01-03-2009, 01:46 PM
INCOMPATIBILITY BETWEEN ROLLING STOCK AND RADIUS
I'll start this off with the results of some experiments that I did on my first layout. In fact the description of the experiment and the results might make further discussion of this point unnecessary.
On my first layout, I used flex track, but I made 22 inches my minimum radius for the mainline. I had some sidings that were 18 inch radius, and then I had a couple of industries that were a tight fit (didn't want to waste any real estate) so I installed some 15 inch radius snap track.
This layout was built in the early 1980's, and I was using Sd45's & Sd40-2's for mainline power. I had Gp7's for local switchers, and Sw7s for the yard. The plan from the very beginning was that the Gp7's or the Sw7's would always switch those industries with 15 inch radius curves leading into them, never an Sd45.
Strictly as an experiment, I tried running my Athearn Sd45 through the 15 inch radius curves, and it worked fine although it looked ugly doing it. Then I tried coupling a 40 foot boxcar to the Sd45 and running it through the 15" curve. The 15" curve went to the right out of a #4 turnout. The Sd45 was able to push the boxcar through the turnout and into the 15" curve without any problems until the locomotive started into the 15 " curve. As soon as the Sd45 went into the 15" curve the boxcar tipped up on its side. The left side wheels stayed on the track, but the right side wheels raised up about 1/4 inch off the rails. Once the locomotive came out of the curve, the boxcar dropped back onto the rails. When I pulled the Sd45 back out of the siding with the boxcar in tow, the same "up on 2 wheels back down on all 4" happened again. The final experiment was to couple a Gp7 to the Sd45 and then couple the boxcar to the Gp7. when I did it that way everything worked fine.
I learned about dynamics of locomotive length and coupler restrictions vs radius from that experiment.
If you have a curve that a particular freight car tends to derail in every time when it is coupled behind a particular engine, try a different car. If it does it consistently, it may be that the curve is too tight for that particular locomotive. Also the dynamics will change with freight car length. You may find the a 40 foot car will follow that big locomotive through the tight curve fine, but a 50 foot car or a 60 foot car has problems.
This is something that Fred Wright has posted on a number of threads dealing with minimum radius and rolling stock. If I'm remembering correctly, Fred has suggested that your minimum radius should be 3-3 1/2 times the length of the longest locomotive or car that you want to run. As an example an 85 foot passenger car in ho will be almost 1 foot long. The traditional recommendation for 85 foot passenger cars is a 30in minimum radius, but using Fred's formula, 36-40 inches would be a better choice. As model railroaders we seem to have a constant battle going on between the amount of room I want for the radius I want versus the amount of space I have. I will discuss talgo mounting vs body mounting of couplers in the next post, but one trick the manufacturers use to help long passenger equipment negotiate tighter radius curve is to mount the couplers to the trucks rather than body mount them. The body mounted couplers will always track toward the outside of a curve, the distance to the outside depending on the overhang of the particular piece of rolling stock. Talgo mounted coupler (coupler mounted to the truck) will always track to the center line of the curve. As a result, cars with talgo trucks will negotiate tighter radius curves when being pulled than cars with body mounts. Talgo's don't push worth beans! As soon as you try to push one the coupler wants to shove the truck off the track to the outside of the curve. If you want to run a passenger train, but don't have the room for the radius needed for full length cars you have 2 choices. You can run "shorty" passenger cars, or you may try cars with talgo trucks. You just can't back a talgo equipped passenger train very well at all. Also, if you locomotive has body mounted couplers, you may need to modify it to allow more swing on the locomotive couplers to allow it to track without pulling the cars off the track. The other thing you can do is make a "transition car" out of a baggage car or express box car or reefer which are typically shorter than the 85 foot full length passenger cars. Body mount the coupler that hooks to the engine and talgo mount the coupler that pulls the rest of the train.
--------------------------------------------------------------------------------
ROLLING STOCK PROBLEMS
If you have one locomotive or freight car that derails consistently at one spot on the railroad, but everything else you operate works fine at that spot, is it a track problem or a rolling stock problem?
