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; appr approv oved ed by the ASAE ASAE Powe Powerr and and Machi Machine nery ry Divi Divisi sion on Tech Techni nical cal Committee; adopted by ASAE as a Recommendation June 1966; revised February February 1970; reconfirmed reconfirmed December 1975; revised and reclassified reclassified as a Standard December 1976; reconfirmed December 1981; revised April 1987; reconfirmed December 1991; revised June 1995; approved as an American American National National Standard Standard December December 1995.
1 Purpose and Scope 1.1 The The purpo purpose se of this this termi termino nolo logy gy is prima primari rily ly to assi assist st in the standardized reporting of information on traction and transport devices. It is possible that data cannot always be reported using this terminology, but in such cases it is recommended that the terms used be clearly defined. defined. Unless Unless otherwi otherwise se indica indicated, ted, all definiti definitions ons refer refer to a single single tracti traction on or transp transport ort device device (not (not the entire entire vehicle) vehicle) operati operating ng on a horizontal supporting surface.
2 Normative references ASAE EP285.7 DEC95, Use DEC95, Use of SI (Metric) Units SAE J708 DEC84, Agricultural DEC84, Agricultural Test Code SAE J2708 APR93, Agricultural APR93, Agricultural Tractor Test Code (OECD) (OECD)
3 Terminology for all types of traction and transport devices1) 3.1 ballast: Mass that can be added or removed for the purpose of changing total load or load distribution.2) 3.2 flotation: The abil abilitityy to resi resist st sinka sinkage ge into into the the surfa surface ce being being traversed. 3.3 load, dynamic [Wd]: The total total force force normal normal to the undisturb undisturbed ed supporting supporting surface on which the traction or transport transport device is operating. operating. The force is the sum of the static load and any load transfer (see figure 1).
Figure 1 – Basic velocities and forces on a single wheel with resultant soil reaction force
3.8 motion resistance ratio [ =MR/W =MR/Wd]: The ]: The ratio of motion resistance resistance to dynamic load. Motion resistance is is the preferred term; also called coefficient coefficient of rolling resistance or or coefficient of motion resistance . 3.9 power, drawbar [DP=P·V]: The [DP=P·V]: The product of drawbar pull and vehicle velocity in the direction of travel. 3.10 power, input [T·]: The product product of input input torque torque and angular angular velocity of the driving axle of a traction device. 3.11 power, output [NT·V]: The [NT·V]: The product of net traction and velocity of a traction device.
3.4 3.4 load, load, stat static ic [Ws]: The total total forc forcee norm normal al to the the undis undistu turb rbed ed supporting surface on which the traction or transport device is standing with zero input torque. 3.5 load transfer [Wt]: The ]: The change in the distribution of the force normal to the undisturbed supporting surface on which the traction or transport devices are operating as compared to forces for the static vehicle. 3.6 motion resistance of traction device [MR=GT−NT]: The [MR=GT−NT]: The difference between gross traction traction and net traction; accounts for all energy losses of a traction device not attributed to slip (see figure 2). Motion 2). Motion resistance is is the preferred term; also called called rolling resistance . 3.7 motion resistance of transport device: The device: The force required in the direction of travel to overcome the resistance from the supporting surface and the intern internal al resista resistance nce of the device. device. Motion resistance resistance is the preferred term; also called towing called towing force . 1)
All units should be consistent with ASAE EP285.7. Use of SI (Metric) Units. SAE J708 and SAE J2708 include a similar definition for ballast that does not recognize transport systems.
