I am having trouble with a new steam locomotive I was given. It is an MTH 4-8-2 Mohawk. It cannot make it through any of my turnouts if attempting to take the diverging track. The first driver wheel climbs up over the frog and then over to the outside of the rail every time on every turnout. The pilot truck goes through just fine. Turnouts are all code 83 atlas snap switch. Straight through or coming out of the diverging track works fine. A locomotive of the same size also a 4-8-2 but made by Broadway Limited has never derailed and continues to run great. I really can't figure this one out and hope someone else knows what to do.
jnl83 I am having trouble with a new steam locomotive I was given. It is an MTH 4-8-2 Mohawk. It cannot make it through any of my turnouts if attempting to take the diverging track. The first driver wheel climbs up over the frog and then over to the outside of the rail every time on every turnout. The pilot truck goes through just fine. Turnouts are all code 83 atlas snap switch. Straight through or coming out of the diverging track works fine. A locomotive of the same size also a 4-8-2 but made by Broadway Limited has never derailed and continues to run great. I really can't figure this one out and hope someone else knows what to do.
I hate to be the bearer of bad news, but your turnouts are too sharp for that loco. Just because a similar loco works fine, that does not mean that one will or should. Every loco design is different.
But back to the track - Atlas snap switches are equal to 18" radius curves, and even if those locos barely operate on 18" curves turnouts are a different story.
Respectfully, please understand that many HO trains are not suited to the toy like 18" curves that come in many sets.
Locos of the size and types you mention should really be operating on curves of at least 24" radius and 30" radius and #6 turnouts would be much better and more reliable.
Please understand that even at 30" radius or 36" radius, our models go around proportionally much sharper curves than real trains and 18" is just too small for many medium to large steam locos - no matter what others or the manufacturer might suggest.
Keep in mind that "minimum" radius rating from manufacturers are just that, and are based on "perfect" conditions that never exist on our layouts - no matter how perfect our track work seems.
Reliable operation is achieved by not pushing these machines to their limits, but by staying in the "comfortable" range of the given tolerances.
Sheldon
Do both engines have "blind drivers" on the center two drivers?
Does one engine have more side play of the axles in the frame?
Are the driver flanges hitting the bottow of the frog?
Just a few things to check.
If the pilot truck tracks but the first driver derails, the rigid wheelbase is too long for the curve radius. The only cure is to keep that loco off the turnouts and curves with too-sharp radii.
The prototype has had to realign and rebuild track to allow long wheelbase locomotives to operate. There are a good many routes which are restricted to short wheelbase locos since realigning them would be either too expensive or impossible.
When the Grande standard gauged the Monarch Branch, they attempted to use six axle diesels to move the rock trains - and found that they couldn't take the 24 degree curves. That branch operated right up to abandonment with four axle diesels.
My own layout has an entire private railway that is embargoed to most mainline locomotives (as well as long freight stock and most passenger cars.) It's the stamping ground of low-drivered teakettles. The higher-drivered JNR 2-6 X locos would go on the ties at the first curve if I ever routed them that way. (I don't.) As for anything with a pilot truck and eight drivers, fuggedaboudit. OTOH, the JNR mainline was laid with curves that allow my long-wheelbase 2-Co+Co-2 motors and 2-8-2s to run without problems.
Chuck (Modeling Central Japan in September, 1964)
All of my curves are about 27" radius using flex track other the the actual turnout. It is only derailing in one direction out of the four possible directions that you can go through a turnout. The pilot truck is not derailing it is the first set of drivers. I've been looking at this thing and have noticed that each driver axle has springs allowing them to move up and down individually, the wheel flanges are significantly smaller and more rounded than the Broadway Limited and the driver wheels are spaced further apart than what my NMRA wheel gauge is showing they should be. The front of this locomotive is significantly lighter than the rear which seems to be lifting the front up somewhat. Is it possible to even out the weight and that might help?
27" radius curves, but what number turnouts are they?
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker 27" radius curves, but what number turnouts are they? --Randy
He indicated in his orignal post they are snap switches, we can only hope he is incorrect and they are actually Custom Line turnouts.
