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Motorizing an Athearn RDC

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Motorizing an Athearn RDC
Posted by John-NYBW on Sunday, July 31, 2022 12:19 PM

A few years ago I bought a pair of Athearn RDC units at a train show. The baggage/express unit was powered and the coach was dummy. A few months ago I opened up the powered unit to see what it would take to convert them to DCC and discovered it has a rubber band drive. I tried running it in DC mode and it had a herky-jerky movement to it. I'm thinking the best option would be to replace the motor and trucks but I've never done such a conversion and I'm wondering what might be a good replacement for what is in the powered unit.

I clicked on the Bowser ad at the top of this page because it showed such a motor and trucks but all it did was take me to their home page and I can't find the item that was in the ad. 

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Posted by maxman on Sunday, July 31, 2022 12:58 PM

Remove the guts, turn them into dummies, and couple them to a Proto 1000 powered unit?

Don’t know about Bowser. Probably easier to call them and ask tomorrow.

However, there was an outfit called Ernst that made a re-gear set specifically for the Athearn RDC.  Look in the Walthers on-line catalog for item 259-3. Out of stock but you’ll probably find one if you search.

Tried one of them once and didn’t have much luck.  Probably not patient enough.

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Posted by doctorwayne on Sunday, July 31, 2022 2:02 PM

North West Short Line offers a number of power drive-units in their catalogue, including ones for re-powering a variety of manufacturers' locos.  My catalogue is an older one, but it shows at least one power truck made specifically for an Athearn RDC.

Wayne

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Posted by sandusky on Sunday, July 31, 2022 2:06 PM

Keep in mind these are shorties and, as such, will not match the Rapido units. All factory Athearn RDCs were rubber band drive, as far as I know.

 

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Posted by AntonioFP45 on Sunday, July 31, 2022 2:16 PM

Hi John,

Please don't take this negatively but..............for the amount of money that you may wind up spending to remotor this unit; you're likely better off purchasing an LL Proto 1000 RDC on the secondary market.  Quite a number of them pop up on ebay for resonable prices in the $40 to $70 range  (inspite of the current economy).

They're VERY easy to paint strip and customize. Plus they're heavy and generally run smoothly.  I currently have two.

 

"I like my Pullman Standards & Budds in Stainless Steel flavors, thank you!"

 


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Posted by ATLANTIC CENTRAL on Sunday, July 31, 2022 2:20 PM

I did six of them with the ERNST drive, wheels from NWSL and new can motors, they run pretty well.

But it was a lot of money and work, and they required a lot of weight to help them run smoothly becuase the low gearing gives them realistic speed but lots of torque..

I don't think ERNST makes any of that stuff any more?

 

 

 

NWSL also sold some power trucks, not sure what they are selling now, that could be used for this sort of thing.

Sheldon 

    

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Posted by Autonerd on Monday, August 1, 2022 2:08 AM

NWSL's power truck was called the SPUD - Self Propelled Underfloor Drive. They're out of production now, but my local hobby shop, Train Shack in Burbank, had one in the used cabinet a couple of weeks ago -- Google and call them (feel free to tell 'em Aaron sent you). That said, I don't know if that's the right SPUD for an Athearn RDC, or how/if you can convert them to DCC, or if one SPUD can pull two RDCs, or anything like that. But it's a lead!

All of that said, I agree that the Athearn RDC, cool as they may be, are a lot of work for a not-so-great model. I think trying to find a Proto 1000 RDC is a better idea in terms of money and time. They are prototypical length and are overall nicer models than the old Athearns, which I think date back to when the real RDCs were new! And if money is no object, the Rapido RDCs are gorgeous! I can't afford one but I've played with someone else's, and... wow, wow, wow.

HTH

Aaron

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Posted by gmpullman on Monday, August 1, 2022 2:15 AM

Good to see you back, Aaron! Yes

I had three of the Proto 1000 RDCs and while they do run very smoothly they are notoriously s-l-o-w. Top speed is about 40-45 SMPH.

