# Replace SD40-2 Trucks?



## zr1rob (May 27, 2020)

I'm sorry, but the USA Trains SD40-2 trucks SUCK. That swiveling axle at the front of the truck is the only thing derailing on my entire layout. I like the Aristo SD45 trucks, even tho they have their issues.

So has anyone tried replacing the USA SD40-2 trucks with the SD45 trucks? How did it go? Thanks!


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## Paul Burch (Jan 2, 2008)

I might be wrong but I think I saw somewhere that USA is redesigning the thee axle truck.


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## Michael Glavin (Jan 2, 2009)

This is a common complaint Rob. Dirk had a method of locking up the third axle. I may have saved Dirks floppy axle fix, I'll look around and post here if I can find same. Dirk and I discussed retrofitting our SD40T-2 engines with the Aristo modular trucks and correct side frames. As I recall it was doable, but we never got that far with the project.

I've had great success with ensuring the guide, pin, plate above the floppy axle is lubricated and easily moves. More often than not, this part of suspension system is overlooked, dry and in need of some massage IMO.

Michael


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## Greg Elmassian (Jan 3, 2008)

These and all 3 axle USAT trucks work great. You have an issue that is simple to fix.

It's the lubrication as Michael has pointed out. If dry, or a lot of friction, it will derail in a second. Sometimes the washers are on wrong and add to the friction. Unfortunately the factory usually forgets to grease this.

Grease the plate liberally top and bottom where the "washer sandwich" slides on it... moly grease works best. Grease NOT oil.

I have an entire web page dedicated to this, I would suggest reading it:





USAT floppy axle issues/fixes


Greg Elmassian web site on large scale trains and garden railroads, cigars, and computers




elmassian.com





Greg


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## zr1rob (May 27, 2020)

So I greased the pivot on the truck and the metal slider track above the truck, and it seems to help. I ran the engine back and forth, swapped ends and did it again and no derailments. Thanks for the help!


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## Greg Elmassian (Jan 3, 2008)

After a number of hours running, clean the grease off and reapply.... often there are some high points or roughness on the metal bracket. My early units had very smooth metal and little friction, some of my later locos the metal bracket is rough.

A little grease/oil on the pivoting areas of the truck itself is good, but hard to do with the shell on.

It's a simple thing to take care, but why USAT does not lube this at the factory is beyond me.

Now, also be sure to use a heavy oil on the axle shafts, and grease is best in the journals on the 2 axles that have "tips"...

Even without ball bearings, these locos are pretty tough and run very well. 

Greg


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## ewarhol (Mar 3, 2014)

Found some of Dirk's floppy truck fix photos I have saved in emails. I put the emails and photos in order, here's what he has to say;


In house truck improvement...in process..
"Ma.. it don't turn much now!!"
Smarter this time.. I pre-glued both strips together.. then only one slice
Less parts to handle... faster indeed!
D

Yea.. pretty basic really..
The molded case is not flat... a little flat file helps... course emory board to break surface for glue..
Med CA..
Also.. q tip wash with alcohol... 1st motor blocks are oily...
Makin the glued double strip first made an easier n faster job of it also.. yesterday... I cut the strip in each part...sanded cut end... small pile ready fer a couple more locos now... from just one strip!
Eh... your a Dad n Husband..
Never worry buddy! !
Good morn'n....
Ya could do this... I narrowed the main part width... gives a touch more turning radius... tighter.. this loco goes to a friend that wanted a 8 ft radius... for the loco..
I made the trucks turn inside my standard 5 ft radius the design was worked up to...
Thin you got 4 ft R...
Place truck only on a curved piece of track on bench... we'll talk more!
D


























Here on rails (pretend) set @ a 60" / 5 ft radius / 10 ft circle..
This particular set of trucks is being tweaked to turn a hair tighter than I normally build for myself..
The side stops are 0.010" narrower.
Looking carefully at the single floppy wheel... one can see it is tucked inboard a touch..indicating the narrowness helped it turn a smaller radius...
This tunnel requires a 8ft radius turn as built... #2 tunnel / DRGW.
get'n there!!
















Well. I'm still learning here!! And a good lesson...which will go on the related thread soon..
Having completed one truck...I installed both trucks on the frame.. verified and checked decking/walkway height to rail...64.32"..so that's..well .. great!
Looking them over... my mind on sizing up room for couplers, I find myself playing with the trucks...
I'm pretending the now limited floopy is entering a curve.. leading and actually pulling the rest of the truck into the curve with it.. much like a pony truck does on a steam loco..but I can visualize and play with the other truck... un changed as yet! It can freely lay over side ways in as much angle as it wants..with no influence on the truck proper. It does nothing to lead the following two axles.....it still jack knifes..
Some how... I feel this has to help a loco turn smoother into and back out of curves...
To me at least.. this mod is even more worth while...

D


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## Greg Elmassian (Jan 3, 2008)

Notice complete lack of lubrication on the guide plate?

I don't think that Dirk really completed his investigation, and the mods shown were to handle sharper curves apparently, not the issue here.

Also, I cannot agree that a powered truck works exactly like a pilot truck on a steam loco.

Greg


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## zr1rob (May 27, 2020)

Just wondering, do you have some pix of Dirk's tunnel motors?


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## ewarhol (Mar 3, 2014)

Everything I have a Dirk’s truck modifications I posted. His mods were something he was working on. Michael and Dirk were working on the tunnel model. Not sure if Michael has pictures for that.

Greg, yes the pictures posted were for tighter radii. Dirk had very large radius curves. Why does 20’ radius come to mind?? I also want to think he had his floppy trucks completely stiff, but I’m not 100% sure.


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## Greg Elmassian (Jan 3, 2008)

Yeah, Dirk's curves were so broad he could lock the truck. Also he put traction tires on all axles for pulling power, and used big old heavy gel cells for power. I was concerned that the gearboxes would not stand up, but they were really not long term torture tested.


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