If the problem piece of rolling stock is a unique piece that is longer than anything else, has longer wheelbase trucks than anything else, etc., you may have a track radius problem or a defect in the trackwork causing the derailments. If the problem piece is one of 2 or 3 or more identical pieces, and only one has the problem, you probably have an issue with that one piece of rolling stock.
Sometimes a particular car will work ok if it is just turned around in the train. That is fine if you want to watch you train run over the layout, but it is not acceptable if you want to do prototype operation. To do prototype operation, your rolling stock has to function correctly without derailing in either direction whether being pushed or pulled through any point on the railroad. In this section I will focus on tuning up rolling stock for it;s most efficeint operation.
The first thing I will mention is that most toy train sets come with what are called "talgo" trucks. That just means that the couplers are mounted to the trucks instead of to the body. That type of coupler mounting is used to allow the train to negotiate tight radius curves. It may work with Lionel & LGB large scale trains due to the very heavy weight of those models. I don't have any first hand experience with either one of those trains, so I can't speak about them. With ho and n scale trains, the dynamics of pushing on a car with talgo trucks is that the coupler will have a side force exerted on it that will try to push the coupler to the outside of the curve. With the relatively light weight of the individual car combined with a relatively heavy weight of the train it is pushing against, talgo trucks will always tend to derail to the outside of the curve you are pushing them through, and sooner or later they will derail 100% of the time they are being pushed. The problem is compounded because all of the best "model railroad locomotives" will have body mounted couplers, and most r-t-r or kit built model railroad rolling stock also will have body mounted couplers. When rolling stock with body mounted couplers goes through a curve, the coupler will swing over toward the outside rail. The talgo coupler will track through the center of the rails. Basically we have an incompatability problem, and that incompatability must be addressed before we go farther. The trainset locomotive will also have talgo trucks, but because the trainset locomotive is light in weight, usually with a poor quality, poorly designed drive system, they are not very good pullers anyway. Fortunately the fix is easy. The couplers will snap out of the trucks easily. You will also want to replace the plastic wheel sets with metal wheels for better operation so we can fix it all at once. Remove the coupler and wheels from the toy train trucks. Cut off the mounting tab that holds the coupler, and body mount the coupler. That brings me to my first tool recommendations.
<!-- m --><a class="postlink" href="http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=82838">http://www.ares-server.com/Ares/Ares.as ... t&ID=82838</a><!-- m -->
<!-- m --><a class="postlink" href="http://www.kadee.com/htmbord/page120.htm">http://www.kadee.com/htmbord/page120.htm</a><!-- m -->
The first tool in combination with a metal wheel set will make your cars free rolling.
To body mount couplers, most cars today come with some sort of knuckle coupler similar to the Kadee #5. Most of the new couplers will fit a Kadee coupler box, or you can just mount a Kadee #5 coupler (or Sergents or whatever your preference). Choosing your couplers is beyond the scope of what I want to address here. Take a suitable coupler box to mount to your rolling stock, and assemble the coupler/coupler box. Drill a #45 hole in the bottom center of your freight car's end. Tap the hole for a #2-56 screw, and fasten the coupler box to the underside of the car with a suitable length 2-56 screw. that brings us to the second tool on the list, the Kadee coupler height gauge. The Kadee gauge will fit over a section of track, put you car on the tracks and roll it over to couple with the coupler on the Kadee height gauge. When it is right, the coupler knuckles will line up perfectly, and the trip pin will just slide over the top of the little ledge at the bottom of the gauge between the rails.
Now we will presume that all of your rolling stock is compatible in terms of coupler heights and all of it has body mounted couplers. but this one car still derails at one point on the layout. We need to give the car a complete tune up.
The first thing I do is set the car on a piece of track on a perfectly flat level surface. With this test we are checking to see if the car's frame is warped in any way. What you are looking for is for all of the wheels on both sides of the car to sit properly on the rails. You might also want to check the car sitting directly on your flat surface to see if all flanges sit on the surface with no space between any flange and the surface. Athearn 4 bay open hoppers are famous for having warped frames, by the way. If a frame is warped, we can sometimes put it on a flat surface and put weight on the frame like a heavy book and leave it sit overnight to see if it will straighten out. This can only be done with a disassembled kit.
The second test I do with the car still sitting on the track is to check for the frame or body being bent, is the side of the car parrallel with the track?
