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Wheelspin
A wheelspin occurs when the force delivered to the tire tread exceeds that of available tread-to-surface friction and one or more tires lose traction.This leads the wheels to "spin" and causes the driver to lose control over the tires that no longer have grip on the road surface. Wheelspin can also be done intentionally such as in drifting or doing a burnout. Applications Differentials Standard differentials (also referred to as "open" differentials) always apply equal torque to each wheel. In low traction situations, the total torque delivered to each wheel is limited to the torque that is required to make the wheel with the least traction slip. During a turn, the weight of the vehicle shifts away from the inner radius and to the outer radius, therefore the inner drive-wheel will often lose traction on hard cornering, and especially when accelerating through a curve. Locking differentials and limited slip differentials modify the manner in which torque is distributed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locomotive Wheelslip
{{Unreferenced , date=September 2013 Locomotive wheelslip is an event that affects railway motive power usually when starting from stationary, but can also affect an engine in motion. Overview The greatest effort is required from a locomotive when starting. At this time, if the engineer applies too much power to the wheels (i.e., for a steam locomotive, the engineer opens the regulator too far) the turning force applied to the wheel will greatly exceed the opposing friction force affected by the surface of the rail, and the wheel will turn without being able to move the train forward. If the engineer does not take quick corrective action (i.e. by closing the regulator) the locomotive can end up stationary with its wheels spinning: this can damage both the locomotive drive mechanism, through running too fast, and the rail surface, which, in extreme cases, can be left with a dip where the spin took place. (Such a dip is dangerous if not repaired subsequently.) Some locomotive types ... [...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] |
Traction Control System
A traction control system (TCS), also known as ASR (from german: Antriebsschlupfregelung, lit=drive slippage regulation), is typically (but not necessarily) a secondary function of the electronic stability control (ESC) on production motor vehicles, designed to prevent loss of traction (i.e., wheelspin) of the driven road wheels. TCS is activated when throttle input and engine power and torque transfer are mismatched to the road surface conditions. The intervention consists of one or more of the following: *Brake force applied to one or more wheels *Reduction or suppression of spark sequence to one or more cylinders *Reduction of fuel supply to one or more cylinders *Closing the throttle, if the vehicle is fitted with drive by wire throttle *In turbocharged vehicles, a boost control solenoid is actuated to reduce boost and therefore engine power. Typically, traction control systems share the electrohydraulic brake actuator (which does not use the conventional master cylinder and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into ''static friction'' ("stiction") between non-moving surfaces, and ''kinetic friction'' between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities (see Figure 1). *Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. *Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. *Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. *Internal friction is the force resisting motion between the elements making up a so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traction (engineering)
Traction, or tractive force, is the force used to generate motion between a body and a tangential surface, through the use of dry friction, though the use of shear force of the surface is also commonly used. Traction can also refer to the ''maximum'' tractive force between a body and a surface, as limited by available friction; when this is the case, traction is often expressed as the ratio of the maximum tractive force to the normal force and is termed the ''coefficient of traction'' (similar to coefficient of friction). It is the force which makes an object move over the surface by overcoming all the resisting forces like friction, normal loads(load acting on the tiers in negative 'Z' axis), air resistance, rolling resistance, etc. Definitions Traction can be defined as: In vehicle dynamics, tractive force is closely related to the terms tractive effort and drawbar pull, though all three terms have different definitions. Coefficient of traction The ''coefficient of traction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drifting (motorsport)
Drifting is a driving technique where the driver intentionally oversteers, with loss of traction, while maintaining control and driving the car through the entirety of a corner. The technique causes the rear slip angle to exceed the front slip angle to such an extent that often the front wheels are pointing in the opposite direction to the turn (e.g. car is turning left, wheels are pointed right or vice versa, also known as opposite lock or counter-steering). Drifting is traditionally done by clutch kicking (where the clutch is rapidly disengaged and re-engaged with the intention of upsetting the grip of the rear wheels), then intentionally oversteering and countersteering. This sense of ''drift'' is not to be confused with the ''four wheel drift'', a classic cornering technique established in Grand Prix and sports car racing. As a motoring discipline, drifting competitions were first popularized in Japan in the 1970s and further popularized by the 1995 manga series '' Initial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burnout (vehicle)
