Has anyone experienced with the USA trains SD70 Mac problems with the truck steering not staying on the tracks even around wide radius curves. It seems like the design of the pivot truck is flawed that it’s too light and does not have enough of movement to keep it properly balanced. Maybe extra weight is needed or what USA should have done is what Aristo did with their trucks by having the center wheel pivot back and forth similar to an articulated truck and that is used in other scales too. I also think with the USA design that the truck is off center in which it will make it prone to have these problems of tracking properly. I hope someone is out there that has a fix for this problem so I can bring it up to USA trains with it.
Also it does not derail in the same spot it has nothing to do with the gauge of the rail or the radius or even the code it is the truck does not have enough of swivel movement to properly stay on the track. The reason is they are not heavy enough lack of weight. It would help if the truck side frames were die cast or the under frame that would provide enough of weight to help it track better. Still it would have the problem of the swivel motion. Also The USA SD40-2 has the same type of drive. If you compared the 6 axle Aristo Craft SD-45 and Dash-9 etc. vs the USA 6 axle you will see the powered truck design difference. That is why I am posting this to see if any one else has these same issues with USA trains 6 axle locomotives. As of a fix before I contact USA with the problem and fix.
Well, since you’re hitting all the forums, and not responding to the questions I asked on one, I’ll copy it here:
No, I’ve had a couple through for conversion.
No issues that I can recall.
Don’t these have the curved-slotted guide under the frame?
Have you had anything apart?
Like, reversed the guide?
They are fixed to the frame by that slot, no weight or spring issues to deal with.
How does the pivot axle function with the loco upside down?
Does it swing freely through the arc even when the main truck is turned?
The wheels rotate okay, as in you didn’t drop the driveshaft out?
Does it do this on both thrucks?
Does it do it backing up?
If not, can you see anything assembled differently on either end?
No Conversions I have not taken the trucks apart either.
Curmudgeon said:
Well, since you're hitting all the forums, and not responding to the questions I asked on one, I'll copy it here:No, I’ve had a couple through for conversion.
No issues that I can recall.
Don’t these have the curved-slotted guide under the frame? (Yes they do that is part of the problem not enough of movement)
Have you had anything apart? (No)
Like, reversed the guide? (No)
They are fixed to the frame by that slot, no weight or spring issues to deal with.How does the pivot axle function with the loco upside down?
Does it swing freely through the arc even when the main truck is turned?
The wheels rotate okay, as in you didn’t drop the driveshaft out?Does it do this on both thrucks? (Yes)
Does it do it backing up? (Yes)
If not, can you see anything assembled differently on either end?
I have no idea what are these questions are for but I answered some of them.
TOC is saying,
“Take it apart and fix it.”
That’s what I see with his reply.
USA will never change anything.
TOG
Maybe, maybe not.
If one can invert the locomotive, and by hand run the trucks through the arc, we’ll see if they bind.
On earlier loco, I have seen owners and/or repair shops rotate the slides 180° and they won’t ever stay on the track.
I you don’t have any idea how the trucks work, guide, or stay on the track, best to not even try, just send it back, and don’t be surprised if you later find out it’s your trackwork doing it.
John Bouck said:
TOC is saying, "Take it apart and fix it."That’s what I see with his reply.
USA will never change anything.TOG
I understand that it was copied from another post. My question is what is the fix and how to do it.
As for USA I think they will respond with something since no company wants a bad reputation.
Curmudgeon said:
Maybe, maybe not. If one can invert the locomotive, and by hand run the trucks through the arc, we'll see if they bind.On earlier loco, I have seen owners and/or repair shops rotate the slides 180° and they won’t ever stay on the track.
I you don’t have any idea how the trucks work, guide, or stay on the track, best to not even try, just send it back, and don’t be surprised if you later find out it’s your trackwork doing it.
It’s not the track work since I have Aristo Craft six axle locomotives with no problems. I did see one way to fix it is to re-power it with the Aristo motor blocks but that is way too expensive. As for taking it apart that is not a problem for me I just wanted to find out the best way to fix it without spending a fortune and sending back 10 locomotives is not an option either.
It is not a good design for a six axle truck period you don’t see that in any other scale.