Are the side frames of both trucks parrallel with the track?
Is there any tendency for either truck to appear to "crab walk" along the track due to one or more axles not being in perfect 90 degree alignment in relation to the truck side frames.
Now roll the car along the track section, is there any sign of a wheel not being centered on the axle indicated by one or more corners of the car going up and down as the car rolls?
Does the car or any of the wheels show signs of wobbling when it rolls on the test track? I have a Bachmann Plus F-7 unit that has one wheel on one axle that is not straight. When that locomotive runs down the track, it wobbles. If you find a wheel that either isn't concentric or wobbles, the only fix is to replace that axle & wheel set.
Now we need the next tool.
<!-- m --><a class="postlink" href="https://www.nmrastores.com/cgi/NMRA_...TION=NEXT+PAGE">https://www.nmrastores.com/cgi/NMRA_...TION=NEXT+PAGE</a><!-- m -->
This is The NMRA gauge. It is one of the most valuable tools you can have in your modeling box for model railroading. It is almost a universal measuring tool for model railroads.
We are going to use it to check the wheel gauge on our car. We need to check each axle individually. If you look closely around the outside of the gauge, you will see some small slots cut in the gauge that are marked for testing wheels for gauge. If both wheels on one axle won't fit into the grooves because the inside of one wheel interferes, the gauge is too tight. If it doesn't fit because one wheel is too wide for the gauge, the wheel set is too wide. Often times the wheels are an interference fit on the axle and by removing the wheels from the truck and twisting them in opposite directions while either pushing in or pulling out, you can adjust the gauge of the wheels.
The next test requires our next link.
<!-- m --><a class="postlink" href="http://www.nmra.org/standards/rp-20_1.html">http://www.nmra.org/standards/rp-20_1.html</a><!-- m -->
This link is to the NMRA recomended standards for weight of cars. find your scale on the chart and the length of the car and you can see what it should weigh. You can get inexpensive postal scales, or an inexpensive scale designed for weighing food portions on a diet. Both will work for what we are trying to do. If your car is too light, add weight to bring it up to the NMRA standard. On closed cars it is easy, you can glue pennies inside to bring up the weight. On open cars it is more of a challenge. You might use a load to add weight. I've used small lead shot gleued in voids in the frame with epoxy to add weight. You might change to metal trucks like a set of Kadee freight trucks to add some weight. You can even take a car apart and replace a steel or zamac weight between the car body and frame with sheet lead to add weight.
LEAD IS DANGEROUS MATERIAL THAT CAN PRODUCE LEAD POISONING IF NOT HANDLED PROPERLY. DO NOT LET YOUR CHILDREN HANDLE LEAD. DO NOT EVER SMOKE OR EAT WHILE HANDLING LEAD. DO NOT PUT YOUR HANDS INTO YOUR MOUTH OR RUB YOUR EYES WHILE HANDLING LEAD. WHEN YOU ARE FINISHED HANDLING THE LEAD, WASH YOUR HANDS THOROUGHLY WITH SOAP AND WATER.
There is one final test that need to be done on our car before we can declare that it is "tuned up."
Turn the car upside down and check the trucks for proper torque or tightness. We want a three point mounting for our trucks suspension system. To get that we want one truck just tight enough that it swivels freely, but doesn't rock. The other truck we tighten the same, then back off just enough to allow the car to rock side to side slightly.
We are done. If you have carefully followed every step in checking out you problem car, and done any corrective repairs needed, you should be rewarded with reliable operation.
Jim Thompson mentioned one other cause of rolling stock problems that I forgot. His post is in the thread a few posts down from this, but I'm going to rewrite it here in order that these first posts at the top of this thread might truly be comprehensive. I brought this post over from the other site, but I left the replies over there, so Jim's original post is still at the other forum.
You may have a car that derails, and when you check it out, everything seems to be in gauge and in spec. as far as weight, truck tightness, etc. The other thing to check is for interference between the truck and the frame, undercarriage, or details. This is especially important with cars with highly a detailed undercarriage, or one which you may have superdetailed the under carriage of a standard kit. The radius that the prototype uses is much bigger than anything we run. It is very easy when super detailing the undercarriage of a car with brake rigging, etc. to have a part that interferes with your truck swivel when negotiating the tightest radius curves on your layout.
