# Buckled axles



## Maitai Valley railway (Mar 15, 2012)

A very strange thing has happened to two of my DCC locomotives within this week. Each one was running perfectly satisfactorily for some considerable time on the layout, but they each stopped. When I picked them up to try to determine what was wrong I found the rear axle on both a Kato SD70 and an Atlas B23 had buckled up causing the wheel to jam against the bogie frame and ultimately to seize up with the heat melting the plastic frame against the wheel.
Has anyone experienced anything like this?
Can anyone suggest what may have caused it?
(The locos have never been dropped or damaged in any way.)


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## sstlaure (Oct 12, 2010)

The wheels are typically able to slide on/off a centershaft. It's just a press-fit (removeable by hand) Maybe they simply got worn and started to back out?

Crazy they'd build up so much heat that they'd melt. How long were they running before they stopped?

With it happening on 2 different engines at the same time there MUST be a track issue somewhere that is causing the wheels to go out of gauge. Do you have a track gauge or an inspection car?


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## Maitai Valley railway (Mar 15, 2012)

*Buckled Wheels*

Thanks for your reply Scott.

I may have have given the wrong impression. It was actually a week between the two events. 

Thanks for the info re wheels sliding on/off a centre shaft. I'll explore that. Although I have to confess that the heat has buckled the actual "plastic" bogie.

The trains in each case had done only several circuits of the railway.


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## mopac (Feb 24, 2011)

Its a first I have heard of. Strange with it happening on 2 different brands of
engines. Where you pushing or pulling a long train?


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## NIMT (Jan 6, 2011)

Truly strange, I've been running engines for years and I've yet to have that happen to any of mine??? Makes me think that they have been run or stored in an extreme environment?


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## Maitai Valley railway (Mar 15, 2012)

*Buckled Axles*

Thanks for your replies.

The trains I run are always the same consist of wagons - about 10 bogie wagons behind the SD70 and 8 4 wheel wagons behind the B23.

They have run in that configuration ever since I converted to DCC. They probably run about six circuits of the layout at any time and I have not had any problems in the past.

My train room is well insulated and our weather in Nelson, New Zealand is very equable, running at 19 degrees Celsius to 25 degrees Celsius all summer.

Regards
Murray


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## NIMT (Jan 6, 2011)

Any chance you could post a picture?


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## shaygetz (Sep 23, 2007)

My old Mantuas had a heat issue in their trucks that came from the natural resistance of zinc, brass and steel. They'd get alarmingly hot until I installed axle wipers to bypass the truck frames. These are way too new for that though--and--2 different brands. Quite a stumper...


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## Maitai Valley railway (Mar 15, 2012)

Hello everyone who has replied.
At last I have an answer, from a friend who is into DCC in a big way. When I told him my story he immediately said, Yes, I had that problem with my Consolidation N Gauge loco. Apparently the SB3A booster runs at up to 5 amps, and a short on the track is not enough to cut out, so instead the loco gets up to 5 amps of current, which means that anything melts. Apparently I have to buy a circuit breaker unit and divide the layout into at least three blocks, with separate DCC feeders to each block. Then if I do get a short (such as going over a turnout frog) the amperage will be limited to about 2 amps and things will not get so hot. 

Thanks again for your replies. I will keep you posted as to what I achieve, although it may be a number of weeeks, because I am not going to rush it.

Best regards
Murray


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## xrunner (Jul 29, 2011)

Maitai Valley railway said:


> Hello everyone who has replied.
> At last I have an answer, from a friend who is into DCC in a big way. When I told him my story he immediately said, Yes, I had that problem with my Consolidation N Gauge loco. Apparently the SB3A booster runs at up to 5 amps, and a short on the track is not enough to cut out, so instead the loco gets up to 5 amps of current, ...


No, that makes no sense. The loco doesn't get forced 5 amps of current just because the supply is rated for 5 Amps, it only "gets" the amount of current it's circuitry draws. I've seen this mistake in understanding on the forum before. Example: You connect a 1000 ohm resistor to a 10 V, 1 Amp power supply - it draws 10 mA of current. What happens it you connect the same resistor to a 10V, 100 Amp power supply? Does that make any difference? Not a single bit. Something is wrong with either your friends reasoning or the real cause of the problem.


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## gc53dfgc (Apr 13, 2010)

xrunner said:


> No, that makes no sense. The loco doesn't get forced 5 amps of current just because the supply is rated for 5 Amps, it only "gets" the amount of current it's circuitry draws. I've seen this mistake in understanding on the forum before. Example: You connect a 1000 ohm resistor to a 10 V, 1 Amp power supply - it draws 10 mA of current. What happens it you connect the same resistor to a 10V, 100 Amp power supply? Does that make any difference? Not a single bit. Something is wrong with either your friends reasoning or the real cause of the problem.


No, its basically the engine shorting out on the frogs or from derailments. The engine when running properly or not derailing would only draw what it needs but the second the positive and negative rails get connected through the wheels that are shorting and it basically becomes a heater as it uses as much current as it wants. Because the half wheels are metal connected by plastic it just melts surrounding plastic. I have never had that problem though I do use a 5 amp booster with a 2.5 amp system and it always trips if a train derails or hits a frog wrong but I can see that kind of problem happening, just rare normally.


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## NIMT (Jan 6, 2011)

Just another reason why I like my Digitrax system, I don't ever have that problem!

Maitai Valley railway, You need to check and make sure the Controller shuts down in the event of a short!


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