Looking for RDT Truck or Motor

Hmm.  I noticed this same effect with a Lionel Yard Chief (6-8516) and one of the later 2-6-4's (18625).  The cogging effect was very pronounced when the locomotives were new, but eventually weakened as the locos accumulated running time.  I wonder if it could be weakened faster by zapping the motor with a short burst of AC (I'm guessing that's what happens as the motors are subject to poorly-filtered, rectified DC over a period of several years.)  

You could also try ordering a new motor of this type from the Lionel parts dep't.  If the pinion gears aren't the same, you'll have to swap them.  Or you could order a complete low-profile power assembly from a LionChief+ RS-3, which is a larger motor with a worm gear drive powertrain.

Personally I never liked the setup in your photo.  I was glad when the "big three" retired their sidewinder drives.  My $.02.  -Ted

Heven't checked out the LC RS-3 drive (sounds like a good project unit), but I like the

"sidewinder" (as you call them) drives, warts and all. The gear ratio is too high, but

they will run fairly slowly if you try. They are compact. They tend to be durable when

not asked to pull overly heavy trains.

But mostly I like the fact that they have a traction motor, in the truck, using helical gears - just like the real thing (no worm gears in the real locos.)

I don't want to order a new motor "in the dark", as I'm likely to end up with the same thing I have, and I'd have less money in my pocket.  Same for ordering a new truck assembly, I want to know for sure what I'm getting. 

I can't use a larger truck assembly, the low profile of this one is why I want to use it. Out of curiosity, I checked for that one, but they don't list parts for the RS-3.

As for zapping it, I can't imagine that fixing this issue, Jon Z. at Lionel stated it was just a different motor design and it wasn't compatible with the cruise systems.  I am looking for something similar that doesn't have the pronounced poles as you rotate it. 

John, what are the dimensions of that motor? Diameter, length, and shaft diameter would help. I can check my stash.

Pete

The gear is .34" outside diameter, and has 12 teeth.

Total shaft extension is .46".

Shaft diameter is .080"

Motor diameter is .950"

Motor length is 1.2" exclusive of the terminals.  There is a .060" collar on the gear end that is .25" in diameter.  That's included in the shaft length.

There are two screws on opposite sides of the shaft on the face of the motor to hold it in place.

Is this close enough ? You can have the whole thing if it will

work for you. I bumped it with a 9volt battery and the motor is good...

Bruce..

That looks just like what I have, so it would clearly work.   Does it rotate fairly smooth without significant detents when you spin the wheels (and the motor)?  If so, I'd love to have it.

Hmmm.... I wonder what John is working on now? Another Weinermobile-style project perhaps? Can't wait to see it! 

The gears are a little gummed up but I'm sure it will work.

Send me your mailing address to stoshu@wideopenwest.com

and I'll get it to you in the mail this week...

P.S. You've done so much for me and everyone here it's free...

Bruce..

Top secret.

John, I have a new 6008903120 Lionel motor for that truck.

it turns nice & smooth. Let me know if that will work for you.

John

John, the question is, does the gear match up with what I have?  I know that some of the Lionel trucks that were similar to the K-Line had a different sized gear.

The gear is .34" outside diameter, and has 12 teeth.

The motor is the same but the gear is 10 teeth. If you can't find the right one you can maybe change the gear.

John (Lionel Parts),

The part number you gave for the motor has "8903" in it.

I'm curious... was this motor originally spec'd for the 2-4-2 Columbia from the 1979 "Black River Freight" set, or the Amtrak Alcos from the 1988 "Silver Spike" set?  (Both of these locos wore an 8903 road number.)  Thanks.

I'm trying to avoid changing the gear, that's my last resort.  Sometimes that's easy, sometimes it doesn't go so well.

Ted it was for the steam engine first but then it was used in the diesel trucks with internal motor. The parts for the Amtrak Alcos start with 6108903 .

John if you don't find one let me know. I have the gear with 12 teeth that I can press on to my motor for you.

The motors that I checked the silver housing ones had strong magnets. The gold colored housings had weaker magnets . I have both types with the same part numbers.

The key characteristic of the motor is to have no pronounced magnetic detents as you rotate the shaft.  If you rotate a Mabuchi RS-365 drive motor, you'll see what I mean.  You'll feel very little magnetic pull as it rotates.  OTOH, if you rotate some other motors, you'll feel a definite tendency to pull to specific spots at it rotates.  The later type don't work well, if at all, with back-EMF cruise.  Sadly, the later is what is used in this truck I have.

I will test my motor with a back EMF cruise board and see how it works. My motor does not have the magnetic detents.

If it doesn't have the noticeable magnetic detents as it rotates, it'll probably work.  So far I'm two for two with motors that won't work. 

Bruce sent me the truck above (thanks Bruce), but sadly it also has the issue of magnetic detents and the cruise doesn't like it.

The design of that motor is the same and 3 pole.  Are you implying some work and some don't?   G

That's what I'm saying.  I have some of the truck mounted motors that work great with cruise, and others that run very erratic at low speed with the cruise.  Jon Z. explained that the ones that have a strong magnetic cogging effect when you manually rotate them don't give good performance with the back-EMF method used by the ERR cruise products.  My experience with a number of installs has verified that is indeed the case in the ones that I have seen.  I have a K-Line Interurban set that runs great with cruise with the same truck style mounted motors.  However, they exhibit no cogging effect when manually rotated.  This RMT truck uses what appears to be an identical motor, but it exhibits a strong cogging effect and the cruise doesn't work.  Neither motor is marked, so it's hard to say what the difference is.

I just test two trucks with the back-EMF cruise board, one with cogging & one with out. The one with cogging was very jerky and the one without is nice and smooth. I tested them with my Legacy controller .