I'll start this off with the results of some experiments that I did on my first layout. In fact the description of the experiment and the results might make further discussion of this point unnecessary.
On my first layout, I used flex track, but I made 22 inches my minimum radius for the mainline. I had some sidings that were 18 inch radius, and then I had a couple of industries that were a tight fit (didn't want to waste any real estate) so I installed some 15 inch radius snap track.
This layout was built in the early 1980's, and I was using Sd45's & Sd40-2's for mainline power. I had Gp7's for local switchers, and Sw7s for the yard. The plan from the very beginning was that the Gp7's or the Sw7's would always switch those industries with 15 inch radius curves leading into them, never an Sd45.
Strictly as an experiment, I tried running my Athearn Sd45 through the 15 inch radius curves, and it worked fine although it looked ugly doing it. Then I tried coupling a 40 foot boxcar to the Sd45 and running it through the 15" curve. The 15" curve went to the right out of a #4 turnout. The Sd45 was able to push the boxcar through the turnout and into the 15" curve without any problems until the locomotive started into the 15 " curve. As soon as the Sd45 went into the 15" curve the boxcar tipped up on its side. The left side wheels stayed on the track, but the right side wheels raised up about 1/4 inch off the rails. Once the locomotive came out of the curve, the boxcar dropped back onto the rails. When I pulled the Sd45 back out of the siding with the boxcar in tow, the same "up on 2 wheels back down on all 4" happened again. The final experiment was to couple a Gp7 to the Sd45 and then couple the boxcar to the Gp7. when I did it that way everything worked fine.
I learned about dynamics of locomotive length and coupler restrictions vs radius from that experiment.
If you have a curve that a particular freight car tends to derail in every time when it is coupled behind a particular engine, try a different car. If it does it consistently, it may be that the curve is too tight for that particular locomotive. Also the dynamics will change with freight car length. You may find the a 40 foot car will follow that big locomotive through the tight curve fine, but a 50 foot car or a 60 foot car has problems.
This is something that Fred Wright has posted on a number of threads dealing with minimum radius and rolling stock. If I'm remembering correctly, Fred has suggested that your minimum radius should be 3-3 1/2 times the length of the longest locomotive or car that you want to run. As an example an 85 foot passenger car in ho will be almost 1 foot long. The traditional recommendation for 85 foot passenger cars is a 30in minimum radius, but using Fred's formula, 36-40 inches would be a better choice. As model railroaders we seem to have a constant battle going on between the amount of room I want for the radius I want versus the amount of space I have. I will discuss talgo mounting vs body mounting of couplers in the next post, but one trick the manufacturers use to help long passenger equipment negotiate tighter radius curve is to mount the couplers to the trucks rather than body mount them. The body mounted couplers will always track toward the outside of a curve, the distance to the outside depending on the overhang of the particular piece of rolling stock. Talgo mounted coupler (coupler mounted to the truck) will always track to the center line of the curve. As a result, cars with talgo trucks will negotiate tighter radius curves when being pulled than cars with body mounts. Talgo's don't push worth beans! As soon as you try to push one the coupler wants to shove the truck off the track to the outside of the curve. If you want to run a passenger train, but don't have the room for the radius needed for full length cars you have 2 choices. You can run "shorty" passenger cars, or you may try cars with talgo trucks. You just can't back a talgo equipped passenger train very well at all. Also, if you locomotive has body mounted couplers, you may need to modify it to allow more swing on the locomotive couplers to allow it to track without pulling the cars off the track. The other thing you can do is make a "transition car" out of a baggage car or express box car or reefer which are typically shorter than the 85 foot full length passenger cars. Body mount the coupler that hooks to the engine and talgo mount the coupler that pulls the rest of the train.
--------------------------------------------------------------------------------
ROLLING STOCK PROBLEMS
If you have one locomotive or freight car that derails consistently at one spot on the railroad, but everything else you operate works fine at that spot, is it a track problem or a rolling stock problem?
If the problem piece of rolling stock is a unique piece that is longer than anything else, has longer wheelbase trucks than anything else, etc., you may have a track radius problem or a defect in the trackwork causing the derailments. If the problem piece is one of 2 or 3 or more identical pieces, and only one has the problem, you probably have an issue with that one piece of rolling stock.
