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Rolled
Rolling is a type of motion that combines rotation (commonly, of an axially symmetric object) and translation of that object with respect to a surface (either one or the other moves), such that, if ideal conditions exist, the two are in contact with each other without sliding. Rolling where there is no sliding is referred to as ''pure rolling''. By definition, there is no sliding when there is a frame of reference in which all points of contact on the rolling object have the same velocity as their counterparts on the surface on which the object rolls; in particular, for a frame of reference in which the rolling plane is at rest (see animation), the instantaneous velocity of all the points of contact (for instance, a generating line segment of a cylinder) of the rolling object is zero. In practice, due to small deformations near the contact area, some sliding and energy dissipation occurs. Nevertheless, the resulting rolling resistance is much lower than sliding friction, and thu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Motor
An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to generate Laplace force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates in reverse, converting mechanical energy into electrical energy. Electric motors can be powered by direct current (DC) sources, such as from batteries or rectifiers, or by alternating current (AC) sources, such as a power grid, Inverter (electrical), inverters or electrical generators. Electric motors may also be classified by considerations such as power source type, construction, application and type of motion output. They can be brushed motor, brushed or brushless motor, brushless, single-phase electric power, single-phase, two-phase electric power, two-phase, or three-phase electric p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dice
A die (: dice, sometimes also used as ) is a small, throwable object with marked sides that can rest in multiple positions. Dice are used for generating random values, commonly as part of tabletop games, including dice games, board games, role-playing games, and games of chance. A traditional die is a cube with each of its six faces marked with a different number of dots ( pips) from one to six. When thrown or rolled, the die comes to rest showing a random integer from one to six on its upper surface, with each value being equally likely. Dice may also have other polyhedral or irregular shapes, may have faces marked with numerals or symbols instead of pips and may have their numbers carved out from the material of the dice instead of marked on it. Loaded dice are specifically designed or modified to favor some results over others, for cheating or entertainment purposes. History Dice have been used since before recorded history, and their origin is uncertain. It is hypoth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bearing (mechanical)
A ball bearing 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. The term "bearing" is derived from the verb " to bear"; a bearing being a machine element that allows one part to bear (i.e., to support) another. The simplest bearings are bearing surfaces, cut or formed into a part, with varying degrees of control over the form, size, roughness, and location of the surface. Other bearings are separate devices installed into a machine or mach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Vehicle
A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered vehicles (e.g. bicycles, tricycles, velomobiles), animal-powered transports (e.g. horse-drawn carriages/wagons, ox carts, dog sleds), motor vehicles (e.g. motorcycles, cars, trucks, buses, mobility scooters) and railed vehicles (trains, trams and monorails), but more broadly also includes cable transport ( cable cars and elevators), watercraft (ships, boats and underwater vehicles), amphibious vehicles (e.g. screw-propelled vehicles, hovercraft, seaplanes), aircraft (airplanes, helicopters, gliders and aerostats) and space vehicles (spacecraft, spaceplanes and launch vehicles). This article primarily concerns the more ubiquitous land vehicles, which can be broadly classified by the type of contact interface with the ground: wheels, tracks, rails or skis, as well as the non-contact technolog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rolling Cone Motion
Rolling cone motion is the Rolling, rolling motion generated by a cone (geometry), cone rolling over another cone. In rolling cone motion, at least one of the cones is convex body, convex, while the other cone may be either convex, or concave, or a flat surface (a flat surface can be regarded as a special case of a cone whose Apex (geometry), apex angle equals \pi). The distinguishing characteristic of a rolling cone, in relation to other axial symmetry, axially symmetrical rollers (Cylinder (geometry), cylinder, sphere, Disk (mathematics), round disk), is that while rolling on a flat surface, the cone's center of gravity performs a circular motion rather than a linear motion, linear one. Another unique characteristic is that one of its points (its apex) is at rest throughout the entire motion. Kinematics The motion of a rolling cone can be described as a Superposition principle, superposition of a rotation, rotational motion of the cone around its axis of symmetry, and a rotary mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wheel
A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machines. Wheels, in conjunction with axles, allow heavy objects to be moved easily facilitating movement or transportation while supporting a load, or performing labor in machines. Wheels are also used for other purposes, such as a ship's wheel, steering wheel, potter's wheel, and flywheel. Common examples can be found in transport applications. A wheel reduces friction by facilitating motion by rolling together with the use of axles. In order for a wheel to rotate, a Moment (physics), moment must be applied to the wheel about its axis, either by gravity or by the application of another external force or torque. Terminology The English word '':wikt:wheel, wheel'' comes from the Old English word , from Proto-Germanic language, Proto-Germanic , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Developable Surface
