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.
a physical process in which a tangential force is transmitted across an interface between two bodies through dry friction or an intervening fluid film resulting in motion, stoppage or the transmission of power.
— Mechanical Wear Fundamentals and Testing, Raymond George Bayer[5]
Diagram of the longitudinal coefficient of adhesion (fx) in function of the speed and the weather conditions for the asphalt: A) dry asphalt B) Asphalt drainage in wet conditions C) Asphalt in wet conditions D) Snow E) IceChange cross tack (Fy) average during the seasons (represented numerically from 1 to 12) and with different road surfaces. A) Hot Rolled Asphalt B) Gravel C) Quartzite D) Conglomerate cement E) mastic asphalt F) Gravel sedimentary (unbound)
The coefficient of traction is defined as the usable force for traction divided by the weight on the running gear (wheels, tracks etc.)[6][7] i.e.: usable traction = coefficient of traction × normal force.
Factors affecting coefficient of tractionedit
Traction between two surfaces depends on several factors:
Contaminants at the material boundary including lubricants and adhesives.
Relative motion of tractive surfaces - a sliding object (one in kinetic friction) has less traction than a non-sliding object (one in static friction).
Direction of traction relative to some coordinate system - e.g., the available traction of a tire often differs between cornering, accelerating, and braking.[8]
For low-friction surfaces, such as off-road or ice, traction can be increased by using traction devices that partially penetrate the surface; these devices use the shear strength of the underlying surface rather than relying solely on dry friction (e.g., aggressive off-road tread or snow chains)....
In the design of wheeled or tracked vehicles, high traction between wheel and ground is more desirable than low traction, as it allows for higher acceleration (including cornering and braking) without wheel slippage. One notable exception is in the motorsport technique of drifting, in which rear-wheel traction is purposely lost during high speed cornering.
Other designs dramatically increase surface area to provide more traction than wheels can, for example in continuous track and half-track vehicles.[citation needed] A tank or similar tracked vehicle uses tracks to reduce the pressure on the areas of contact. A 70-ton M1A2 would sink to the point of high centering if it used round tires. The tracks spread the 70 tons over a much larger area of contact than tires would and allow the tank to travel over much softer land.
In some applications, there is a complicated set of trade-offs in choosing materials. For example, soft rubbers often provide better traction but also wear faster and have higher losses when flexed—thus reducing efficiency. Choices in material selection may have a dramatic effect. For example: tires used for track racing cars may have a life of 200 km, while those used on heavy trucks may have a life approaching 100,000 km. The truck tires have less traction and also thicker rubber.
Traction also varies with contaminants. A layer of water in the contact patch can cause a substantial loss of traction. This is one reason for grooves and siping of automotive tires.
The traction of trucks, agricultural tractors, wheeled military vehicles, etc. when driving on soft and/or slippery ground has been found to improve significantly by use of Tire Pressure Control Systems (TPCS). A TPCS makes it possible to reduce and later restore the tire pressure during continuous vehicle operation. Increasing traction by use of a TPCS also reduces tire wear and ride vibration.[9]
^Laughery, Sean; Gerhart, Grant; Muench., Paul (2000), Evaluating Vehicle Mobility Using Bekker's Equations(PDF), U.S. Army TARDEC, (PDF) from the original on July 5, 2019
^Burch, Deryl (1997). "Usable Power". Estimating Excavation. Craftsman Book Co. p. 215. ISBN0-934041-96-2.
^"Friction". hyperphysics.phy-astr.gsu.edu. Retrieved 20 April 2018.
^Abhishek. "Metro Train Simulation". metrotrainsimulation.com. Retrieved 20 April 2018.
^Bayer, Raymond George (22 April 2004). "Terminology and Classifications". Mechanical Wear Fundamentals and Testing. CRC Press. p. 3. ISBN0-8247-4620-1.
^Schexnayder, Clifford J.; Mayo, Richard (2003). Construction Management Fundamentals. McGraw-Hill Professional. p. 346. ISBN0-07-292200-1.
^Wong, Jo Yung (20 March 2001). "4.1.3 Coefficient of Traction". Theory of ground vehicles. p. 317. ISBN0-471-35461-9.
^Munro, Ron; MacCulloch, Frank (February 2008). "Tyre Pressure Control on Timber Haulage Vehicles: Some observations on a trial in Highland, Scotland" (PDF). ROADEX III Northern Periphery. Retrieved 20 April 2018.