Sometimes a particular car will work ok if it is just turned around in the train. That is fine if you want to watch you train run over the layout, but it is not acceptable if you want to do prototype operation. To do prototype operation, your rolling stock has to function correctly without derailing in either direction whether being pushed or pulled through any point on the railroad. In this section I will focus on tuning up rolling stock for it;s most efficeint operation.
The first thing I will mention is that most toy train sets come with what are called "talgo" trucks. That just means that the couplers are mounted to the trucks instead of to the body. That type of coupler mounting is used to allow the train to negotiate tight radius curves. It may work with Lionel & LGB large scale trains due to the very heavy weight of those models. I don't have any first hand experience with either one of those trains, so I can't speak about them. With ho and n scale trains, the dynamics of pushing on a car with talgo trucks is that the coupler will have a side force exerted on it that will try to push the coupler to the outside of the curve. With the relatively light weight of the individual car combined with a relatively heavy weight of the train it is pushing against, talgo trucks will always tend to derail to the outside of the curve you are pushing them through, and sooner or later they will derail 100% of the time they are being pushed. The problem is compounded because all of the best "model railroad locomotives" will have body mounted couplers, and most r-t-r or kit built model railroad rolling stock also will have body mounted couplers. When rolling stock with body mounted couplers goes through a curve, the coupler will swing over toward the outside rail. The talgo coupler will track through the center of the rails. Basically we have an incompatability problem, and that incompatability must be addressed before we go farther. The trainset locomotive will also have talgo trucks, but because the trainset locomotive is light in weight, usually with a poor quality, poorly designed drive system, they are not very good pullers anyway. Fortunately the fix is easy. The couplers will snap out of the trucks easily. You will also want to replace the plastic wheel sets with metal wheels for better operation so we can fix it all at once. Remove the coupler and wheels from the toy train trucks. Cut off the mounting tab that holds the coupler, and body mount the coupler. That brings me to my first tool recommendations.
<!-- m --><a class="postlink" href="http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=82838">http://www.ares-server.com/Ares/Ares.as ... t&ID=82838</a><!-- m -->
<!-- m --><a class="postlink" href="http://www.kadee.com/htmbord/page120.htm">http://www.kadee.com/htmbord/page120.htm</a><!-- m -->
The first tool in combination with a metal wheel set will make your cars free rolling.
To body mount couplers, most cars today come with some sort of knuckle coupler similar to the Kadee #5. Most of the new couplers will fit a Kadee coupler box, or you can just mount a Kadee #5 coupler (or Sergents or whatever your preference). Choosing your couplers is beyond the scope of what I want to address here. Take a suitable coupler box to mount to your rolling stock, and assemble the coupler/coupler box. Drill a #45 hole in the bottom center of your freight car's end. Tap the hole for a #2-56 screw, and fasten the coupler box to the underside of the car with a suitable length 2-56 screw. that brings us to the second tool on the list, the Kadee coupler height gauge. The Kadee gauge will fit over a section of track, put you car on the tracks and roll it over to couple with the coupler on the Kadee height gauge. When it is right, the coupler knuckles will line up perfectly, and the trip pin will just slide over the top of the little ledge at the bottom of the gauge between the rails.
Now we will presume that all of your rolling stock is compatible in terms of coupler heights and all of it has body mounted couplers. but this one car still derails at one point on the layout. We need to give the car a complete tune up.
The first thing I do is set the car on a piece of track on a perfectly flat level surface. With this test we are checking to see if the car's frame is warped in any way. What you are looking for is for all of the wheels on both sides of the car to sit properly on the rails. You might also want to check the car sitting directly on your flat surface to see if all flanges sit on the surface with no space between any flange and the surface. Athearn 4 bay open hoppers are famous for having warped frames, by the way. If a frame is warped, we can sometimes put it on a flat surface and put weight on the frame like a heavy book and leave it sit overnight to see if it will straighten out. This can only be done with a disassembled kit.
The second test I do with the car still sitting on the track is to check for the frame or body being bent, is the side of the car parrallel with the track?
Are the side frames of both trucks parrallel with the track?
