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4x400 Metres Relay
A four-wheel drive, also called 4×4 ("four by four") or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case providing an additional output drive shaft and, in many instances, additional gear ranges. A four-wheel drive vehicle with torque supplied to both axles is described as "all-wheel drive" (AWD). However, "four-wheel drive" typically refers to a set of specific components and functions, and intended off-road application, which generally complies with modern use of the terminology. Definitions Four-wheel-drive systems were developed in many different markets and used in many different vehicle platforms. There is no universally accepted set of terminology that describes the various architectures and functions. The terms used by various manufacturers often reflect marketing rather than engineering considerations or significant technical differen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jeep Wrangler TJ
Jeep is an American automobile brand, now owned by multi-national corporation Stellantis. Jeep has been part of Chrysler since 1987, when Chrysler acquired the Jeep brand, along with other assets, from its previous owner, American Motors Corporation (AMC). Jeep's current product range consists solely of sport utility vehicles—both Crossover (automobile), crossovers and fully off-road vehicle, off-road worthy SUVs and models, including one pickup truck. Previously, Jeep's range included other pick-ups, as well as small vans, and a few Roadster (automobile), roadsters. Some of Jeep's vehicles—such as the Jeep Grand Cherokee, Grand Cherokee—reach into the luxury SUV segment, a market segment the 1963 Jeep Wagoneer (SJ), Wagoneer is considered to have started. Jeep sold 1.4 million SUVs globally in 2016, up from 500,000 in 2008, two-thirds of which in North America, and was Fiat-Chrysler's best selling brand in the U.S. during the first half of 2017. In the U.S. alone, over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dual-motor, Four-wheel-drive Layout
In automotive design, dual-motor, four-wheel-drive layout is mainly used by battery electric vehicles by having two electric motors that each drives the front and rear axle, creating a four-wheel drive layout. This is made possible by the smaller size of electric motors compared to internal combustion engines (ICEs), which in addition are also accompanied by a bulky engine cooling system, allowing it to be fit more versatilely into multiple locations. The use of separate motors for the front and rear drive wheels eliminates the need of a drive shaft that is ubiquitous in four-wheel drive ICE vehicles, freeing up space for bigger battery modules, which are commonly mounted on the chassis floor between the axles. The dual-motor layout is beneficial in re-distributing torque and power to maximize effective propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid bod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dilatant
A dilatant (, ) (also termed shear thickening) material is one in which viscosity increases with the rate of shear strain. Such a ''shear thickening fluid'', also known by the initialism ''STF'', is an example of a non-Newtonian fluid. This behaviour is usually not observed in pure materials, but can occur in suspensions. A dilatant is a non-Newtonian fluid where the shear viscosity increases with applied shear stress. This behavior is only one type of deviation from Newton's law of viscosity, and it is controlled by such factors as particle size, shape, and distribution. The properties of these suspensions depend on Hamaker theory and Van der Waals forces and can be stabilized electrostatically or sterically. Shear thickening behavior occurs when a colloidal suspension transitions from a stable state to a state of flocculation. A large portion of the properties of these systems are due to the surface chemistry of particles in dispersion, known as colloids. This can read ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts. General shear stress The formula to calculate average shear stress or force per unit area is: \tau = ,where is the force applied and is the cross-sectional area. The area involved corresponds to the material face (geometry), face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force. Other forms Wall shear stress Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as:\tau_w := \mu\left.\frac\_,where is the dynamic viscosity, is the flow velocity, and is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscous Coupling Unit
A viscous coupling is a mechanical device which transfers torque and rotation by the medium of a viscosity, viscous fluid. Design Rotary viscous couplings with interleaved, perforated plates and filled with viscous fluids are used in automotive systems to transmit torque. The device consists of a number of circular plates with tabs or perforations, fitted very close to each other in a sealed drum. Alternate plates are connected to a driving Axle, shaft at one end of the assembly and a driven shaft at the other end. The drum is filled with a power-law fluid#Dilatant fluids, dilatant fluid, often silicone-based, to about 80% by volume. When the two sets of plates are rotating in unison, the fluid stays cool and remains liquid. When the plates start rotating at different speeds, the shear effect of the tabs or perforations on the fluid will cause it to heat and become nearly solid because the viscosity of dilatant fluids rapidly increases with shear. The fluid in this state wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplate Clutch
Multiplate multiple electrode aggregometry (MEA) is a test of platelet function in whole blood. The test can be used to diagnose platelet disorders, monitor antiplatelet therapy, and is also investigated as a potential predictor of transfusion requirements and bleeding risk in cardiac surgery. Instrument The Multiplate MEA Analyzer (Roche Diagnostics International Ltd) has 5 channels for simultaneous measurement of several samples or agonists. The instrument detects change in electrical impedance when platelets aggregate on metal electrodes in the test cuvette. Each cuvette contains two pairs of sensor electrodes, each of which measures the change in impedance. The duplicate sensors serve as an integrated quality control, and the analysis is accepted if the correlation coefficient of the measurements is greater than 0.98. The difference of each curve from the mean curve is also calculated, and a difference of less than 20% is accepted. The test cuvettes also contain a teflon c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locking Differential
