Although the new method can be derived from a modification of the shear stress equations, it does not use shear stress explicitly. Tractive effort or tractive force is measured in kilonewtons kn or pounds force lbf where 1 kn 228. Tractive effort curves show how much force the wheels can push forward on the rails with for any given speed. Tractive effort versus horsepower trains magazine trains. From newtons second law using the equation above you can work out the equivalent accelerations to each tractive effort. Pound force applied to the rear coupler to pull a train. Tractive effort is the force needed to simply move the train. A 4,000 hp sd70mac of 20 years later produces 86,000 lbs maximum db force. As used in mechanical engineering, the term tractive force can either refer to the total traction a. Take one example i have one vehicle which has weight of 500kg. Due to the relationship between power p, velocity v and force f, described as. Pdf vehicle tractive force prediction with robust and windupstable. Tractive force is nothing but the net force present at wheels. Above is a tractive effort curve typical of a new electric train.
Tractive effort and resistance to motion tractive effort resistance to motion i have extended the speed range on the graph to show the point where the resistance to motion gets larger than the tractive effort. The tractive force between a car wheel and the surface can be expressed as. Both can be affected by the softness of the soil surface and are usually determined on a hard surface. Total motor limited tractive force from from both front wheels, ffwmax n. Horsepower in automotive terms is the application of a force at a certain speed. Acceleration is a measure of how quickly you are gaining or losing speed. Jan perner transport faculty, university of pardubice, studentska 95, 532 10. What is difference between tractive force and tractive effort. In railway engineering, the term tractive effort is often used synonymously with tractive force to describe the pulling or pushing capability of a locomotive. Tractive force is the propulsive force that drive wheels or tracks apply to the ground to move a vehicle along a path, whether it is a road, a railroad track, or soft earth. Army corps of engineers riprap design for flood channels. The speed at which both forces are equal is the maximum speed the train can get to on a flat piece of track.
The acceleration force is a function of the mass of the vehicle. Ahmed abdelrahim available tractive effort tractive effort determined by. Calculation of locomotive traction force in transient rolling contact. The total axle torque is tractive effort times the wheel radius.
Department of agriculture usda prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where. The following state equation is obtained if the tractive force f changes as a step function. F traction effort or force acting on the wheel from the surface n, lb f. Tractive effort te and tractive resistance tr tractive effort te. This calculator can be used to calculate the resulting force in a toggle joint with arms with equal lengths. Tireground adhesion and maximum tractive effort the slip, s, of a tire is usually defined as where v is the translatory speed of the tire center. This calculator will determine the forces, momentum and physics of a four wheeled vehical driving over various conditions. For steam locomotives, tractive effort was usually the limitting factor in the size of the train it could pull. When a vehicle is moving up a gradient, the normal force p, in equation 4. Understanding torque and horsepower with tractive force. Tractive effort and tractive resistance c12 springerlink. In other words, it is the sum of the tractive force and rolling effort on the road surface. A number that relates to a tractive effort on a dc motor locomotive that the traction motor can obtain indefinitely without overheating. Employ a balance between the shear force mobilizing the sediment and the resisting force depending on the material.
Therefore, tractive effort was more important than horsepower for steam locomotives. Fa m a 3 m gvw g 4 fa acceleration force m mass of the vehicle g acceleration due to gravity9. The velocity of a locomotive depends on two forces the. At very slow yard speeds only 2 to 3 pounds is needed while increasing to about 5 pounds at higher speeds. Available tractive effort road vehicle performance. The wheel torque calculated in step five is the total. An amount of torque distributed to the wheel from differential divided by wheel radius is the tractive effort an. Measurement of tractive force in the creep region and maximum. A 3,000 hp sd402 may produce a maximum of 10,000 lbs of db force for each axle or 60,000 lbs total. In this case, the liquid is storm water and the boundary is the channel surface.
Car vehicle driving up a slope equation and calculator. Tractive efficiency te, usually thought of as percent but used as a ratio in this paper. I have calculate the tractional force required to move the vehicle. The calculator can be used for imperial and metric units as long as the use of units are consistent. Pdf calculation of the traction effort of switching locomotive. The higher the loco hp generally the higher the maximum db force. Calculating tractive effort page 1 locomotives and. Maximum rear wheel tractive force from drive torque, frwmax n maximum rear wheel force from drive torque, ffwmax n maximum rear wheel tractive force before slip, frwmumax n maximum front wheel tractive force before slip, ffwmumax n total tractive force generated by both rear wheels, ftr n. How to calculate traction torque on wheel of automobile. If the design has two drive wheels, the force applied per drive wheel for straight travel is half of the calculated tte. To do this we will use the maximum tractive effort calculated in equation 9 which was 100 lbs. The data points calculated in order to produce a torque diagram may also be used to ascertain the mean or average tractive force produced. Shear stress is also occasionally referred to as the tractive force. Tractive force steam locomotives calculator fx solver.
Road load and tractive force the road load consists of t t i w ro sf ad cr f f f f f 1 the rolling resistance force f ro is produced by the tire flattening at the roadway contact surface. Vehicle forces for driving up slope equations and calculator. The dynamic equation of vehicle motion along the longitudinal direction is expressed by where dvdt is the linear acceleration of the vehicle along the longitudinal. Traction can also refer to the maximum tractive force between a body and a surface, as limited by available friction. This force, which is simply the pull of water on the wetted area, is known as the tractive force chow, 1959 t.