NWSL does offer a speed-up gear set if you decide to go the Proto route and are annoyed by the non-passenger speed. If I recall the Budd RDC could attain 85 MPH.

Good Luck, Ed

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Posted by John-NYBW on Monday, August 1, 2022 5:30 AM

Autonerd

All of that said, I agree that the Athearn RDC, cool as they may be, are a lot of work for a not-so-great model. I think trying to find a Proto 1000 RDC is a better idea in terms of money and time. They are prototypical length and are overall nicer models than the old Athearns, which I think date back to when the real RDCs were new! And if money is no object, the Rapido RDCs are gorgeous! I can't afford one but I've played with someone else's, and... wow, wow, wow.

HTH

Aaron

 

I can afford a new one too but for the limited amount of use it will have in my operating scheme, I can't justify the cost. Lots of used offerings on ebay to choose from at a fraction of the cost of new.

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Posted by snjroy on Monday, August 1, 2022 6:05 AM

Hi there. How about taking the mechanism from a Bachmann doodlebug? It appears to be the appropriate size. With patience, you can find one used that won't break your budget. The Athearn looks nice at shorter length on right curves...  You could connect other dummies to it and make a nice set. 

Simon

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Posted by wjstix on Monday, August 1, 2022 9:38 AM

sandusky
All factory Athearn RDCs were rubber band drive, as far as I know.

I think the rubber band drive were just the earliest ones from when they started offering them around 1960? I think the RDC I bought in the 1990s had more normal 'blue box' gearing, though it's been in storage a long time (since the Proto RDC came out soon after I bought it, and I bought a couple of them).

Stix
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Posted by John-NYBW on Monday, August 1, 2022 9:50 AM

snjroy

Hi there. How about taking the mechanism from a Bachmann doodlebug? It appears to be the appropriate size. With patience, you can find one used that won't break your budget. The Athearn looks nice at shorter length on right curves...  You could connect other dummies to it and make a nice set. 

Simon

 

I have thought of that since I have a couple those already that are not in use including an undecorated one that's ONB. If I remember right I bought them from Trainworld at a close out price. I tried converting one to DCC and it didn't go well. I can't remember the issues but the guts are now in the box along with the shell and the bottom. I don't think the powered truck would be right for an RDC although I haven't looked at it in a long time. 

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Posted by snjroy on Monday, August 1, 2022 11:14 AM

OK, so since you have the parts, you could explore the issue. 

Looking at the doodlebug layout (I found it on HOseeker), the rear truck is basically a swivel-base truck.

https://hoseeker.net/assemblyexplosionbachmann/bachmanemcgaselectricdoodlebugpg2.jpg

So changing the length should be easy if you need to do that - just cut the frame and drill a new hole for the dead truck, if I see that correctly. You just need to see how the Athearn body fits over that frame. The dremel might be useful here. You might also have to glue some angles on the Athearn body if it is too wide.

As for DCC, I can't see how that would be a problem. The version I saw seemed to be DCC ready. If not, you can easily hardwire a decoder. You need to make sure that the motor is isolated from the power pickup wires (wheels). I'm guessing it already is if you cut the power leads on the motor. You can test that with an Ohmmeter - just touch the motor and see if there is resistance between the motor armature and the wheels. If there is no conductivity, then just install the decoder as instructed by the manufacturer (red and black wires on power pickups, orange and grey on the motor leads, blue-white-yellow for the lights).

Anyway, up to you to see.

Simon

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Posted by Ron High on Monday, August 1, 2022 12:05 PM

One improvement to the old Proto RDCs is to remove the diode bridge that is used for constant lighting , replace the headlight bulbs wit LEDs. There is a voltage drop to the motor because of the diode bridge. this will increase the speed by about 10 MPH. Beyond that  aremotor with an higher RPM might help.

Ron High

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Posted by Ron High on Monday, August 1, 2022 12:11 PM

Antonio what did you use to paint strip the Proto RDCs. I would like to do several and repaint them using yor Alclad method?