I have known others that have had difficulties with the trucks and they took a couple different ways to fix it. One way is to make the truck rigid. If your radii are large enough that may work. The other is to de-drive the floppy part and add weight to the top.
Warren Mumpower said:Thanks I think that is going to be the way to fix it make the truck rigid and add more weight to it in those areas.
I have known others that have had difficulties with the trucks and they took a couple different ways to fix it. One way is to make the truck rigid. If your radii are large enough that may work. The other is to de-drive the floppy part and add weight to the top.
If it were mine…
Warren has a good idea.
De-power it, then fill it with lead wool. It will act similar to a steamers pilot.
I don’t think I would make it rigid.
.02 worth, or maybe a huppence.
TOG
OBTW,
A friend recently sent all his PA’s in to USA, cause they didn’t perform right. They were causing the power supply to over heat and shut off–(A 20 AMP Bridgewerk), and herky jerky operation, etc.
They sent them back with a note: “Couldn’t find anything wrong with them.”
Hunnert bucks in shipping back and forth down the tube.
You cannot discount the track.
Sorry.
You can have 99 out of 100 pieces of loco or rolling stock pass a point, but one will not.
How do you KNOW it’s not the track?
What is the gauge in the area with a problem?
What is the gauge of the loco?
Gauge of other locos?
Cross level of track at the point of derailment?
Since the pivot axle is held firmly to the slide in the chassis, there IS no spring or weight.
Why does it derail?
It’s a process of troubleshooting and elimination.
I do this every day of the week.
<>
Absolutely! Part of the phun of railroading.
I don’t think I have a virgin loco in my small fleet.
And they are all about to get ravaged more as I install my wireless DCC system.
TOG
Bill,
Those questions are part of Dave’s patented long distance diagnosis technique.
He’s VERY good at this, so trust him. Even if you don’t understand the question he doesn’t ask them unless its important.
Andre’
Bill,
Dave (and I) has seen similar questions on other fora. Given advice, advice was rejected; because it was “impossible” for that being the cause. As far as Dave (or I) is concerned: no problem! You can lead a horse to water, but you can’t make him drink.
Ask for advice, you’ll get it; if you follow it is up to you.
Bill,
As pointed out, you’ve been “shopping” this question on a number of forums.
In one instances you received an almost instant response. That response included a link to a detailed solution, along with abudant pictures, to explain the process of fixing your problem. Then another response offered an alternative solution.
Both of the above mentioned responses would no doubt fix your situation. Either of these solutions would be easy to accomplish and by this time your “problem” could have been solved.
Also, the suggestion to check your track work is very valid.
Seems it may be time to take all this good advice from folks that have been there, done that, to get on with fixing your MAC.
JD
Curmudgeon said:
You cannot discount the track.Sorry.
You can have 99 out of 100 pieces of loco or rolling stock pass a point, but one will not.
How do you KNOW it’s not the track?
What is the gauge in the area with a problem?
What is the gauge of the loco?
Gauge of other locos?
Cross level of track at the point of derailment?Since the pivot axle is held firmly to the slide in the chassis, there IS no spring or weight.
Why does it derail?
It’s a process of troubleshooting and elimination.
I do this every day of the week.
It is not one engine it is all 10 only the USA’s have this problem that is why it is not the track I can buy a new 6 axle from USA trains run it and bam same problem nothing else derails no other engine or car if it was the rail everything would derail then it would be out of gauge and yes I do check my rail for gauge I am not a rookie with model trains either I have been in multiple scales for over 30 years. So I think I would know something about track and scale. I will have to repair the trucks which I should not have to do with brand new locomotives this is what is so frustrating. You should not pay around $250.00 for a new engine then have to correct it because they couldn’t make it right in the first place. All USA trains 6 axle locomotives have the same drive system and it is not as good as some of their competitors period. Aristo does not have Alco PA’s or SD40-2 or SD70MAC etc. so you either have to correct the problem or don’t buy their products. Also I do know some people who work for USA so when I come up with my fix they will know about it and it will get corrected. As I stated before I just wanted to know how many people have this problem and what they did to fix it before I bring it to their attention.
