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ANSI/ASAE S296.4 DEC95 Approved DEC 1995 by American National Standards Institute General Terminology for Traction of Agricultural Tractors, Self-Propelled Implements, and Traction and Transport Devices Proposed by the ASAE Tractive and Transport Efficiency Committee; approved by the ASAE Power and Machinery Division Technical Committee; adopted by ASAE as a Recommendation June 1966; revised February 1970; reconfirmed December 1975; revised and reclas
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  ANSI/ASAE S296.4 DEC95Approved DEC 1995 by American National Standards Institute General Terminology for Traction of Agricultural Tractors,Self-Propelled Implements, and Traction andTransport Devices Proposed by the ASAE Tractive and Transport Efficiency Committee; approved by the ASAE Power and Machinery Division Technical Committee; adopted by ASAE as a Recommendation June 1966; revised February 1970; reconfirmed December 1975; revised and reclassified as a Standard December 1976; reconfirmed December 1981; revised April 1987; reconfirmed December 1991; revised June 1995; approved as an American National Standard December 1995. 1 Purpose and Scope 1.1  The purpose of this terminology is primarily to assist in thestandardized reporting of information on traction and transport devices. Itis possible that data cannot always be reported using this terminology,but in such cases it is recommended that the terms used be clearlydefined. Unless otherwise indicated, all definitions refer to a singletraction or transport device (not the entire vehicle) operating on ahorizontal supporting surface. 2 Normative references ASAE EP285.7 DEC95,  Use of SI (Metric) Units  SAE J708 DEC84,  Agricultural Test Code  SAE J2708 APR93,  Agricultural Tractor Test Code   (OECD) 3 Terminology for all types of traction and transportdevices 1) 3.1 ballast:  Mass that can be added or removed for the purpose ofchanging total load or load distribution. 2) 3.2 flotation:  The ability to resist sinkage into the surface beingtraversed. 3.3 load, dynamic [W d ]:  The total force normal to the undisturbedsupporting surface on which the traction or transport device is operating.The force is the sum of the static load and any load transfer (see figure1). 3.4 load, static [W s ]:  The total force normal to the undisturbedsupporting surface on which the traction or transport device is standingwith zero input torque. 3.5 load transfer [W t ]:  The change in the distribution of the force normalto the undisturbed supporting surface on which the traction or transportdevices are operating as compared to forces for the static vehicle. 3.6 motion resistance of traction device [MR=GT−NT]:  The differencebetween gross traction and net traction; accounts for all energy losses ofa traction device not attributed to slip (see figure 2).  Motion resistance   isthe preferred term; also called  rolling resistance  . 3.7 motion resistance of transport device:  The force required in thedirection of travel to overcome the resistance from the supporting surfaceand the internal resistance of the device.  Motion resistance   is thepreferred term; also called  towing force  . 3.8 motion resistance ratio [   =MR/W d ]:  The ratio of motion resistanceto dynamic load.  Motion resistance   is the preferred term; also called coefficient of rolling resistance   or  coefficient of motion resistance  . 3.9 power, drawbar [DP=P·V]:  The product of drawbar pull and vehiclevelocity in the direction of travel. 3.10 power, input [T·  ]:  The product of input torque and angularvelocity of the driving axle of a traction device. 3.11 power, output [NT·V]:  The product of net traction and velocity ofa traction device. 1) All units should be consistent with ASAE EP285.7. Use of SI (Metric) Units. 2) SAE J708 and SAE J2708 include a similar definition for ballast that does notrecognize transport systems. Figure 1 – Basic velocities and forces on a single wheelwith resultant soil reaction forceFigure 2 – Basic velocities and forces on a single wheel with componentsoil reaction forces (MR and  R v  act as soil-tire interface) 118 ASAE STANDARDS 1998  3.12 pull, drawbar [P]:  The force, in the direction of travel, produced bythe vehicle at the drawbar or hitch.  Drawbar pull   is the preferred term;also called  draft  . 3.13 rolling radius [r o ]:  The distance advanced per revolution of thedriving axle of a traction device under the specified zero condition,divided by 2   . 3.14 sinkage [z]:  Deformation of the supporting surface normal to thedirection of travel of the traction or transport device. Equal to the sum ofthe static sinkage and slip sinkage. 3.15 sinkage, slip:  Sinkage, in addition to static sinkage, that resultsfrom the motion of a traction or transport device. 3.16 sinkage, static:  Sinkage of a stationary traction or transport deviceunder specified zero conditions. 3.17 slip [s]:  See  travel reduction  . 