In mathematics, a developable surface (or torse: archaic) is a smooth surface with zero Gaussian curvature. That is, it is a surface that can be flattened onto a plane without distortion (i.e. it can be bent without stretching or compression). Conversely, it is a surface which can be made by transforming a plane (i.e. "folding", "bending", "rolling", "cutting" and/or "gluing"). Because of these properties, developable surfaces are widely used in the design and fabrication of items to be made from sheet materials, ranging from textiles to sheet metal such as ductwork to shipbuilding. In three dimensions all developable surfaces are ruled surfaces (but not vice versa). There are developable surfaces in four-dimensional space which are not ruled. The envelope of a single parameter family of planes is called a developable surface. Particulars The developable surfaces which can be realized in three-dimensional space include: *Cylinders and, more generally, the "generalized ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axle
An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing (mechanical), bearings or Bushing (bearing), bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a ''spindle (tool), spindle''. Terminology On cars and trucks, several senses of the word ''axle'' occur in casual usage, referring to the shaft itself, its housing, or simply any transverse pair of wheels. Strictly speaking, a shaft that rotates with the wheel, being either Bolt (fastener), bolted or rotating spline, splined in fixed relation to it, is called an ''axle'' or ''axle shaft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rolling Resistance
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the Motion (physics), motion when a body (such as a ball, tire, or wheel) Rolling, rolls on a surface. It is mainly caused by Plasticity (physics), non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc., is recovered when the pressure is removed. Two forms of this are hysteresis losses (see rolling resistance#Primary cause, below), and permanent plastic deformation, (plastic) deformation of the object or the surface (e.g. soil). Note that the frictional contact mechanics, slippage between the wheel and the surface also results in energy dissipation. Although some researchers have included this term in rolling resistance, some suggest that this dissipation term should be treated separately from rolling resistance because it is due to the applied torque to the wheel and the resultant slip between the wheel and ground, which is called ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sphericon
In solid geometry, the sphericon is a solid that has a continuous developable surface with two Congruence (geometry), congruent, semicircle, semi-circular edges, and four Vertex (geometry), vertices that define a square. It is a member of a special family of Developable roller, rollers that, while being rolled on a flat surface, bring all the points of their surface to contact with the surface they are rolling on. It was discovered independently by carpenter Colin Roberts (who named it) in the UK in 1969, by dancer and sculptor Alan Boeding of MOMIX in 1979, and by inventor David Hirsch, who patented it in Israel in 1980. Construction The sphericon may be constructed from a bicone (a double cone (geometry), cone) with an apex (geometry), apex angle of 90 degrees, by splitting the bicone along a plane through both apexes, rotating one of the two halves by 90 degrees, and reattaching the two halves. Alternatively, the surface of a sphericon can be formed by cutting and gluing a pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rolling-element Bearing
In mechanical engineering, a rolling-element bearing, also known as a rolling bearing,ISO 15 is a bearing (mechanical), bearing which carries a load by placing rolling elements (such as balls, cylinders, or cones) between two concentric, Groove (engineering), grooved rings called Race (bearing), races. The relative motion of the races causes the rolling elements to rolling, roll with very little rolling resistance and with little sliding (motion), sliding. One of the earliest and best-known rolling-element bearings is a set of logs laid on the ground with a large stone block on top. As the stone is pulled, the logs roll along the ground with little sliding friction. As each log comes out the back, it is moved to the front where the block then rolls onto it. It is possible to imitate such a bearing by placing several pens or pencils on a table and placing an item on top of them. See "bearing (mechanical), bearings" for more on the historical development of bearings. A rolling el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Square Wheel
A square wheel is a wheel that, instead of being circle, circular, has the shape of a square (geometry), square. While literal square wheels exist, a more common use is as an idiom meaning stereotypically bad or naive engineering (see reinventing the wheel). A square wheel can roll smoothly if the ground consists of evenly shaped inverted catenary, catenaries of the right size and curvature. A different type of square-wheeled vehicle was invented in 2006 by Jason Winckler of Global Composites, Inc. in the United States. This has square wheels, linked together and offset by 22.5°, rolling on a flat surface. The prototype appears ungainly, but the inventor proposes that the system may be useful in microscopic-sized machines (Microelectromechanical systems, MEMS). In 1997 Macalester College mathematics professor Stan Wagon constructed the first prototype of a catenary tricycle. An improved model made out of modern materials was built when the original vehicle wore out in April, 200 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
