It is the amount of force a wheel can apply to a surface before it slips. To the rolling resistance we must add the resistance due to grade and. At higher speeds, the tractive effort is limited by the power that can be delivered at the wheelrail contact. Traction motor used for traction purpose is dc series motor, separately excited dc series motor, three phase induction motor, synchronous motor and permanent magnet synchronous motor. The tractive force between a car wheel and the surface can be expressed as. Subsequent comments should be made in a new section. To do this we will use the maximum tractive effort calculated in equation 9 which was 100 lbs. Tractive effort is a result of available horsepower and weight on drivers just as a muscle car can have so much power that itll spin its tires easily, so too can a loco. At high speed over 30 mph we must also add air resistance, but since. Whatever may be source or principle of working of traction motor, all provide tractive effort characteristics to encounter train resistance and provide acceleration. The locomotive type 120 is an ac electric locomotive equipped with 3phase traction motors.
Tractive effort and tractive resistance c12 springerlink. The fuel to satisfy tractive effort adjusted by the application of supplemental power from a hybrid eergy n storage system fuel to charge the hybrid electric system 3. Dieselelectric traction has the following advantages. The acceleration force is a function of the mass of the vehicle. Tractive effort definition of tractive effort by merriam. Influence of vehicle speed on the form of creepforce functions. Continuous tractive effort is often shown in graph form at a range of speeds as. For example the canadian set has coal wagons that limit the trains speed to 128 however, you also need a van in the back of the train or the trains speed is halved. In other words, it is the sum of the tractive force and rolling effort on the road surface. A wheel will have different traction on different surfaces, as, the coefficient. When a train is on a slope, a force of gravity equal to the component of the dead weight along the slope acts on the train and tends to. Tractive effort is defined as the force at the rims or the outer edges of the driving wheels of moving trains.
I suggest the merge of continuous tractive effort and maximum tractive effort into this article. The values given in table 1 do not take into account the variation of fr with speed. Increasing this tractive effort increases the acceleration rate. To map out our tractive effort for 1st gear we simple take our torque and multiply it by the total gear ratio for 1st. Duty cycle characterization and evaluation towards heavy. 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. 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. Tractive effort for overcoming the effect of gravity. 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. Ive also suggested merging power at rail ie making power at rail redirect to a subsection of this article dealing with the relationship between power at rail, speed and tractive. Understanding torque and horsepower with tractive force. 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. Te is the tractive effort n r w is the rolling radius or effective radius m. If the rear wheels have such a torque applied to them that they are on the.
Better the torque, lesser the time required by the vehicle to reach a given speed. If the wheel cuts into the road surface, the tractive resistance is thereby increased. The term tractive effort is often qualified as starting tractive effort, continuous tractive effort and maximum tractive effort. So if they could handle the tractive effort of 80 000, then the engineer should not drive below 9. Speed ms 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. We now have the speed rpm and the required tractive effort. F traction effort or force acting on the wheel from the surface n, lb f. Pdf a common feature of all engines with internal combustion is the need for. Resistance bound to the slope of 2% will oppose a force of fp 220 tons x 9,806 knewton x 2 100 64,7 kn.
This quantity does not change with the number of drive. Drive wheel motor torque calculations university of florida. Tractive effort of steam locomotives locomotive ratiosii. The increase of differential speed corresponds with the decrease of tractive effort. The continuous tractive effort would be determined by how much electricity traction motors could handle before burning up. The final factor and one frequently overlooked is the tractive effort required for acceleration of the train. Hence tractive effort required for acceleration f a 277. Innovative method for measuring the tractive effort of.
The exact determination of the law of variation is of no great importance. Pdf tractive effort curves in gearbox analyse researchgate. Tractive effort is a measure of how well the power figure is applied to the track, acceleration i spose. The total tractive effort tte is the sum of the forces calculated in steps 1, 2, and 3. W weight or vertical force between wheel and surface n, lb f m mass on the wheel kg, slugs a g acceleration of. It takes about 10 pounds per ton to accelerate to a speed of 6 miles per hour in one minute or 12 miles per hour in two minutes, a reasonable rate for a heavy train. A huge amount of data, related not just to the gearbox, can be obtain when comparing results of these two methods and using them together.
The top speed is mainly determined by the value of c. Emd passenger and freight locomotive of 4500 hp commissioned by the. Low tractive effort will mean that even something with a high power figure will struggle to get up to speed. Bachmann locos class 20, 37 and 66 vitrains class 37 pulling force one couplers all data are in metric grams. Tractive effort is measured in pounds of force available as a function of speed. A heavy freight engine would want high power and high tractive effort. Even aside from adhesion limitations, the transmission can only produce so much te, and a locomotives actual capability at 1 mph, or 5 mph, or 10 mph isnt that well known by. In addition, many custom sets have speed limits for wagons and other frustrating surprises if you dont know about them. Pdf calculation of the traction effort of switching. Tractive effort and wheel slip control of locomotive type 120.
A, b and c are constants that change depending on the train. In the main line train, tractive effort is caused by the locomotive, and in a suburban train, it is caused by motor coaches. The last step is to calculate the axle torque required to generate this tractive effort. Total tractive effort required by both front wheels, ftf n total tractive effort of the machine, ftm n force from gravity acting along the incline, fg n. These terms apply to different operating conditions, but are related by common mechanical factors. The motor torque bears a direct relationship with the acceleration force. Tractive effort inversely varies with speed at any given level of available power. Train movement and energy consumption electrical engineering. The speed at which both forces are equal is the maximum speed the train can get to on a flat piece of track. Speed and resistance for conventional freight train. Vehicle forces for driving up slope equations and calculator. Tractive resistance wheel, axle, friction, varies, road. Tractive effort of steam locomotives locomotive ratiosii by a. Vehicle dynamics calculation tractive effort of a car.
After the detection of higher adhesion the differential speed is reduced to almost zero, which is a hint for dry tracks. The maximum permissible traction force that can be applied to the wheels is governed by two things. Tractive effort, acceleration and braking 1tractive effort. The necessary tractive effort f t 220000 mass in kg x 0,23148 acceleration 50926 newtons, or. 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. At a given power output a locomotives tractive effort is inversely proportional to its speed, and obviously that cant forever continue to be true as speed decreases.
Because of the group control the axle speeds related to one converter show almost no variation. This video explains how horsepower and tractive effort are related through speed. For this purpose, a wheel slip control is integrated into the tractive effort control system. Traction can be defined as the friction between a drive wheel and the surface it moves upon. For the transmission of the high tractive efforts an optimal use of the available adhesion is required. Tractive effort, curving and surface damage of rails. Please attach distancespeed curves for the three train conditions listed in the locomotive specification, sec. Pdf influence of locomotive tractive effort on the forces between. 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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