principle to rolamite linear bearings, and like them, they display only rolling friction, and not the kinetic friction inherent in most mechanical bearings.
A roller screw, also known as a planetary roller screw or satellite roller screw, is a low-friction precision screw-type actuator, a mechanical device for converting rotational motion to linear motion, or vice versa. Planetary roller screws are used as the actuating mechanism in many electro-mechanical linear actuators. Due to its complexity the roller screw is a relatively expensive actuator, but may be suitable for high-precision, high-speed, heavy-load, long-life and heavy-use applications.
A timeline of United States inventions (1890–1945) encompasses the ingenuity and innovative advancements of the United States within a historical context, dating from the Progressive Era to the end of World War II, which have been achieved by inventors who are either native-born or naturalized citizens of the United States. Copyright protection secures a person's right to his or her first-to-invent claim of the original invention in question, highlighted in Article I, Section 8, Clause 8 of the United States Constitution which gives the following enumerated power to the United States Congress:
To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.
A spherical roller bearing is a rolling-element bearing that permits rotation with low friction, and permits angular misalignment. Typically these bearings support a rotating shaft in the bore of the inner ring that may be misaligned in respect to the outer ring. The misalignment is possible due to the spherical internal shape of the outer ring and spherical rollers. Despite what their name may imply, spherical roller bearings are not truly spherical in shape. The rolling elements of spherical roller bearings are mainly cylindrical in shape, but have a profile that makes them appear like cylinders that have been slightly over-inflated.
Self-lubricating chains, also referred to as lube-free chains, are commonly found in both roller chain and conveyor chain varieties, with specialty self-lubricating chains also available. These chains utilize a bush made of an oil-impregnated sintered metal or plastic to provide continuous lubrication to the chain during drive, eliminating the need for further lubrication.
A composite bearing is a bearing made from a combination of materials such as a resin reinforced with fibre and this may also include friction reducing lubricants and ingredients.
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