Hopefully a #6 if it is, my T-1's won't do a #4, which is actually a 4.5 frog angle other than at an absolutel crawl, and then only about half the time. A #6, they can traverse at warp speed. Makes sense, since PCM said 22" minimum radius, and it seems when they say a minimum, they really mean it as absolute minimum.
Its hard to tell for sure what turnouts the OP is referring to.
Atlas makes a code 83, 22 inch radius switch, as well as the #4 frog switch. I have a couple of each, and they're indeed different. I don't think they make a code 83, 18 inch radius switch. I think the 18 inch radius traditional snap switch is code 100.
- Douglas
rrinker Hopefully a #6 if it is, my T-1's won't do a #4, which is actually a 4.5 frog angle other than at an absolutel crawl, and then only about half the time. A #6, they can traverse at warp speed. Makes sense, since PCM said 22" minimum radius, and it seems when they say a minimum, they really mean it as absolute minimum. --Randy
I know what you mean, I have two Reading T-1's as well. I found they tracked much better after I added weight in the smoke box (left emty for a future smoke unit I assume) and modified the tender so the drawbars did not bind when close coupled.
I have a large fleet of Spectrum USRA Heavy 4-8-2's that don't really like anything less than a #6 as well. Except for water front industial areas, all my turnouts are #6 and #8, all Atlas code 83 except for a few Walthers double slips.
Those Snap switches work out to about a #3.5 - too sharp for anything but a GE 70 tonner and few box cars.
Sorry about the confusion. They are actually #6 code 83 turnouts. Just tried adding weight and it fixed the problem. There must not be enough weight on the front driver axle and because of the springs it just lets that axle ride up over anything that it doesn't like. I just sat a small box of nails on top of the boiler and tried it and ran through perfectly. Now I just have to figure out where I am going to put the weight inside since I would rather not run it all the time with a pack of nails sitting on top.
jnl83 I am having trouble with a new steam locomotive I was given. It is an MTH 4-8-2 Mohawk. It cannot make it through any of my turnouts if attempting to take the diverging track...
I am having trouble with a new steam locomotive I was given. It is an MTH 4-8-2 Mohawk. It cannot make it through any of my turnouts if attempting to take the diverging track...
You say it won't take any of your turnouts, but your curves are fine. It won't negotiate any of those multiple turnouts' diverging routes, but the through routes are assumptively fine. That leaves only two possibilities:
a. the diverging routes are too sharp for the rigid wheel base of the drivers, but not for the pilot truck; or
b. the driver gauge in at least the leading axle is outside of the tolerance acceptable by the structure of the turnouts you are using.
Note that I am assuming that the turnouts are not bowed due to the tendency of some to present with a dip or a hill over time as the plastic base of ties and webbing changes over time. Especially bad is the EZ-Track from Bachmann, although it has the fake plastic ballast as well, a major contributor to the eventual and inevitable deformation.
Crandell
With sprung drivers the engine weight should be balanced between the 2nd and 3rd driver. The pony and trailing trucks carry no weight and are along for the ride only. Having one end heavy can reduce traction by lifting one end on the loco. Does your engine back thru the turnout? Also the out of gauge driver may contribute to your problem.
I had an experience with a BLI 2-8-2 where the drivers "climbed" a bit through Atlas code 83 90-degree crossings. Used a NMRA gauge to check the wheel flanges not too thick or high, then checked the clearance between the guard rail and rail, etc. The depth was ok but the guard rail to rail distance was tight, causing the drivers to climb a bit and the loco walk over the crossing without derailing. My point...check the turnout clearances to ensure the clearance is not too tight and contributing to your issue.
Paul
Modeling HO with a transition era UP bent
It will back through the turnout with no problem, issue is only happening in forward motion. It seems from the weight distribution that the locomotive is balancing on the 3rd and 4th drivers, which is not the middle of the locomotive. It seems to be having a see-saw affect by pushing the rear of the locomotive down and lifting the front. I have never seen this happen even on supposedly "cheaply" made models. I thought MTH was supposed to be the higher end of engines. Has anyone ever opened an MTH steam engine up to see how much room is inside for adding any weight to the front half?