2)
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Figure Figure 2 – Basic velocities velocities and forces forces on a single wheel wheel with component component soil reaction forces (MR and R and R v act as soil-tire interface)
ASAE STANDARDS 1998
3.12 pull, drawbar [P]: The force, in the direction of travel, produced by the vehicle at the drawbar or hitch. Drawbar pull is the preferred term; also called draft . 3.13 rolling radius [ro]: The distance advanced per revolution of the driving axle of a traction device under the specified zero condition, divided by 2 . 3.14 sinkage [z]: Deformation of the supporting surface normal to the direction of travel of the traction or transport device. Equal to the sum of the static sinkage and slip sinkage. 3.15 sinkage, slip: Sinkage, in addition to static sinkage, that results from the motion of a traction or transport device. 3.16 sinkage, static: Sinkage of a stationary traction or transport device under specified zero conditions. 3.17 slip [s]: See travel reduction . 3.18 surface reaction force [R]: The resultant of all forces acting on the traction or transport device at the surface-device interface (see figure 1). 3.19 torque, input [T]: The driving moment applied to the axle of the traction device (see figure 1). 3.20 traction, gross [GT=T/r0=NT+MR]: The input torque divided by the rolling radius. The magnitude depends on the zero condition specified. 3.21 traction, net [NT]: The force, in the direction of travel, developed by the traction device and transferred to the vehicle (see figure 1). 3.22 traction device: A device for propelling a vehicle using the reaction forces from the supporting surface; may be a wheel, tire, track, or belt. 3.23 traction ratio, dynamic: The ratio of drawbar pull to dynamic load on the vehicle traction devices. 3.24 traction ratio, gross [ g=T/(roWd)]: The ratio of gross traction to dynamic load. Gross traction ratio is the preferred term; also called coefficient of gross traction . 3.25 tractive ratio, net [ n=NT/Wd]: The ratio of net traction to dynamic load. 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 dynamic load. 3.27 tractive efficiency [TE=NT·V/(T·)]: The ratio of output power to input power. 3.28 transport device: A device with zero input torque that supports a vehicle or implement on a surface during travel over that surface. 3.29 travel ratio: The ratio of the distance advanced per revolution of the traction device under operating conditions, to the distance advanced per revolution under the specified zero condition. 3.30 travel reduction [s]: One minus travel ratio. The value depends on the specified zero condition. Travel reduction is the preferred term; slip and travel reduction are sometimes used synonymously and are often expressed in percent. See ASAE S209.5. 3.31 zero condition: — A traction device supplied with an input torque to propel the device across the operating surface or a nondeformable surface while delivering zero net traction; — A traction device supplied with a force at the axle in the direction of travel while supplying zero input torque. The definition based on a deformable surface can sometimes lead to a negative travel reduction on a different operating surface when net traction is positive; therefore, use of this practice is discouraged. The choice of 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 traction devices 4.1 angle of approach: The angle between the supporting surface and that section of track between the front bogie wheel and the front idler or sprocket. ASAE STANDARDS 1998
4.2 angle of departure: The angle between the supporting surface and that section of track between the rear bogie wheel and the rear idler of sprocket. 4.3 grouser: The portion of the track or belt that extends into the soil for the purpose of developing traction. Used interchangeably with lug and cleat . 4.4 grouser angle or lug angle: The angle between the centerline of the grouser or lug and the circumferential centerline of the track or belt. 4.5 grouser height or lug height: The vertical distance from the track shoe face to the tip of the grouser, or the distance from the belt surface to the tip of the lug. 4.6 grouser length: The distance measured along the grouser centerline between its leading and trailing edges. 4.7 grouser spacing or pitch: The distance between corresponding points on adjacent grousers when the shoe surfaces are in the same plane. 4.8 lug spacing or pitch: The distance between corresponding points on adjacent lugs measured on a flat section of belt. 4.9 nominal ground contact length: The longitudinal distance between centers of front and rearmost sprockets, bogies, or idlers that carry a part of 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 on adjacent shoes in the same plane. On a belt, it is the lug pitch and is the distance between corresponding points on adjacent lugs on a flat section of 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 of a tire. 5.2 belt: The plies of cord material under the tread area of a tire having the cords nearly parallel to the centerline of the tire (see figure 3). These cords do not tie into the tire beads but furnish circumferential strength for the tire. 5.3 bias-ply tire: A tire in which the cords of the body plies run diagonally from bead to bead. 5.4 breaker plies: Plies of cord material, in bias-ply tires, that do not tie into the beads. 