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I think some guys dont understand the laws of physics at work here.More tractive effort dosen,t mean more power.More TE allows more power to be applied.It works that way for all vehicles.Take for instance your car on a gravel road.It is easy to spin your tires on loose gravel from a start. But as your speed increases it becomes harder to spin your tires.Once you get going say maybe 20 mph or so you cant spin your tires even with the pedal to the floor.The friction between the gravel and your tires is the same at 20 mph as it is at 2 mph.The difference is speed.The faster a object travels,the less friction that is required to apply a given amount of power.So to put it in a nutshell below 20-25 mph most road locomotives are not able to use all of their horsepower.If they did their wheels would spin like crazy.Trains Mag did an article on this a few years ago.They had a graph which showed that an SD40 has to travel almost 25 mph before it can use all of its horespower.Sure some models may have better wheel slip control and better weight distribution but you can,t ignore gravity and friction.I am sure we have all seen GP40's and SD40's moving at 10 or 12 mph in notch 8 but believe me they weren't using all their HP.Thats because the amount of power going through to the traction motors is regulated on all locomotives.As speed increases more power is allowed to be applied.With high speed trains HP becomes more important because at 70 mph adhesion isn't a problem.What you need is brute HP to move tonnage fast.But on mine runs and drag frieghts TE is more important.I was looking at an old Rio Grande timetable and on the 3% grade up Tennessee Pass. When placing helpers on the rear of a train just ahead of the caboose it states that no more than 18 powered axles are to shove the train.The timetable dosen't care if its F units or SD45's.As long as the weight per axle is somewhat consistent,each axle will pull or pu***he train with the same amount of force,at slow speeds regargless of the type of unit.Limiting the number of axles keeps from shoving the train off the track.I have always been interested in how RR's use power and adhesion and I have found in my travels that very few railfans understand it. <br />Ron
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