I was running on a friend’s RR the other day, had a car derail in a certain spot each time it went over the spot. The friend insisted that since his stuff never derailed there, it had to be my car. I turned the car around, front to back, as that is often a quick fix, but that did not solve the problem. Finally, I had to take the car off and run without it. I got the car home and checked the wheel gauge, and sure enough, it was just a bit wide. I put the car back in gauge, went back, and another car started jumping the track in that same spot.
I took a good look at the track, and sure enough, there was a very slight vertical curve at the point of derailment. We fixed the vertical curve, and no more problem.
Point being, it could be a combination of factors. Ya gotta look with a “sailor’s eye.” Maybe even use a track gauge on the wheels and track, as well as a level.
The thing with outdoor track is that it always needs attention. Always.
Steve Featherkile said:
I was running on a friend's RR the other day, had a car derail in a certain spot each time it went over the spot. The friend insisted that since his stuff never derailed there, it had to be my car. I turned the car around, front to back, as that is often a quick fix, but that did not solve the problem. Finally, I had to take the car off and run without it. I got the car home and checked the wheel gauge, and sure enough, it was just a bit wide. I put the car back in gauge, went back, and another car started jumping the track in that same spot.I took a good look at the track, and sure enough, there was a very slight vertical curve at the point of derailment. We fixed the vertical curve, and no more problem.
Point being, it could be a combination of factors. Ya gotta look with a “sailor’s eye.” Maybe even use a track gauge on the wheels and track, as well as a level.
The thing with outdoor track is that it always needs attention. Always.
I agree in cases that the track can be the problem and that was the first thing I have checked with several tools. Dial calipers and track gauges etc. and I have found that the wheels and track were in tolerance with in .005 and in large scale that is not much!
This is why In my case it is not the track. I should have been more clear on my part that I have trouble shot everything first.
Also I did check for flange clearance all of the things that could cause the swivel truck to jump off the track.
Yes I did post it on many forums because I wanted to get this out to many people as possible.
I thank everyone so far for the help.
Bill,
the steerable lead axle is a ‘problem’ on the three axle trucks. Surefire fix is to replace with Aristo blocks. As you consider this too expensive (10 locomotives to correct) then the advice here is recommended. Do not overlook the obvious as regards a track problem. Forget verniers and track gauges and actually get down and look at what the loco is doing on the track sections involved. We all have had as much modelling experience as you have and have been there before. No matter how much experience one has, sometimes the obvious is so blatant that we overlook it.
I feel that most who have the USA Trains three axle blocks are well aware of the stated problem. Your multiple postings are preaching to the converted as regards 'getting the message out'. In so far as a 'manufacturer not wanting a bad reputation', then dealing with USA Trains with a service issue is akin to bashing your head against a wall - they simply do not want to know. This is why so many have devised 'fixes' for the problem. As Dave and the other experienced guys have stated, start looking at the 'known' fixes and work from there.My first word was “no”, as in no, in all these years I haven’t sen that.
The issue you describe is not one we normally see.
Occasional oddities as covered in writeups, maybe, but NOT:
10 locomotives.
If ALL 10 LOCOMOTIVES do this from USA and not from anybody else, step one, look at the track.
I have seen a WHOLE lot of issues with wheel gauge in diesels AND STEAM NOT from USA.
Not just gauge.
Cross level.
The chances of you getting 10 locomotives with the same problem, and nobody else has the problem, are, well, fantastic.
"It is not one engine it is all 10 only the USA’s have this problem that is why it is not the track I can buy a new 6 axle from USA trains run it and bam same problem nothing else derails no other engine or car if it was the rail everything would derail then it would be out of gauge and yes I do check my rail for gauge I am not a rookie with model trains either I have been in multiple scales for over 30 years. So I think I would know something about track and scale. "
I think with your “luck” I would stop shopping, flying, or driving across Interstate Bridges.
With the above quote, you have the answers, so I am certain you’ll get it fixed.
BTW, what, exactly, IS the gauge, of the wheels and track, other than "Dial calipers and track gauges etc. and I have found that the wheels and track were in tolerance with in .005 and in large scale that is not much! "