This can be calculated in either static condition i. Research shows that about 20% to 55% of the available tractor energy is wasted at the tractive devicesoil interface. Influence of locomotive tractive effort on the forces between wheel and rail article pdf available in vehicle system dynamics 35supplement. Calculate the ohe current at 25kv, assuming an efficiency of locomotive as 80% and off of 0. Steering effort is defined as the effort to be made by the driver in turning the steering wheel. The total tractive effort tte is the sum of the forces calculated in steps 1, 2, and 3.
The tractive effort of a locomotive should be enough for it to haul a train at the maximum permissible speed. What is the difference between torque and tractive effort. For steam locomotives, tractive effort was usually the limitting factor in the size of the train it could pull. Firstly, for those not used to formulae, the relationship between tractive effort and horsepower expressed in oltmannds posting could be expressed as. Tractive effort is defined as the force at the rims or the outer edges of the driving wheels of moving trains. Ive found this formula to calculate tractive effort from torque but as my algebra sucks i cant work out how to reverse it or how to calculate overall gear reduction my brain is melting. Pdf calculation of the traction effort of switching. 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. Pump and motor sizing guide heavy duty hydrostatic transmissions.
In vehicle performance calculation, it is sufficient to consider the rolling resistance coefficient. Calculating tractive effort on incline transport tycoon. Torque torque is a measure of how much a force acting on an object that causes the object to rotate about an axis. Tractive effort curve mathematics in education and industry. Horsepower and tractive effort the idiots guide to. To find the net drawbar pull, subtract the rolling resistance from the tractive effort. Material provided by sachin buddhisagar, copyright 2011. Force of vehicles engine maximum value transferable maximum tractive effort define the point at which additional enginegenerated tractive effort is not productive. The tractive force between a car wheel and the surface can be expressed as. Equations behind the vehicle forces for driving up slope calculator. Tractive effort, when multiplied with speed at which the train is required to run, gives the horsepower. The tractive force was measured by the disturbance observer in 8. 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. Available tractive effort road vehicle performance.
Pdf influence of locomotive tractive effort on the. 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. Ste is the amount of tractive effort that must be produced by the motive power to start moving a train from a dead stop without slipping the wheels. W weight or vertical force between wheel and surface n, lb f m mass on the wheel kg, slugs a g acceleration of. General aspects of railway traction what really causes the train to accelerate or br ake are the adhesion forces that appear in the wheelrail contact.
Im sure its more complex than that but if anyone could shed. Vehicle dynamics calculation tractive effort of a car. This torque must be generated in a motor or braking system that. 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. Maximum tractive or braking effort is obtained if each powered wheel of the. But it doesnt provide realistic values, so i am wondering, what is the correct way of calculating tractive effort. For a given tractive effort, increased horsepower allows an increased speed with other things remaining the same. Construction planning, equipment, sixth edition chapter. Im guessing that there is factor for adhesion x horsepower x weight x axles. Tractive effort determines how much a locomotive can haul. The speed at which both forces are equal is the maximum speed the train can get to on a flat piece of track. Hi there again, i am trying to correctly calculate the tractive effort pf a train, currently i do this.
Acceleration is a measure of how quickly you are gaining or losing speed. When maximum vehicle tractive effort and maximum vehicle speed in the normal working range are specified. Tire traction can also refer to the maximum tractive force between a body and a surface, as limited by available friction. Note that horsepower isnt part of the calculation for tractive effort. Vehicle forces for driving up slope equations and calculator. Tractive force at each rear wheel gate 1992 fmp2 youtube. Section 2 describes the various types of motor used for gauge o locomo. Measurement of tractive force in the creep region and. Car vehicle driving up a slope equation and calculator. 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. 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. Tractive effort te and tractive resistance tr tractive effort te. The tractive coefficient is calculated by the division of the estimated tractive force and the axle weight based on the definition in 3. Permanent and parttime four wheel drive and typical.