November 16, 2023
traction, mechanics, traction, traction, force, tractive, force, force, used, generate, motion, between, body, tangential, surface, through, either, friction, shear, force, important, applications, vehicles, tractive, effort, traction, also, refer, maximum, tr. Traction traction force or tractive force is a force used to generate motion between a body and a tangential surface through the use of either dry friction or shear force 1 2 3 4 It has important applications in vehicles as in tractive effort 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 Contents 1 Definitions 2 Coefficient of traction 2 1 Factors affecting coefficient of traction 2 2 Traction coefficient in engineering design 3 See also 4 ReferencesDefinitions editTraction can be defined as a physical process in which a tangential force is transmitted across an interface between two bodies through dry friction or an intervening fluid film resulting in motion stoppage or the transmission of power Mechanical Wear Fundamentals and Testing Raymond George Bayer 5 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 editSee also Coefficient of friction nbsp Diagram of the longitudinal coefficient of adhesion fx in function of the speed and the weather conditions for the asphalt A dry asphalt B Asphalt drainage in wet conditions C Asphalt in wet conditions D Snow E Ice nbsp Change cross tack Fy average during the seasons represented numerically from 1 to 12 and with different road surfaces A Hot Rolled Asphalt B Gravel C Quartzite D Conglomerate cement E mastic asphalt F Gravel sedimentary unbound The coefficient of traction is defined as the usable force for traction divided by the weight on the running gear wheels tracks etc 6 7 i e usable traction coefficient of traction normal force Factors affecting coefficient of traction edit Traction between two surfaces depends on several factors Material composition of each surface Macroscopic and microscopic shape texture macrotexture and microtexture Normal force pressing contact surfaces together Contaminants at the material boundary including lubricants and adhesives Relative motion of tractive surfaces a sliding object one in kinetic friction has less traction than a non sliding object one in static friction Direction of traction relative to some coordinate system e g the available traction of a tire often differs between cornering accelerating and braking 8 For low friction surfaces such as off road or ice traction can be increased by using traction devices that partially penetrate the surface these devices use the shear strength of the underlying surface rather than relying solely on dry friction e g aggressive off road tread or snow chains Traction coefficient in engineering design edit This section needs additional citations for verification Please help improve this article by adding citations to reliable sources in this section Unsourced material may be challenged and removed April 2009 Learn how and when to remove this template message In the design of wheeled or tracked vehicles high traction between wheel and ground is more desirable than low traction as it allows for higher acceleration including cornering and braking without wheel slippage One notable exception is in the motorsport technique of drifting in which rear wheel traction is purposely lost during high speed cornering Other designs dramatically increase surface area to provide more traction than wheels can for example in continuous track and half track vehicles citation needed A tank or similar tracked vehicle uses tracks to reduce the pressure on the areas of contact A 70 ton M1A2 would sink to the point of high centering if it used round tires The tracks spread the 70 tons over a much larger area of contact than tires would and allow the tank to travel over much softer land In some applications there is a complicated set of trade offs in choosing materials For example soft rubbers often provide better traction but also wear faster and have higher losses when flexed thus reducing efficiency Choices in material selection may have a dramatic effect For example tires used for track racing cars may have a life of 200 km while those used on heavy trucks may have a life approaching 100 000 km The truck tires have less traction and also thicker rubber Traction also varies with contaminants A layer of water in the contact patch can cause a substantial loss of traction This is one reason for grooves and siping of automotive tires The traction of trucks agricultural tractors wheeled military vehicles etc when driving on soft and or slippery ground has been found to improve significantly by use of Tire Pressure Control Systems TPCS A TPCS makes it possible to reduce and later restore the tire pressure during continuous vehicle operation Increasing traction by use of a TPCS also reduces tire wear and ride vibration 9 See also editAnti lock braking system Equilibrium tide Friction Force physics Karl A Grosch Rail adhesion Road slipperiness Sandbox locomotive Tribology Weight transferReferences edit Laughery Sean Gerhart Grant Muench Paul 2000 Evaluating Vehicle Mobility Using Bekker s Equations PDF U S Army TARDEC archived PDF from the original on July 5 2019 Burch Deryl 1997 Usable Power Estimating Excavation Craftsman Book Co p 215 ISBN 0 934041 96 2 Friction hyperphysics phy astr gsu edu Retrieved 20 April 2018 Abhishek Metro Train Simulation metrotrainsimulation com Retrieved 20 April 2018 Bayer Raymond George 22 April 2004 Terminology and Classifications Mechanical Wear Fundamentals and Testing CRC Press p 3 ISBN 0 8247 4620 1 Schexnayder Clifford J Mayo Richard 2003 Construction Management Fundamentals McGraw Hill Professional p 346 ISBN 0 07 292200 1 Wong Jo Yung 20 March 2001 4 1 3 Coefficient of Traction Theory of ground vehicles p 317 ISBN 0 471 35461 9 J670 Vehicle Dynamics Terminology SAE Munro Ron MacCulloch Frank February 2008 Tyre Pressure Control on Timber Haulage Vehicles Some observations on a trial in Highland Scotland PDF ROADEX III Northern Periphery Retrieved 20 April 2018 Retrieved from https en wikipedia org w index php title Traction mechanics amp oldid 1183044303, wikipedia, wiki, book, books, library,
