Slipping yoke on Kato RDC

[Bill H]

Group,
By yoke I mean the plastic part immediately attached to the motor slipping on the motor shaft.  Has anyone found a lasting cure for this? Short of buying a new motor assembly? I tried CA, it worked for a while, but eventually loosened.

Kind regards,
Bill

changed joke to yoke in title -gfh

[wazzou]

A good two part epoxy like Loctite used in place of the CA should work.  Clean any oil or grease that may be present.

[mecgp7]

Epoxy and you may want to rough up the shaft a little to give it something to grip.

[peteski]

That coupling cracks causing the slippage. I have several of these - seems like a common problem on them (and surprising type of a failure for Kato).

That plastic doesn't take glue well (and I like to over-engineer things anyway). I took a piece of thin-wall brass tubing slightly larger than the small diameter part of the coupling. I then cut teeth on the end of the tube (making a miniature hole saw).  Using that "tool" I created a circular groove in the coupling.  Then I sliced a short piece of the same brass tubing and glued it into the groove (using CA glue).  That makes it a permanent repair since now the cracked plastic part has a brass-reinforced collar.  When the coupling is not installed on the motor shaft, it fits tightly again.

[jcox3751]

Pete,

How about a picture

Thanks

[Bill H]

That coupling cracks causing the slippage. I have several of these - seems like a common problem on them (and surprising type of a failure for KATO)

Pete,
Checking my RDCs all four I have -have both couplings racked, but this is the only one that is slipping on he motor shaft. Indeed a very common problem.

Kind regards,
Bill

[MRLX1020]

Budd sternly warned RDC owners that pulling other equipment with them would void the warranty.   Perhaps Kato should have done the same?

[peteski]

Pete,

How about a picture

Thanks

Yeah, I know, that would be helpful but I didn't take any photos.  Next time I fix one of those I'll take photos.

[brokemoto]

Budd sternly warned RDC owners that pulling other equipment with them would void the warranty.   Perhaps Kato should have done the same?

I recall my reading about this several years back.  I have a number of these and none are showing the problem Y-E-T. 

I have not tried running them with trailer cars.  Usually, I operate them in pairs, which the prototype's builder allowed.

I seem to recall that the M&StL used to use them to pull trailer baggage cars all the time.  M&Stl had problems with them, which Budd repaired a few times as a courtesy, but kept telling M&StL that it would not continue to repair them if it were going to keep pulling baggage cars with them.  Eventually, M&Stl sold them to the C&O.  If the C&O  used them to pull trailer cars, I have never seen a photograph of it.

I did see a photograph that showed a CRI&P RDC's pulling a boat tail observation that had been converted to a passenger/baggage combine.  The baggage end was the observation end.  That would be considered funny by many, in fact, I recall a snide comment in the magazine's caption of the photograph.  You must consider, though, that the only door for passenger access would have been at the opposite end.  Had CRI&P put the baggage section at the other end, there would be no door for passenger access to the observation end.  The photograph was taken in Kansas.

[Point353]

I did see a photograph that showed a CRI&P RDC's pulling a boat tail observation that had been converted to a passenger/baggage combine.  The baggage end was the observation end.  That would be considered funny by many, in fact, I recall a snide comment in the magazine's caption of the photograph.  You must consider, though, that the only door for passenger access would have been at the opposite end.  Had CRI&P put the baggage section at the other end, there would be no door for passenger access to the observation end.  The photograph was taken in Kansas.

Or, you could run the RDC as the observation car:
http://bcoolidge.com/Amtrak_71-75_Boston_Pix/%27The%20Night%20Owl%27%20with%20RDC%2072%20Back%20Bay%20Station%2010_72Edited.jpg

[davefoxx]

Or, you could run the RDC as the observation car:
http://bcoolidge.com/Amtrak_71-75_Boston_Pix/%27The%20Night%20Owl%27%20with%20RDC%2072%20Back%20Bay%20Station%2010_72Edited.jpg

Push-pull?

[narrowminded]

Does anybody have a picture of what this "yoke" looks like?  Sounds like more than a few of these are around with this problem.  Maybe time for a new one that stays together.

[peteski]

EDIT:  I was going from memory and I didn't remember correctly.
I just take a quick peek at the RDC universal coupling (yoke) and it is different that the one if the photo below.  The RDC driveshaft has a smaller diameter ball on its end and the coupling also allows the shaft to move in and out of the coupling.  So the part shown below is not a good substitute. Similar, but different. 

It is the sea-foam green colored part. They are still available from Kato, as a part of the worm assembly - they don't sell those separately.

[ Guests cannot view attachments ]

[narrowminded]

It is the sea-foam green colored part. They are still available from Kato, as a part of the worm assembly - they don't sell those separately.

(Attachment Link)

Are both ends hex drives or is the assembled end a cross yoke type?

[peteski]

Are both ends hex drives or is the assembled end a cross yoke type?

Cross-yoke type. The assembly in that photo is not for the RDC - I only used it to show the yoke part.  I don't have the model handy but IIRC, both the worm and the motor ends have the greenish yoke and the (much longer) drive shaft doesn't have a hex-end.  But it is not the shaft that is the problem - it is the greenish part - it splits on the metal shaft side.

This would take a bit more time consuming to machine than the washers/grommets you have made in the past. Especially in larger quantities. I'm sure you realize that the Kato part is injection-molded.