3.18 surface reaction force [R]:  The resultant of all forces acting on thetraction or transport device at the surface-device interface (see figure 1). 3.19 torque, input [T]:  The driving moment applied to the axle of thetraction device (see figure 1). 3.20 traction, gross [GT=T/r 0 =NT+MR]:  The input torque divided by therolling radius. The magnitude depends on the zero condition specified. 3.21 traction, net [NT]:  The force, in the direction of travel, developedby the traction device and transferred to the vehicle (see figure 1). 3.22 traction device:  A device for propelling a vehicle using the reactionforces from the supporting surface; may be a wheel, tire, track, or belt. 3.23 traction ratio, dynamic:  The ratio of drawbar pull to dynamic loadon the vehicle traction devices. 3.24 traction ratio, gross [   g =T/(r o W d )]:  The ratio of gross traction todynamic load.  Gross traction   ratio is the preferred term; also called coefficient of gross traction  . 3.25 tractive ratio, net [   n =NT/W d ]:  The ratio of net traction to dynamicload.  Net traction ratio   is the preferred term; also called  coefficient of net traction  . 3.26 traction ratio, vehicle:  The ratio of drawbar pull to total dynamicload. 3.27 tractive efficiency [TE=NT·V/(T·  )]:  The ratio of output power toinput power. 3.28 transport device:  A device with zero input torque that supports avehicle or implement on a surface during travel over that surface. 3.29 travel ratio:  The ratio of the distance advanced per revolution ofthe traction device under operating conditions, to the distance advancedper revolution under the specified zero condition. 3.30 travel reduction [s]:  One minus travel ratio. The value depends onthe specified zero condition.  Travel reduction   is the preferred term;  slip  and  travel reduction   are sometimes used synonymously and are oftenexpressed in percent. See ASAE S209.5. 3.31 zero condition:  — A traction device supplied with an input torque to propel thedevice across the operating surface or a nondeformable surfacewhile delivering zero net traction; — A traction device supplied with a force at the axle in the directionof travel while supplying zero input torque. The definition based ona deformable surface can sometimes lead to a negative travelreduction on a different operating surface when net traction ispositive; therefore, use of this practice is discouraged. The choiceof zero condition determines the rolling radius, travel reduction,gross traction, and motion resistance and should always be stated. 4 Terminology for track- and belt-type tractiondevices 4.1 angle of approach:  The angle between the supporting surface andthat section of track between the front bogie wheel and the front idler orsprocket. 4.2 angle of departure:  The angle between the supporting surface andthat section of track between the rear bogie wheel and the rear idler ofsprocket. 4.3 grouser:  The portion of the track or belt that extends into the soil forthe purpose of developing traction. Used interchangeably with  lug   and cleat  . 4.4 grouser angle or lug angle:  The angle between the centerline ofthe grouser or lug and the circumferential centerline of the track or belt. 4.5 grouser height or lug height:  The vertical distance from the trackshoe face to the tip of the grouser, or the distance from the belt surfaceto the tip of the lug. 4.6 grouser length:  The distance measured along the grousercenterline between its leading and trailing edges. 4.7 grouser spacing or pitch:  The distance between correspondingpoints on adjacent grousers when the shoe surfaces are in the sameplane. 4.8 lug spacing or pitch:  The distance between corresponding pointson adjacent lugs measured on a flat section of belt. 4.9 nominal ground contact length:  The longitudinal distance betweencenters of front and rearmost sprockets, bogies, or idlers that carry a partof the vehicle vertical load. 4.10 track or belt width:  The overall width of an individual track or belt. 4.11 track or lug pitch:  The distance between corresponding points onadjacent shoes in the same plane. On a belt, it is the lug pitch and is thedistance between corresponding points on adjacent lugs on a flat sectionof belt. 4.12 track width:  The overall width of an individual track. 5 Terminology for tractor tires and rims 5.1 aspect ratio:  The ratio of the section height to the section width ofa tire. 5.2 belt:  The plies of cord material under the tread area of a tire havingthe cords nearly parallel to the centerline of the tire (see figure 3). Thesecords do not tie into the tire beads but furnish circumferential strength forthe tire. 5.3 bias-ply tire:  A tire in which the cords of the body plies rundiagonally from bead to bead. 5.4 breaker plies:  Plies of cord material, in bias-ply tires, that do not tieinto the beads. 5.5 deflection, percent tire:  Tire deflection divided by the portion of thetire section height beyond the rim flange, expressed as a percentage. 