Ron High

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Posted by ATLANTIC CENTRAL on Monday, August 1, 2022 4:41 PM

wjstix

 

 
sandusky
All factory Athearn RDCs were rubber band drive, as far as I know.

 

I think the rubber band drive were just the earliest ones from when they started offering them around 1960? I think the RDC I bought in the 1990s had more normal 'blue box' gearing, though it's been in storage a long time (since the Proto RDC came out soon after I bought it, and I bought a couple of them).

 

Really? I would like to see a picture of the inside of a geared RDC from Athearn produced in the 90's. I worked in the business and have never seen such a thing.

RDC production stopped for many years during the 80's, then there was one last run in the mid 90's - flywheels added to the motor, still rubber band drive, at only $23.50 each.

The story is that during that last run, there were problems with the tooling that prevented future runs without retooling which Athearn simply was not going to do. The plastic version of the RDC came out late in 1957 and there was a metal gear drive version before that.

Sheldon

    

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Posted by AntonioFP45 on Monday, August 1, 2022 5:54 PM

Hi Ron!

I don't want to hijack this thread so I'll answer briefly. After disassembling the shell, submerge and soak it in either 91% Iso-alcohol or the purple "Super Clean".  Message me any time if I can be of assistance.

 

Ron High

Antonio what did you use to paint strip the Proto RDCs. I would like to do several and repaint them using yor Alclad method?

Ron High

 

"I like my Pullman Standards & Budds in Stainless Steel flavors, thank you!"

 


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Posted by Autonerd on Monday, August 1, 2022 7:27 PM

Hi Ed! I owe you an email -- your Mamiyas and I are getting along swimmingly!

All this talk of RDCs has got me thinking... and shopping. A Proto 1k with sound sure sounds neat. Does anyone know if the newer DCC-ready units are any quicker? And to they have the voltage-drop issue mentioned below? 

Aaron

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Posted by BroadwayLion on Monday, August 1, 2022 8:54 PM

I took the power out of my RDCs and re-purposed them as cab cars on some push-pull routes.

The Route of the Broadway Lion The Largest Subway Layout in North Dakota.

Here there be cats.                                LIONS with CAMERAS

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Posted by SeeYou190 on Tuesday, August 2, 2022 8:51 AM

wjstix
I think the rubber band drive were just the earliest ones from when they started offering them around 1960? I think the RDC I bought in the 1990s had more normal 'blue box' gearing, though it's been in storage a long time

I have never seen an Athearn RDC with anything but rubber band drive.

I have two I am going to power. One will have NWSL power truck. The second will be a power/trailer combo (A'la ATSF), and the lead power truck will be from an Athearn GP-35.

-Photograph by Kevin Parson

Hopefully the small windows in the front will hide the Athean GP35 motor and power truck.

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

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Posted by xdford on Tuesday, August 2, 2022 6:09 PM

While it sounds crude, I made an adaptor for an Athearn switcher truck to fit inside a frame I had been given which had already been altered. I did try the same size wheels but it was too close to rail level and the darker underframe is not noticeable at regular viewing distance. 

I have had a number of motors in it from the original Athearn motor turned on its side, a Mabuchi can motor, a vending machine motor and have had it running with a Canon motor driving the one truck.  The Canon was/is  best of all. It runs as well as the Proto I have - which looks silly on my curves- but closer to prototype speeds.  

PM me if you think a photo might help,

Cheers From Australia

Trevor

Editor Railway Modeller Australia magazine

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Posted by John-NYBW on Thursday, August 4, 2022 2:57 PM

SeeYou190

 

 
wjstix
I think the rubber band drive were just the earliest ones from when they started offering them around 1960? I think the RDC I bought in the 1990s had more normal 'blue box' gearing, though it's been in storage a long time

 

I have never seen an Athearn RDC with anything but rubber band drive.

I have two I am going to power. One will have NWSL power truck. The second will be a power/trailer combo (A'la ATSF), and the lead power truck will be from an Athearn GP-35.