This calculator can be used to calculate the maximum acceleration and minimum accelation time for a car on different surfaces. Rr force necessary to overcome rolling resistance lb. The wheel torque is the torque from the engine the drive ratios of geabox final dive ratio. As an approximation, the following formula can be used for a twocylinder locomotive t d 2 s p w. Equations behind the vehicle forces for driving up slope calculator. See equations dehind this calculator vehicle driving forces equations. The total tractive effort tte is the sum of the forces calculated in steps 1, 2, and 3. Keep in mind the db force produced is directly related to the number of axles a loco has. W weight or vertical force between wheel and surface n, lb f m mass on the wheel kg, slugs a g acceleration of. As with power there are different methods of measuring tractive effort. The third radius shown in figure 1 is called the torque radius rt. Tractive effort and acceleration ce 322 transportation engineering dr.
Cte is non applicable for an ac traction motor, which use te only. Adhesion is the grip or force of attachment, produced by. Chapter 8 threshold channel design 210vineh, august 2007 issued august 2007 the u. Calculating tractive effort for steam locomotives when modeling a set of train vehicles, an important information needed for the dynamics of a locomotive is max tractive effort te, resp max te, which is determining the ability of a locomotive to pull up a train. What we are going to do now is map out the turning force a sample engine will provide to the wheels throughout the gear, creating what is called a tractive effort graph, which as the name implies shows the amount of traction needed to put the power to the ground without wheel spin. If the rear wheels of the vehicle in the figure are driven with no slip taking place between the tires and the level road surface, the wheel force or the tractive effort te is equal to the torque at the driven wheels t w divided by the rolling radius or effective radius r w. What is difference between tractive force and tractive. The traction parameters involving forces are all normalized by dividing by wd, the dynamic force reaction supporting the wheel or traction device. This will be recognized as the sverage boundary shear. First, a force of 2 to 5 pounds per ton of train weight is required to move on straight level track.
The maximum permissible traction force that can be applied to the wheels is governed by two things. Drive wheel motor torque calculations ufl mae concrete good. Jun 20, 2018 tractive effort is the force available at the area of contact between the rear wheel tyres and the road for a rear wheel driven car. The tractive force ft in the contact area between the tires of the driven wheels. W weight or vertical force between wheel and surface n, lb f m mass on.
Maths help converting tractive effort to torque nm. Tractive effort is a measure of the force that a locomotive can apply to the train it is pulling. Static loaded radius is more appropriate to use for force or moment calculations. Total tractive effort is the net horizontal force applied by the drive wheels to the ground. Continuous tractive effort is the tractive force that can be maintained indefinitely, as distinct from the higher tractive effort that can be maintained for a limited period of time before the power transmission system overheats. Morphologic and hydraulic properties of sacramento river between chico landing site e10 and woodson bridge, california 57 iv. In future months design parameters for a diesel and steam locomotive. Tractive effort te is the force applied by a locomotive for moving itself and a train. To choose motors capable of producing enough torque to propel the example vehicle, it is necessary to determine the total tractive effort tte. Although hec15 is recommended for design flows less than 50 ft3sec 1. On higher speed vehicles friction in drive components may warrant the addition of 10%15% to the total tractive effort to ensure acceptable vehicle performance. Tractive effort is defined as the force at the rims or the outer edges of the driving wheels of moving trains. F tf is zero for a rearwheeldriven vehicle, whereas f tr is zero for a frontwheeldriven vehicle.
For tractional torque you have to calculate the traction force requirement by your vehicle. Pdf calculation of the traction effort of switching. Tractive force for hard, smooth surfaces is a proportional function of weight and the coefficient of friction of the two materials in contact. A power presizing methodology for electric vehicle. Torque diagrams such as figure 7 clearly illustrate the varying nature of the tractive force produced by a steam locomotive under the theoretical conditions described. Tractive force calculation for a vehicle tractive force or tractive effort or traction is the force applied between the tire and road surface to move a car or any vehicle for that matter.
Equation 1 describes vehicle longitudinal motion and. The backbone of train simulation physics is the simple equation, fma force mass x acceleration. Material provided by sachin buddhisagar, copyright 2011. Tractive effort is the force available at the area of contact between the rear wheel tyres and the road for a rear wheel driven car. Force of vehicles engine maximum value transferable maximum tractive effort define the point at which additional enginegenerated tractive effort is not productive. Shear stress is the force applied by flowing liquid to its boundary. As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion. If a cross over the tractive effort curve would appear for the next gear by remaining in gear until maximum rpm, then a small, roughly triangular shaped section would be cut out of the available area every time when gear is changed. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. So in this case its wheel torque the rolling radius from cenre of wheel to outer egde of tyre.
The document was revised to add background information, examples, and a glossary and to expand the bibliography. The changes in the design procedure are those that remove references to allowable velocity procedures and replace them with tractive stress evaluations. See equations dehind this calculator engineers edge. 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. Tractive force when water flows in a channel, a force is developed that acts in the direction of flow on the channel bed. Sep 11, 2017 without any context it is difficult to say how it isnt just a force. In the main line train, tractive effort is caused by the locomotive, and in a suburban train, it is caused by motor coaches. Put simply, shear stress describes the force of water that is trying to drag the channel surface downstream with it. Locomotive tractive effort and power calculations tractive effort calculations. Jan 07, 20 tractive force calculation for a vehicle tractive force or tractive effort or traction is the force applied between the tire and road surface to move a car or any vehicle for that matter. The tractive effort required to move a train consists of numerous factors, but for most applications only four need to be considered. Horsepower and tractive effort the idiots guide to. Power is the force needed to run a train at a certain speed. For slopes, you will need an additional 100 newton per percent of steepness.
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