Thanks to everyone, I see I have some work to do with the steam trains and will do my best to figure out the problems or it looks like the steam era will be over quicker than it was in real life.
JOHN MACLEOD I have just recently added 2 new steam engines to my layout. A 2-10-2 and a 4-8-4. When going around a curve the front trucks want to lift up and jump the track. Not always! It seems to me that the trucks do not have enough weight to stay on the track as they go around the curve and the wheels run up and jump. I have a few ideas but would like to hear if others have had this problem and what was done to resolve it, Thanks.
I have just recently added 2 new steam engines to my layout. A 2-10-2 and a 4-8-4. When going around a curve the front trucks want to lift up and jump the track. Not always! It seems to me that the trucks do not have enough weight to stay on the track as they go around the curve and the wheels run up and jump. I have a few ideas but would like to hear if others have had this problem and what was done to resolve it, Thanks.
John,
Warning: Lengthy response.
I looked at the configuration of the leading trucks of your locos on the Bachmann parts site to see if there were springs involved. Answer--No. The first thing I do if any of my pilot trucks hit the ground (I have very generous 36 inch curves, have transition curves, and no vertical defections in the trackwork) is to put the locomotive on a flat surface--I use a piece of glass--and see if all wheels sit on the surface as they should. This detects any twist in the mechanism for any reason.
Now for the pilot, I check that all flanges are on the glass, THEN I see how much I can lift the wheels off the glass using my fingers or whatever. If you cannot lift the leading truck a bit without also lifting the drivers, then you have a problem with not enough vertical (upward) play. In this situation, any vertical track deflection could put enough abnormal force on the pilot to derail it because it has no where to go upward.
OK, if this test is fine, the next question is 'how much upward play in the pilot to you have?'
If a lot, I remove the pilot from the frame and carefully bend the arm downward so the wheels have more downward pressure on the railhead. This is the force that would be generated by a spring or weight.
Certainly when there is room, as others have said a little weight is good, but if not or you can't tell, the added weight can snag somewhere and make things worse.
Another thing is that if there is a twist in the pilot relative to the driving wheels, no amount of weight will solve the derailing problem.
Sometimes the answer is not in the obvious, but lurks in the shadows of small (but significant) details.
P.S. Should not be too hard to manually set (read bend) the pilot arms going by the pictures I dug up on the Bachmann site because the arms are plastic. If you decide you want to reset the plastic arms, try running the arm under hot water a bit to make the plastic arm a bit more--well--plastic!
Oh, lastly, check for moulding flash around the pilot truck arm mounting hole to make sure you are getting a free swing.
Good luck in finding your issues.
Joel
Modeling the C&O New River Subdivision circa 1949 for the fun of it!
Without even asking I'm betting they are both Bachmann standard line locos. I have both of them. The 4-8-4 Niagra is the worst piece of junk I ever put on any layout. There is no way that front truck is going to stay on the track. I tried all sorts of adjustments and nothing worked. It has earned a permanent place as a static model in my engine terminal. Their 2-10-2 has operated OK but a long time ago I had a Bachmann Consolidation with the same problem. Never could get the front truck to work so finally I removed it and made it a 0-8-0. I have two Spectrum Consolidations which work great and are two of my favorite locos.
Edit: I should have mentioned I run 36" radius curves and my mainline turnouts are #8s.
JOHN MACLEOD My curve radius are 22 and up. My Bachmann is the 484 and can run on 22 curves.
My curve radius are 22 and up. My Bachmann is the 484 and can run on 22 curves.
Rich
Alton Junction
My curve radius are 22 and up. My Bachmann is the 484 and can run on 22 curves. It is a bigger engine than my Mahano 2102. I am going to see about adding a little weight to the 484. The 2102 run for the most part very well. A few track areas will be looked at for both. I have no issues with any other locos. These are not as forgiving as the rest of my engines.
Let me add that on tight curves, the driver wheels press against the inside of the outer rail, lifting the pilot truck up off the rails.
I never had much luck putting weight on the pilot truck. The real problem is the radius of the curve.
Use a factor of 3.0 to determine minimum radius and a factor of 3.6 to determine trouble free radius. Multiply that factor by the number of driver wheels. So, the minimum radius for a 2-10-2 is 30" radius (10 x 3.0), and the trouble free radius for a 2-10-2 is 36" radius (10 x 3.6). The minimum radius for a 4-8-4 is 24" radius (8 x 3.0), and the trouble free radius for a 4-8-4 is 28" radius (8 x 3.6).
I have that problem on one spot. I have a Bachmann 4-8-4 and 22 inch radius curves. It takes all of the curves fine except one where the track has the slightest little lift where the roadbed has warped right at the splice making the track uneven. It that point the front truck lifts up. It usually falls back down and then causes the first driver to derail. I’m pretty sure the problem is all about the track work not the loco unless the wheels are slightly too wide, like most of the Athearn blue box tunnel motors which I’ve bought lately. They hate that corner until I fix the wheels by putting them closer together.
Check your superelevation as you go through the curve...if you go from + to - anywhere in the curve you risk these kinds of derailment. I find these superelevation "wobblies" are pretty common.
redvdub1
Often adding weight makes a big difference. Often it's that simple, too. However, as the other responders have suggested, maybe there is more to it. Curvature radius is important. So is the condition of the track. Things such as gauge pinches, rails uneven in height along a given radius from the center of the curve, maybe super-elevation that is too sudden, or even improper heights across the gaps at joints between rail segments. Maybe there is a rough finish or flashing left from the machining in the area of the bearing or pivot for the affected truck. Axles can be installed incorrectly, or wheels improperly placed on the axle.
For example, the axle should look like this in profile from above:
<=[{======}]=> and not like this: <==[{======]}> still in gauge but both slid to the right. That axle won't track well on the rails close to the other axle in the same truck.
Get some strong light on the subject area where most derailments take place, and run the locomotives back and forth slowly. Watch for the first signs of lifting out of the gauge. It might not be the truck at all, but the long rigid frame behind it being tilted/rolled by uneven tracks back at the last set of drivers.
Curve radius is important. If it's too sharp, you're asking for trouble. Most 2-10-2 and 4-8-4's will handle curves of 24" radius or more, although they don't usually look very good doing it. If the curve isn't excessively tight, the usual fixes are increased weight on the truck and/or adjustment with some sort of spring.
Tom
I have a Bowser 4-6-2, HO. I had the same problem with the leading truck, I was running on 22" and 24" curves. I added lead to the truck as best I could never stoped it altogether, i wondered if the drive wheels did not have enough side to side play.
I gave up and haven't run that loco in some time. Not what you want to hear I know, I will be interested to see what others suggest.
What is the curve radius involved? Also what locomotive brand? Going out on a limb and going to say Bachmann, but want to know for sure.