5.5 deflection, percent tire: Tire deflection divided by the portion of the tire section height beyond the rim flange, expressed as a percentage. 5.6 deflection, tire [ =(OD/2)-(SLR)]: The difference between the unloaded and loaded section heights of a tire at a given load and inflation pressure. 5.7 end-of-lug clearance: The distance from the trailing side of a lug to the end of the lug that follows (see figure 3). 5.8 inflation pressure: For air-filled tires, it is the gauge pressure measured with the valve in any position. For tires containing liquid, it is the gauge pressure measured with an air-water gauge and with the valve in 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 lug face and the circumferential centerline of the tire (see figure 3). 5.11 lug base: The projected thickness of width of the lug at the points where the projected planes of the leading and trailing sides meet the projected 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 center of 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). 119
Figure 3 – Tractor tire lug and tread diagram
5.14 lug fillet: The curved section which blends the lug sides into the undertread face (see figure 3, sec. A-A). 5.15 lug height: The distance measured from the undertread face to the lug face (see figure 3, sec. A-A). 5.16 lug length: The distance measured from end to end along the centerline of the lug face (see figure 3). 5.17 lug pitch: Center-to-center circumferential spacing of similar lugs on one side of the centerline of the tire as measured at the lug face (see figure 3). 5.18 lug side: The lug surface between the undertread face and the lug face (see figure 3, sec. A-A). 5.19 lug spacing, circumferential: The distance from the leading side of a lug to the trailing side of the lug ahead of it, measured parallel to the centerline of the tire at the lug face (see figure 3). 5.20 lug spacing, perpendicular: The distance, measured perpendicularly, from the leading side of a lug to the trailing side of the lug 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 to the centerline of the lug face (see figure 3, sec. A-A). 5.22 overall diameter [OD]: The tire circumference divided by . The tire is measured over the lugs in the center plane with the tire mounted on its recommended rim and inflated to the maximum rated inflation pressure in an unloaded condition following a 24-h waiting period (see figure 4).
5.23 overall width: The undeflected width of a new tire, including growth resulting from inflation for 24 h, and including protective side ribs and decorations (see figure 4). 5.24 ply rating: The identification of a given tire with its maximum recommended load when used in a specific type service. It is an index of tire strength and does not necessarily represent the number of cord plies in the tire. 5.25 radial-ply tire: A tire in which the cords of the body plies run substantially radially from bead to bead. 5.26 rim diameter: The nominal diameter at the intersection of the bead seat and vertical portion of the rim flange (see figure 4). 5.27 section height [H]: The height of a new tire, including normal growth caused by inflation following a 24-h waiting period, measured from 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, including normal growth caused by inflation following a 24-h waiting period and including normal side walls, but excluding protective side ribs, bars, and decorations (see figure 4). 5.29 static loaded radius (SLR): The distance from the center of the axle to the supporting surface for a tire mounted on an approved rim and carrying a load at a specific inflation pressure. 5.30 static loaded radius, rated: The distance from the center of the axle to the supporting surface for a tire mounted on an approved rim and carrying the recommended load after being inflated to the corresponding recommended inflation pressure for 24 h, but without running time on the tire.3) 5.31 tangential pull value: Maximum horizontal pull that the tire can continously withstand, excluding momentary and occasional peak loads. 5.32 tread radius: The radius of curvature of the lug faces measured at right angles to the center plane of the tire with the tire mounted on an approved 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 the carcass where no lugs are located (see figure 3, sec A-A). 3)
This is the SLR value published by tire manufacturers.
Figure 4 – New tire and rim dimensions
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ASAE STANDARDS 1998