-Photograph by Kevin Parson

Hopefully the small windows in the front will hide the Athean GP35 motor and power truck.

-Kevin

 

That's an interesting idea. I think I have a few retired Athearn BB locos that I could try to repurpose to power one of my RDCs. It's been a long time since I looked under the hood to see what it would take to do such a conversion. I'm thinking it should only be necessary to power one truck although picking up power from both trucks would make it less prone to stalling over unpowered frogs or dirty spots on the track. 

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Posted by ATLANTIC CENTRAL on Thursday, August 4, 2022 5:27 PM

When thinking about using a drive from a regular diesel loco, keep this in mind.

The prototype RDC truck has an 8'-6" wheelbase and 33" wheels, Athearn I believe used the correct wheelbase but with a 36" wheel from their passenger cars.

A Bloomberg diesel truck hasa  9'-0" wheelbase and 40" or larger wheels.

So transplanting the RDC sideframes to the diesel truck will be problematic.

Sheldon

    

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Posted by SeeYou190 on Sunday, August 7, 2022 9:49 AM

John-NYBW
I'm thinking it should only be necessary to power one truck although picking up power from both trucks would make it less prone to stalling over unpowered frogs or dirty spots on the track. 

That is exactly my plan. I also intend to add some roof details like perhaps a couple of EMD rectangular stacks and a winterization hatch in the F-Unit style.

EMD Made the 567 diesel in an 8 cylinder version. I think it would have one of those and be half of a GP-9!

Welcome to my world of nonsense!

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

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Posted by John-NYBW on Sunday, August 7, 2022 11:12 AM

I just received the P1K RDC I bought on ebay and now see how much the Athearn ones are shortened. I bought these on a whim at a train show and didn't pay a lot for them but now have to decide if it is worth it to motorize them and add a decoder, especially now that I have a full sized one. Until I made the impulse buy, I hadn't planned on having any RDC units. I'm thinking they could just run from the staging yard to my main passenger station and then back into staging. 

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Posted by ATLANTIC CENTRAL on Sunday, August 7, 2022 3:05 PM

What road name are your Athearn RDC's? Let me know if they need a new home.

Yes, the Athearn RDC is about 72', the prototype was 85'. The other spotting difference is the radiator housing on the roof. On the Prototype, and the correct length models, it is off center. The compressed Athearn model has it in the middle.

While I do have some 80' heavyweight cars, I avoid 85' passenger cars, even with my large curves. It would take 48" radius and another 500 sq ft to tempt me into 85' passenger cars...... I don't see that happening.

The whole selective compression thing depends a lot on your goals, and the kind of scenery you build in my view. My layouts have mostly been built with most/much of the train viewing at 3-6 feet away. 

A train of 72' cars, on large curves, 6 feet away provides a bit of forced perspective......

Sheldon

    

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Posted by John-NYBW on Sunday, August 7, 2022 8:09 PM

My Athearn RDCs are both B&O. A dummy coach and powered combine. I disassembled the mechanisms on the powered unit to see what it would take to convert them to DCC but I should be able to put the parts back the way I got them. 

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Posted by SeeYou190 on Sunday, August 7, 2022 10:03 PM

I have three Athearn RDCs, and one Rapido RDC.

With my layout size, and curve radius, the Athearn models are better suited.

-Kevin

Living the dream and happily modeling my STRATTON AND GILLETTE Railroad in HO scale. The SGRR is a freelanced Class A railroad as it would have appeared on Tuesday, August 3rd, 1954, in my personal fantasy world of plausible nonsense.

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Posted by ATLANTIC CENTRAL on Sunday, August 7, 2022 10:22 PM

John-NYBW

My Athearn RDCs are both B&O. A dummy coach and powered combine. I disassembled the mechanisms on the powered unit to see what it would take to convert them to DCC but I should be able to put the parts back the way I got them. 

 

I model the B&O....... And I would not mind a couple more RDC's.

Sheldon

    

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