A burnout (also known as a peel out, power brake, or brakestand) is the practice of keeping a vehicle stationary and spinning its wheels, the resultant friction causing the tires to heat up and smoke. History The origins of burnouts can be traced to drag racing, where they have a practical purpose: drag racing slicks perform better at higher temperatures, and a burnout is the quickest way to raise tire temperature immediately prior to a race. They also clean the tire of any debris and lay down a layer of rubber by the starting line for better traction. Drag race tracks sometimes use a specially-reserved wet-surface area known as the "water box", because water is poured onto a certain area to reduce the friction to initiate the burnout. This was once called a "bleach box", when bleach was used instead of water; this began in 1969, the year the first burnout was done in NHRA, at the Hot Rod Magazine Championship Drag Races in Riverside, California. Don Garlits was the first to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locking Differentials
A locking differential is a mechanical component, commonly used in vehicles, designed to overcome the chief limitation of a standard open 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 the same speed under nearly all ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limited Slip Differential
A limited-slip differential (LSD) is a type of differential that allows its two output shafts to rotate at different speeds but limits the maximum difference between the two shafts. Limited-slip differentials are often known by the generic trademark Positraction, a brand name owned by General Motors. In an automobile, such limited-slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity. Early history In 1932, Ferdinand Porsche designed a Grand Prix racing car for the Auto Union company. The high power of the design caused one of the rear wheels to experience excessive wheel spin at any speed up to . In 1935, Porsche commissioned the engineering firm ZF to design a limited-slip differential to improve performance. The ZF "sliding pins and cams" became available, and one example was the Type B-70 used during the Second World War in the military VWs ( Kübelwagen and Schwimmwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Understeer And Oversteer
Understeer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Oversteer is what occurs when a car turns (steers) by more than the amount commanded by the driver. Conversely, understeer is what occurs when a car steers less than the amount commanded by the driver. Automotive engineers define understeer and oversteer based on changes in steering angle associated with changes in lateral acceleration over a sequence of steady-state circular turning tests. Car and motorsport enthusiasts often use the terminology more generally in magazines and blogs to describe vehicle response to steering in a variety of maneuvers. Vehicle dynamics terminology Standard terminology used to describe understeer and oversteer are defined by the Society of Automotive Engineers (SAE) in document J670SAE International Surface Vehicle Recommended Practice, "Vehicle Dynamics Terminology", SAE Standard J670, Rev. 2008-01-24 and by the International Organization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rear-wheel Drive
Rear-wheel drive (RWD) is a form of engine and transmission layout used in motor vehicles, in which the engine drives the rear wheels only. Until the late 20th century, rear-wheel drive was the most common configuration for cars. Most rear-wheel drive vehicles feature a longitudinally-mounted engine at the front of the car. Layout The most common layout for a rear-wheel drive car is with the engine and transmission at the front of the car, mounted longitudinally. Other layouts of rear-wheel drive cars include front-mid engine, rear-mid engine, and rear-engine. Some manufacturers, such as Alfa Romeo, Lancia, Porsche (944, 924, 928) and Chevrolet (C5, C6, and C7 Corvettes), place the engine at the front of the car and the transmission at the rear of the car, in order to provide a more balanced weight distribution. This configuration is often referred to as a transaxle since the transmission and axle are one unit. History 1890s to 1960s Many of the cars built in the 19t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
All-wheel Drive
An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand. The most common forms of all-wheel drive are: ;1x1 : All unicycles Reflecting one axle with one wheel capable of being powered. ; 2x2 : Some motorcycles and bikes Reflecting two axles with one wheel on each capable of being powered. ; 4×4 (also, four-wheel drive and 4WD): Reflecting two axles with both wheels on each capable of being powered. ; 6×6 (also, six-wheel drive and 6WD): Reflecting three axles with both wheels on each capable of being powered. ;8×8 (also, eight-wheel drive and 8WD): Reflecting four axles with both wheels on each capable of being powered. Vehicles may be either part-time all-wheel drive or full-time: ;On-demand (also, part-time): One axle is permanently connected to the drive, the other is being connected as needed ;Full-time (also, permanent): All axles are permanently connected, with or without a di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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