Maximum tractive effort is defined as the highest tractive force that can be generated under any condition that is not injurious to the vehicle or machine. Tractive effort and acceleration ce 322 transportation engineering dr. Te effective machine weight x adhesion coefficient. Tractive force steam locomotives calculator fx solver. Otherwise it is the force required to turn or twist an object.
For simulations and calculations a quadratic formula is used to represent resistance to motion. In most cases, maximum tractive effort is developed at low speed and may be the same as the starting tractive effort. Posted by doublestack on thursday, september, 2007 8. Tractive effort or tractive force is measured in kilonewtons kn or pounds force lbf where 1 kn 228. The maximum permissible traction force that can be applied to the wheels is governed by two things. Tractive effort te is the force applied by a locomotive for moving itself and a train. An ordinary steam locomotive relies upon rotational force or torque developed at the driving wheels produced by the. To do this we will use the maximum tractive effort calculated in equation 9 which was 100 lbs.
Using equation 1 we calculate the tractive force at wheels for different gears. Again, complete the calculations, and youll discover that the tractive effort or gross pulling force of the vehicle is 2,667 pounds. The total axle torque is tractive effort times the. First, a force of 2 to 5 pounds per ton of train weight is required to move on straight level track. For a railway to operate efficiently and safely, its locomotives should be powerful enough to accelerate their trains rapidly to the maximum allowed line speed, and the braking systems must be able to bring a train reliably to a standstill at a station or signal, even on an adverse gradient. Or tractive force is nothing but the net force present at wheels. Total tractive effort required by both front wheels, ftf n. An estimate for the tractive effort of a single cylinder steam locomotive can be obtained from the cylinder pressure, cylinder bore, stroke of. Calculating tractive effort on incline post by kboogle. Tire traction force, or tractive force, is the force used to generate motion between a car or truck and the road or tangential surface. Importance of tractive effort lies with its capability to start a train on the gradient and run it up to a speed of around 30 kmph whereas that of horse power is its ability to achieve and run at the maximum permissible speed. In railway engineering, the term tractive effort is often used synonymously with tractive force to describe the pulling or pushing capability of a locomotive. F traction effort or force acting on the wheel from the surface n, lb f. Maths help converting tractive effort to torque nm discussion in science started by ikonz0r, mar 27, 2014.
An amount of torque distributed to the wheel from differential divided by wheel radius is the tractive effort an. 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. Maths help converting tractive effort to torque nm. A 2000t train is running at a speed of 100kmph with a tractive effort of 12t.
As with power, there are different methods of measuring tractive effort. The tractive effort required to move a train consists of numerous factors, but for most applications only four need to be considered. In other words, it is the sum of the tractive force and rolling effort on the road surface. The maximum traction effort co uld be calculated by 9 and 10 with respect to changing of the frictions forces with different atmosphere conditions dr y and wet surfaces.
The tractive effort of a locomotive is the force that the locomotive can generate for hauling the load. For these adhesion forces to appear, tractive or braking effort needs to be applied to the wheels. In this case, the drawbar pull of our example vehicle is 2,547 pounds. The last step is to calculate the axle torque required to generate this tractive effort. 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. To choose motors capable of producing enough torque to propel the example vehicle, it is necessary to determine the total tractive effort tte. Tractive effort and tractive resistance c12 springerlink. Tractive effort is a measure of the force that a locomotive can apply to the train it is pulling.
Tire traction force equation and calculator engineers. This energy wears the tires and compacts the soil to a degree that may cause detrimental crop production burt et al. The backbone of train simulation physics is the simple equation, fma force mass x acceleration. Train resistance and tractive effort are both measurements of force typically in pounds in north america so we can simply overlay the curves how do we relate tractive effort curves to train resistance. Locomotive tractive effort and power calculations tractive effort calculations. In the main line train, tractive effort is caused by the locomotive, and in a suburban train, it is caused by motor coaches. What is difference between tractive force and tractive effort. We now have the speed rpm and the required tractive effort. What is the maximum speed possible for this train with this locomotive.
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