5.6 deflection, tire [   =(OD/2)-(SLR)]:  The difference between theunloaded and loaded section heights of a tire at a given load and inflationpressure. 5.7 end-of-lug clearance:  The distance from the trailing side of a lug tothe end of the lug that follows (see figure 3). 5.8 inflation pressure:  For air-filled tires, it is the gauge pressuremeasured with the valve in any position. For tires containing liquid, it isthe gauge pressure measured with an air-water gauge and with the valvein the bottom position. 5.9 low section height tire:  A tire with an aspect ratio less than 0.75.Also called  low profile tire  . 5.10 lug angle:  The average angle between the centerline of the lugface and the circumferential centerline of the tire (see figure 3). 5.11 lug base:  The projected thickness of width of the lug at the pointswhere the projected planes of the leading and trailing sides meet theprojected undertread face (see figure 3, sec. A-A). 5.12 lug bracing angle (for the leading or trailing side of the lug): The angle the lug side makes with a radial line extending from the centerof the wheel through the centerline of the lug (see figure 3, sec. A-A). 5.13 lug face:  The outermost surface of the lug (see figure 3, sec. A-A). ASAE STANDARDS 1998 119  5.14 lug fillet:  The curved section which blends the lug sides into theundertread face (see figure 3, sec. A-A). 5.15 lug height:  The distance measured from the undertread face to thelug face (see figure 3, sec. A-A). 5.16 lug length:  The distance measured from end to end along thecenterline of the lug face (see figure 3). 5.17 lug pitch:  Center-to-center circumferential spacing of similar lugson one side of the centerline of the tire as measured at the lug face (seefigure 3). 5.18 lug side:  The lug surface between the undertread face and the lugface (see figure 3, sec. A-A). 5.19 lug spacing, circumferential:  The distance from the leading sideof a lug to the trailing side of the lug ahead of it, measured parallel to thecenterline of the tire at the lug face (see figure 3). 5.20 lug spacing, perpendicular:  The distance, measuredperpendicularly, from the leading side of a lug to the trailing side of thelug ahead of it at the lug face (see figure 3, sec. A-A). 5.21 lug width:  The width of the lug face as measured perpendicular tothe centerline of the lug face (see figure 3, sec. A-A). 5.22 overall diameter [OD]:  The tire circumference divided by    . Thetire is measured over the lugs in the center plane with the tire mountedon its recommended rim and inflated to the maximum rated inflationpressure in an unloaded condition following a 24-h waiting period (seefigure 4). 5.23 overall width:  The undeflected width of a new tire, includinggrowth resulting from inflation for 24 h, and including protective side ribsand decorations (see figure 4). 5.24 ply rating:  The identification of a given tire with its maximumrecommended load when used in a specific type service. It is an index oftire strength and does not necessarily represent the number of cord pliesin the tire. 5.25 radial-ply tire:  A tire in which the cords of the body plies runsubstantially radially from bead to bead. 5.26 rim diameter:  The nominal diameter at the intersection of the beadseat and vertical portion of the rim flange (see figure 4). 5.27 section height [H]:  The height of a new tire, including normalgrowth caused by inflation following a 24-h waiting period, measuredfrom the rim diameter to the point of maximum radius, on the lug face(see figure 4). 5.28 section width:  The undeflected width of a new tire, includingnormal growth caused by inflation following a 24-h waiting period andincluding normal side walls, but excluding protective side ribs, bars, anddecorations (see figure 4). 5.29 static loaded radius (SLR):  The distance from the center of theaxle to the supporting surface for a tire mounted on an approved rim andcarrying a load at a specific inflation pressure. 5.30 static loaded radius, rated:  The distance from the center of theaxle to the supporting surface for a tire mounted on an approved rim andcarrying the recommended load after being inflated to the correspondingrecommended inflation pressure for 24 h, but without running time on thetire. 3) 5.31 tangential pull value:  Maximum horizontal pull that the tire cancontinously withstand, excluding momentary and occasional peak loads. 5.32 tread radius:  The radius of curvature of the lug faces measured atright angles to the center plane of the tire with the tire mounted on anapproved rim after being inflated to the recommended pressure for 24 h,but without running time on the tire. 5.33 tread width:  The distance from shoulder to shoulder (see figure 3). 5.34 undertread face:  The outermost surface of the rubber on thecarcass where no lugs are located (see figure 3, sec A-A). 3) This is the SLR value published by tire manufacturers. Figure 3 – Tractor tire lug and tread diagramFigure 4 – New tire and rim dimensions 120 ASAE STANDARDS 1998
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