Is there any tendency for either truck to appear to "crab walk" along the track due to one or more axles not being in perfect 90 degree alignment in relation to the truck side frames.
Now roll the car along the track section, is there any sign of a wheel not being centered on the axle indicated by one or more corners of the car going up and down as the car rolls?
Does the car or any of the wheels show signs of wobbling when it rolls on the test track? I have a Bachmann Plus F-7 unit that has one wheel on one axle that is not straight. When that locomotive runs down the track, it wobbles. If you find a wheel that either isn't concentric or wobbles, the only fix is to replace that axle & wheel set.
Now we need the next tool.
<!-- m --><a class="postlink" href="https://www.nmrastores.com/cgi/NMRA_...TION=NEXT+PAGE">https://www.nmrastores.com/cgi/NMRA_...TION=NEXT+PAGE</a><!-- m -->
This is The NMRA gauge. It is one of the most valuable tools you can have in your modeling box for model railroading. It is almost a universal measuring tool for model railroads.
We are going to use it to check the wheel gauge on our car. We need to check each axle individually. If you look closely around the outside of the gauge, you will see some small slots cut in the gauge that are marked for testing wheels for gauge. If both wheels on one axle won't fit into the grooves because the inside of one wheel interferes, the gauge is too tight. If it doesn't fit because one wheel is too wide for the gauge, the wheel set is too wide. Often times the wheels are an interference fit on the axle and by removing the wheels from the truck and twisting them in opposite directions while either pushing in or pulling out, you can adjust the gauge of the wheels.
The next test requires our next link.
<!-- m --><a class="postlink" href="http://www.nmra.org/standards/rp-20_1.html">http://www.nmra.org/standards/rp-20_1.html</a><!-- m -->
This link is to the NMRA recomended standards for weight of cars. find your scale on the chart and the length of the car and you can see what it should weigh. You can get inexpensive postal scales, or an inexpensive scale designed for weighing food portions on a diet. Both will work for what we are trying to do. If your car is too light, add weight to bring it up to the NMRA standard. On closed cars it is easy, you can glue pennies inside to bring up the weight. On open cars it is more of a challenge. You might use a load to add weight. I've used small lead shot gleued in voids in the frame with epoxy to add weight. You might change to metal trucks like a set of Kadee freight trucks to add some weight. You can even take a car apart and replace a steel or zamac weight between the car body and frame with sheet lead to add weight.
LEAD IS DANGEROUS MATERIAL THAT CAN PRODUCE LEAD POISONING IF NOT HANDLED PROPERLY. DO NOT LET YOUR CHILDREN HANDLE LEAD. DO NOT EVER SMOKE OR EAT WHILE HANDLING LEAD. DO NOT PUT YOUR HANDS INTO YOUR MOUTH OR RUB YOUR EYES WHILE HANDLING LEAD. WHEN YOU ARE FINISHED HANDLING THE LEAD, WASH YOUR HANDS THOROUGHLY WITH SOAP AND WATER.
There is one final test that need to be done on our car before we can declare that it is "tuned up."
Turn the car upside down and check the trucks for proper torque or tightness. We want a three point mounting for our trucks suspension system. To get that we want one truck just tight enough that it swivels freely, but doesn't rock. The other truck we tighten the same, then back off just enough to allow the car to rock side to side slightly.
We are done. If you have carefully followed every step in checking out you problem car, and done any corrective repairs needed, you should be rewarded with reliable operation.
Jim Thompson mentioned one other cause of rolling stock problems that I forgot. His post is in the thread a few posts down from this, but I'm going to rewrite it here in order that these first posts at the top of this thread might truly be comprehensive. I brought this post over from the other site, but I left the replies over there, so Jim's original post is still at the other forum.
You may have a car that derails, and when you check it out, everything seems to be in gauge and in spec. as far as weight, truck tightness, etc. The other thing to check is for interference between the truck and the frame, undercarriage, or details. This is especially important with cars with highly a detailed undercarriage, or one which you may have superdetailed the under carriage of a standard kit. The radius that the prototype uses is much bigger than anything we run. It is very easy when super detailing the undercarriage of a car with brake rigging, etc. to have a part that interferes with your truck swivel when negotiating the tightest radius curves on your layout.