A locking differential is a mechanical component, commonly used in vehicles, designed to overcome the chief limitation of a standard open Differential (mechanical device), differential by essentially "locking" both wheels on an axle together as if on a common shaft. This forces both wheels to turn in unison, regardless of the traction (or lack thereof) available to either wheel individually. When the differential is unlocked (open differential), it allows each wheel to rotate at different speeds (such as when negotiating a turn), thus avoiding tire scuffing. An open (or unlocked) differential always provides the same torque (rotational force) to each of the two wheels on that axle. Therefore, although the wheels can rotate at different speeds, they apply the same rotational force, even if one is entirely stationary, and the other spinning (equal torque; unequal rotational speed). By contrast, a locked differential forces both left and right wheels on the same axle to rotate at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential Switches
Differential may refer to: Mathematics * Differential (mathematics) comprises multiple related meanings of the word, both in calculus and differential geometry, such as an infinitesimal change in the value of a function * Differential algebra * Differential calculus ** Differential of a function, represents a change in the linearization of a function *** Total differential is its generalization for functions of multiple variables ** Differential (infinitesimal) (e.g. ''dx'', ''dy'', ''dt'' etc.) are interpreted as infinitesimals ** Differential topology * Differential (pushforward) The total derivative of a map between manifolds. * Differential exponent, an exponent in the factorisation of the different ideal * Differential geometry, exterior differential, or exterior derivative, is a generalization to differential forms of the notion of differential of a function on a differentiable manifold * Differential (coboundary), in homological algebra and algebraic topology, one of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ring Gear
An epicyclic gear train (also known as a planetary gearset) is a gear reduction assembly consisting of two gears mounted so that the center of one gear (the "planet") revolves around the center of the other (the "sun"). A carrier connects the centers of the two gears and rotates, to carry the planet gear(s) around the sun gear. The planet and sun gears mesh so that their pitch circles roll without slip. If the sun gear is held fixed, then a point on the pitch circle of the planet gear traces an epicycloid curve. An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of an outer gear ring, or ring gear, sometimes called an ''annulus gear''. Such an assembly of a planet engaging both a sun gear and a ring gear is called a planetary gear train.J. J. Uicker, G. R. Pennock and J. E. Shigley, 2003, ''Theory of Machines and Mechanisms,'' Oxford University Press, New York.B. Paul, 1979, ''Kinematics and Dynamics of Planar Machinery'', Pren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Velocity
In physics, angular velocity (symbol or \vec, the lowercase Greek letter omega), also known as the angular frequency vector,(UP1) is a pseudovector representation of how the angular position or orientation of an object changes with time, i.e. how quickly an object rotates (spins or revolves) around an axis of rotation and how fast the axis itself changes direction. The magnitude of the pseudovector, \omega=\, \boldsymbol\, , represents the '' angular speed'' (or ''angular frequency''), the angular rate at which the object rotates (spins or revolves). The pseudovector direction \hat\boldsymbol=\boldsymbol/\omega is normal to the instantaneous plane of rotation or angular displacement. There are two types of angular velocity: * Orbital angular velocity refers to how fast a point object revolves about a fixed origin, i.e. the time rate of change of its angular position relative to the origin. * Spin angular velocity refers to how fast a rigid body rotates around a f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Driveshaft
A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power, torque, and rotation, usually used to connect other components of a drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them. As torque carriers, drive shafts are subject to torsion and shear stress, equivalent to the difference between the input torque and the load. They must therefore be strong enough to bear the stress, while avoiding too much additional weight as that would in turn increase their inertia. To allow for variations in the alignment and distance between the driving and driven components, drive shafts frequently incorporate one or more universal joints, jaw couplings, or rag joints, and sometimes a splined joint or prismatic joint. History The term ''driveshaft'' first appeared during the mid-19th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Differential (mechanics)
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. A common use of differentials is in motor vehicles, to allow the wheels at each end of a drive axle to rotate at different speeds while cornering. Other uses include clocks and Analog computer, analogue computers. Differentials can also provide a gear ratio between the input and output shafts (called the "axle ratio" or "diff ratio"). For example, many differentials in motor vehicles provide a gearing reduction by having fewer teeth on the pinion than the ring gear. History Milestones in the design or use of differentials include: * 100 BCE–70 BCE: The Antikythera mechanism has been dated to this period. It was discovered in 1902 on a shipwreck by Sponge diving, sponge divers, and modern research suggests that it used a differential gear to determine the angle between the ecliptic positions of the Sun and Moon, and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
