02-12-2009, 08:28 PM
Thanks, Shane. 
I'm sure that there are some steam locos available that will pull a decent train, but a lot of model steamers do seem to be out-of-balance and/or too light. Some of their pulling ability is lost in the side rod and valve motion, too, and the larger diameter wheels, just like the prototype, are prone to slip more easily. Another thing to keep in mind is that I'm doing this to make the locos suitable for use on my layout, which has a lot of curves and a lot of grades, most occurring at the same place. I also like to run some heavy trains. For instance, Mister Nutbar's 2-10-2 would be an excellent loco for my layout if it would fit on my turntable, but I doubt that its tractive effort will ever be put to the test on his own layout: I don't doubt that it could pull a hundred normal-weight cars on straight, level track.
I have a Proto USRA 0-8-0 switcher that couldn't move four regular boxcars up the grade to my station at Dunnville. It's a beautiful-running locomotive, but no "oomph". I was going to get rid of it, but, fortunately, took it apart to see what the problem was. I discovered that the cast weight (of a similar light material as that of the Athearn Mikado) had been cast to accommodate a circuit board for the headlight and a tiny flywheel, the mass of which didn't appear adequate to have any effect. By replacing those unnecessary, to me, at least, items with lead, then adding more where space was available, I was able to double its tonnage rating to eight cars - good enough to make it onto the roster and merit a complete makeover, too.
![[Image: CNR%208414........jpg]](https://i23.photobucket.com/albums/b399/doctorwayne/locos%20switching%20industries/CNR%208414........jpg)
A good test when you're adding weight to any loco is to apply power to it while physically restraining it from moving - for a steam loco, simple hold the tender, while a car coupled to a diesel will serve the same purpose. If the wheels slip, the loco is not too heavy for its motor. If the wheels don't slip, the motor will continue to try to turn, with the result that it will begin to overheat. If it gets hot enough, the insulating varnish on the motor windings will melt, damaging or destroying the motor. Many locos can handle much more weight than would be possible to hide within them, though.
Unless there's a flaw within the drivetrain (such as split gears) the added weight is unlikely to cause added strain to either the motor or other mechanical parts. Excessive wheelslip can, however, wear away the plating that's found on most loco drive wheels, so, while it's good that the wheels are able to slip when the load is too great, it's best not to tax your locos to that point.
I think that for most modellers, though, the pulling ability of a loco is not high on their list of requirements. So, if it runs well and has the details and other features that they want, it's probably "good enough" as it is, right out of the box.
This, of course, makes my thread here something of limited interest for most. For me, though, it's an integral part of the way I do model railroading. :mrgreen:
Wayne
I'm sure that there are some steam locos available that will pull a decent train, but a lot of model steamers do seem to be out-of-balance and/or too light. Some of their pulling ability is lost in the side rod and valve motion, too, and the larger diameter wheels, just like the prototype, are prone to slip more easily. Another thing to keep in mind is that I'm doing this to make the locos suitable for use on my layout, which has a lot of curves and a lot of grades, most occurring at the same place. I also like to run some heavy trains. For instance, Mister Nutbar's 2-10-2 would be an excellent loco for my layout if it would fit on my turntable, but I doubt that its tractive effort will ever be put to the test on his own layout: I don't doubt that it could pull a hundred normal-weight cars on straight, level track.I have a Proto USRA 0-8-0 switcher that couldn't move four regular boxcars up the grade to my station at Dunnville. It's a beautiful-running locomotive, but no "oomph". I was going to get rid of it, but, fortunately, took it apart to see what the problem was. I discovered that the cast weight (of a similar light material as that of the Athearn Mikado) had been cast to accommodate a circuit board for the headlight and a tiny flywheel, the mass of which didn't appear adequate to have any effect. By replacing those unnecessary, to me, at least, items with lead, then adding more where space was available, I was able to double its tonnage rating to eight cars - good enough to make it onto the roster and merit a complete makeover, too.
A good test when you're adding weight to any loco is to apply power to it while physically restraining it from moving - for a steam loco, simple hold the tender, while a car coupled to a diesel will serve the same purpose. If the wheels slip, the loco is not too heavy for its motor. If the wheels don't slip, the motor will continue to try to turn, with the result that it will begin to overheat. If it gets hot enough, the insulating varnish on the motor windings will melt, damaging or destroying the motor. Many locos can handle much more weight than would be possible to hide within them, though.
Unless there's a flaw within the drivetrain (such as split gears) the added weight is unlikely to cause added strain to either the motor or other mechanical parts. Excessive wheelslip can, however, wear away the plating that's found on most loco drive wheels, so, while it's good that the wheels are able to slip when the load is too great, it's best not to tax your locos to that point.
I think that for most modellers, though, the pulling ability of a loco is not high on their list of requirements. So, if it runs well and has the details and other features that they want, it's probably "good enough" as it is, right out of the box.
This, of course, makes my thread here something of limited interest for most. For me, though, it's an integral part of the way I do model railroading.
:mrgreen: Wayne