What you've encountered is a problem fairly common to locos which have sprung drivers that aren't equalized. The springs can't transfer weight from the rear drivers, which is what the equalizing system is designed to do. In addition, compare that little coil spring to the all-but-rigid leaf springs of a prototype loco.
A few craftspeople have built fully-equalized HO steamers, usually on a one-off basis. The closest any production model ever came to equalization was the (I think) Varney system, which ran tight cables over all the driver axle boxes on each side and tensioned them with fairly heavy miniature screen door springs.
I remember being told that a properly equalized loco without springs was preferable to one that was sprung without equalization. Unfortunately, the manufacturers weren't listening. They still don't have a clue.
tomikawaTT What you've encountered is a problem fairly common to locos which have sprung drivers that aren't equalized. The springs can't transfer weight from the rear drivers, which is what the equalizing system is designed to do. ... I remember being told that a properly equalized loco without springs was preferable to one that was sprung without equalization. Unfortunately, the manufacturers weren't listening. They still don't have a clue. Chuck (Modeling Central Japan in September, 1964)
What you've encountered is a problem fairly common to locos which have sprung drivers that aren't equalized. The springs can't transfer weight from the rear drivers, which is what the equalizing system is designed to do. ...
Chuck, you were told correctly! I was told that many years ago, and I also was told that a loco with super stiff springs would track, and pull better than one with soft springs. It has worked for me.
But to the OP, if your drivers are not in gauge, you say they are wide, you'll always have the problem of derailments on turnouts and other trackwork until they are put into proper gauge.
Carey
Keep it between the Rails
Alabama Central Homepage
Nara member #128
NMRA &SER Life member
Add a little temporary weight on top of the front of the boiler and see how it responds.
Jim
Thanks for all the suggestions. Is setting the wheels to the proper gauge something that can be fixed? If so, should I be able to do that myself? Is there anything I could possibly do about the springs? Such as replacing them with a different kind or getting rid of them altogether? They really seem to be more trouble than they are worth. I'm coming from O gauge and never had any of this nonsense, maybe I should go back
tomikawaTT What you've encountered is a problem fairly common to locos which have sprung drivers that aren't equalized. The springs can't transfer weight from the rear drivers, which is what the equalizing system is designed to do. In addition, compare that little coil spring to the all-but-rigid leaf springs of a prototype loco. A few craftspeople have built fully-equalized HO steamers, usually on a one-off basis. The closest any production model ever came to equalization was the (I think) Varney system, which ran tight cables over all the driver axle boxes on each side and tensioned them with fairly heavy miniature screen door springs. I remember being told that a properly equalized loco without springs was preferable to one that was sprung without equalization. Unfortunately, the manufacturers weren't listening. They still don't have a clue. Chuck (Modeling Central Japan in September, 1964)
Chuck makes some great points here.
And based on my 40 plus years of experience with this stuff, sprung drivers are, as Chuck suggests, not automatically a plus.
Some of the best traking and best pulling large or medium steamers out there have hybrid suspensions in which only some drivers are sprung and others have some vertical travel but no springs.
One of the best examples is the Bachmann Spectrum USRA Heavy 4-8-2.
Generally such a design allows most of the weight to bear on only two drive axles while the others are lightly sprung to allow them to track well.
Several other Bachmann Spectrum models have similar designs, some don't even use any springs but purposely load the loco weight onto only two of three or four driver axles.
One perfect example of a not so perfect loco with sprung drivers are my two PCM Reading T-1 4-8-4's.
These locos had a large empty space in the smoke box for future smoke unit versions, but this left the loco unbalanced and very "bouncy" on the rear driver. On large curves and turnouts this was not readily noticeable and did not cause problems. But when I tired to run them on friends layout with sharper curves, a number of derailments occurred - on a layout built by an NMRA master modeler with excellent hand layed track.
I took them home and proceeded to add weight to balance the loco - problem solved. They track and run very well now.
All drivers sprung but with poor weight distribution did not run as well as one driver sprung and correct weight distribution as on the Spectrum Heavy 4-8-2. Without traction tires the Bachmann model pulls more as well - it has better adhesion.
I have no experience with MTH, nor am I likely to based on their pricing, choice of prototypes and built in control system, but I would be examining the balance issues with that loco if it were mine.