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Model Railroading > Repair or replace Samhongsa brass RSD-15 trucks?


Date: 10/30/19 19:56
Repair or replace Samhongsa brass RSD-15 trucks?
Author: E25

I have a couple of old ALCO Models RSD-15s that were manufactured by Samhongsa of Korea many years ago.  So far as I can tell, they have never been run on a layout and are in mint condition... very attractive and nicely detailed models with quiet Canon "can" motors.

I have owned these models for at least ten years, but have never tried running them.  To my surprise, when I tried to run them on a test track last week, they wouldn't budge.  After some superficial investigation as to the reason, I ultimately wound up removing the trucks from the locomotive frame and disassembling them.

I was surprised to discover that a previous owner had apparently replaced some of the brass gears with nylon ones, some of which had split, and had also inserted some non-fitting brass gears.  The effect of these changes was to lock-up the gear box and / or result in one or more free-rolling axles due to the fact that the ends of the adjoining gears did not mesh together.  (See the attached photo, below.)

I can probably get the correct gears from NWSL, but I am wondering if it would be better to replace the brass trucks (...which are very nicely rendered) with a more modern tri-mount truck from a six-axle product from Bowser / Stewart, etc.

If I keep the present trucks, should I go with all brass or nylon gears, or a combination of the two?  The existing gear between the "tower" and the first gear in the truck gearbox  is also nylon.

Also, what's a good lubricant to use once I get things working again?

Any thoughts?

Thanks for any suggestions.

Greg Stadter
Phoenix, AZ



Edited 1 time(s). Last edit at 10/30/19 20:08 by E25.




Date: 10/30/19 21:29
Re: Repair or replace Samhongsa brass RSD-15 trucks?
Author: SP4360

I use a product called liquid bearings for both brass and nylon gears. works great.



Date: 10/30/19 22:22
Re: Repair or replace Samhongsa brass RSD-15 trucks?
Author: fbe

The brass gears are not in their proper locations.

If you put the axles in their slots each will need one idler gear in the gearbox to connect to it. That will connect to the next axle or the gear at the bottom of the tower. If you can find one truck which works you can use it as a pattern for others. If you can't find a pattern you might just need to separate the total numbers of each gear size equally amongst the trucks.

The trucks seem to be a quality build I don't think I would replace them.



Date: 10/30/19 22:38
Re: Repair or replace Samhongsa brass RSD-15 trucks?
Author: 4thDistrict

fbe Wrote:
-------------------------------------------------------
> The brass gears are not in their proper locations.
>
>
> If you put the axles in their slots each will need
> one idler gear in the gearbox to connect to it.
> That will connect to the next axle or the gear at
> the bottom of the tower. If you can find one truck
> which works you can use it as a pattern for
> others. If you can't find a pattern you might just
> need to separate the total numbers of each gear
> size equally amongst the trucks.
>
> The trucks seem to be a quality build I don't
> think I would replace them.

Yep, the first two gears on the left are meant to fit on the right of the truck. On the prototype locos the center axle is offset to the right side a bit - it is not centered in the truck so the wheelbase between the center axle and the outboard axles is different. That requires two different sized gears on the model, one size for each side from center. Does the other truck have the correct gears? Maybe they are in the wrong places on that truck as well.

I have four of these locos. The fellow who custom painted them for me replaced the gears with NWSL a couple of decades ago and they have been running well. They are a little noisy, but good runners and pullers.  
 



Edited 3 time(s). Last edit at 10/30/19 22:40 by 4thDistrict.



Date: 10/30/19 23:36
Re: Repair or replace Samhongsa brass RSD-15 trucks?
Author: ts1457

E25 Wrote:
-------------------------------------------------------
> I was surprised to discover that a previous owner
> had apparently replaced some of the brass gears
> with nylon ones, some of which had split, and had
> also inserted some non-fitting brass gears.  The
> effect of these changes was to lock-up the gear
> box and / or result in one or more free-rolling
> axles due to the fact that the ends of the
> adjoining gears did not mesh together.  (See the
> attached photo, below.)
>
> I can probably get the correct gears from NWSL,
> but I am wondering if it would be better to
> replace the brass trucks (...which are very nicely
> rendered) with a more modern tri-mount truck from
> a six-axle product from Bowser / Stewart, etc.
>
> If I keep the present trucks, should I go with all
> brass or nylon gears, or a combination of the
> two?  The existing gear between the "tower" and
> the first gear in the truck gearbox  is also
> nylon.

If the new owner of NWSL can make them, get the correct replacement gears.

I think the nylon gears were original. Typically, surfaces which wear like gears will have less wear with too different materials being used instead of the same material for both sides. However the Samhongsa nylon gears had a bad tendency to crack. 

Other than the wrong placement of the idler gear, I think you have experienced a classic problem with Samhongsa diesels.

I am thinking that the gears were some engineering plastic, not nylon. Anyhow, the plastic and brass gears would alternate, if I recall correctly, to minimize wear.
 



Edited 1 time(s). Last edit at 10/30/19 23:51 by ts1457.



Date: 10/31/19 09:16
Re: Repair or replace Samhongsa brass RSD-15 trucks?
Author: alcoc636

Greg,

If I may be allowed to offer my two cents worth, keep the SAM trucks. As others have suggested, try to get the brass gears matched up. If you are missing any gears, try to obtain replacement brass gears from North West Short Line. I have been using dozens of Samhongsa drive brass diesels on my BN layout for 25+ years. The only downside to the running qualities of these models were their nylon gears. Those nylon gears were cheap and prone to cracking, leading to road failures. Once the gears were replaced with NWSL brass gears, they have become all stars. Yes, they are a bit noisy with all brass gears, but the SAM drive coupled with the Canon motors are a winning combination. They just run and run and pull and pull. My oldest unit, painted and detailed as BN GP9 #1723 has been in continuous service on my BN layout since the late 1980's.

Tim Dickinson
La Verne, CA



Date: 10/31/19 17:11
Re: Repair or replace Samhongsa brass RSD-15 trucks?
Author: Kemacprr

If anyone is interested I have two pair of Samhongsa trucks that I took off two Oriental SDP-45's many years ago. They would not mu with the rest of my then CR diesel fleet. One pair has no gear towers but the other pair has  gear towers and  I retrofitted with 8 wheel pickup. Both have sideframes and original mounts. Would be good for spare parts. Price is free just pay the shipping. -----------  Ken 



Edited 1 time(s). Last edit at 10/31/19 17:15 by Kemacprr.



Date: 11/01/19 17:26
Re: Repair or replace Samhongsa brass RSD-15 trucks?
Author: E25

Thank you one and all for your informative and helpful responses!

It appears that the consensus is that I should keep the original Samhongsa trucks and just replace the gears as needed.

Best regards,

Greg Stadter
Phoenix, AZ



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