We now have the speed rpm and the required tractive effort. Power is the force needed to run a train at a certain speed. What is the maximum speed possible for this train with this locomotive. But as i said, when you measure both at the same point, horsepower is speed times tractive effort divided by 375, with no qualifications. Tractive effort definition of tractive effort by merriam. Tractive effort te and tractive resistance tr the car tech. 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. Tractive effort te is the force applied by a locomotive for moving itself and a train. Ab this is constant tractive effort line generally up to a speed of 3050kmph. 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 force between a car wheel and the surface can be expressed as. As with power, there are different methods of measuring tractive effort. Tractive effort determines how much a locomotive can haul.
May 11, 2007 rolling resistance 140n per kg frontal area 2msquared drag coefficient 0. Research shows that about 20% to 55% of the available tractor energy is wasted at the tractive devicesoil interface. The tractive effort of a locomotive should be enough for it to haul a train at the maximum permissible speed. Horsepower and tractive effort the idiots guide to. Due to the relationship between power p, velocity v and force f, described as. If the rear wheels have such a torque applied to them that they are on the. The backbone of train simulation physics is the simple equation, fma force mass x acceleration. Tractive effort is the propelling force which a locomotive exerts at the rims of its driving wheels. Firstly, for those not used to formulae, the relationship between tractive effort and horsepower expressed in oltmannds posting could be expressed as. Is the maximum tractive effort of a vehicle dependent on rolling resistance or the road adhesion. Jun 22, 2017 tractive effort te is the force applied by a locomotive for moving itself and a train.
Tire mechanics equates it to coulombs friction force which is dependent on road adhesion. Tractive effort versus horsepower trains magazine trains. Tractive effort is defined as the force at the rims or the outer edges of the driving wheels of moving trains. Introduction to highway transportation engineering, module 02. 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. 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. Im assuming power is how quickly the train will accelerate and tractive effort is ability to climb hills, but im not sure. I will wait a bit for clarification before making any alterations. In other words, it is the sum of the tractive force and rolling effort on the road surface.
Tractive effort force available to perform work resistance force impeding vehicle motion tractive effort and resistance major sources of vehicle resistance. As with power there are different methods of measuring tractive effort. For slopes, you will need an additional 100 newton per percent of steepness. In the last chapter we discussed the equation for approximating tractive effort. In automotive engineering, the terms are distinctive. Tractive effort and train resistance horsepower friction scribd. Te effective machine weight x adhesion coefficient. Tractive effort te and tractive resistance tr tractive effort te. In the main line train, tractive effort is caused by the locomotive, and in a suburban train, it is caused by motor coaches. Maximum tractive or braking effort is obtained if each powered wheel of the. The tractive effort required to move a train consists of numerous factors, but for most applications only four need to be considered. The resistance to motion due to friction per unit weight hauled.
Tractive effort curve mathematics in education and industry. 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. Is the maximum tractive effort of a vehicle dependent on. When tractive effort te is equal to the tractive resistance tr a vehicle would be either stationary or moving at a uniform velocity. Tractive force steam locomotives calculator fx solver. The tractive gps tracker is generally as accurate as any standard gps global positioning system technology. These equations do not prove to be accurate in reality as the resistance to. Tractive resistance wheel, axle, friction, varies, road. Preceding unsigned comment added by fengrail talk contribs 02. May 12, 20 whatever may be source or principle of working of traction motor, all provide tractive effort characteristics to encounter train resistance and provide acceleration. Nov 10, 2016 what is the difference in tractive effort and power in the locomotive stats.
Tractive effort and train resistance free download as pdf file. Sps performance standard, gps signals provide an accuracy of 7. Caculating tractive force i need a formula physics forums. Morin concluded that the resistance varies inversely as the first power of the diameter of the wheel. Tractive effort or tractive force is measured in kilonewtons kn or pounds force lbf where 1 kn 228. Tractive effort is the force needed to simply move the train. The tractive effort of a locomotive is the force that the locomotive can generate for hauling the load. For passenger cars, the height of the center of application of aerodynamic resistance, h. W weight or vertical force between wheel and surface n, lb f m mass on. 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. Vehicle dynamics cee 320 steve muench outline resistance aerodynamic rolling grade tractive effort acceleration braking force stopping sight distance ssd main concepts resistance tractive effort vehicle acceleration braking stopping distance resistance resistance is defined as the force impeding vehicle motion what is this force. Locomotive tractive effort and power calculations tractive effort calculations. Traction can be defined as the friction between a drive wheel and the surface it moves upon.
Intersection of tevsspeed curve, with train resistance curve. The maximum permissible traction force that can be applied to the wheels is governed by two things. 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. Tractive effort and tractive resistance c12 springerlink. While this equation does an excellent job, there are other quirks that the locomotive traction motors have that it doesnt take into account. Vehicle dynamics calculation tractive effort of a car. To do this we will use the maximum tractive effort calculated in equation 9 which was 100 lbs. First, a force of 2 to 5 pounds per ton of train weight is required to move on straight level track. This energy wears the tires and compacts the soil to a degree that may cause detrimental crop production burt et al. Note that horsepower isnt part of the calculation for tractive effort. It is usually expressed in pounds the relation between tractive effort, rail horsepower, and speed in miles per hour is tractive effort 270 rail horsepower kg speed note. For a given tractive effort, increased horsepower allows an increased speed with other things remaining the same.
Acceleration is a measure of how quickly you are gaining or losing speed. 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 tw divided by the rolling radius or effective radius rw. Oct 06, 2016 if you measure tractive effort at the wheel rim, and horsepower somewhere else, then you have to estimate the losses between those two locations. Tte total tractive effort lb rr force necessary to overcome rolling resistance lb gr force required to climb a grade lb f a force required to accelerate to final velocity lb the components of this equation will be determined in the following steps. The rolling resistance of a train on straight level track is approximately. 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. F traction effort or force acting on the wheel from the surface n, lb f. Tractive effort definition is the force in pounds exerted by powered equipment as a locomotive as measured for statistical purposes at the rim of the driving wheels.
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