Rivarossi Berkshire Ressurection

[peteski]

Thanks!   Slowly I'm progressing.  My plan is to get the drive train working on DC first, then add the valve gear, then do the DCC conversion.

Sounds  logical. 

[nickelplate759]

Sagami is in place (just with tape for now).   Now I need to tune things.  There's a slight bind once per driver revolution, so I'm guessing I don't have all the drivers aligned just right  .

Gotta fix that before the next step.

-- Update - much improved, but not perfect. I've come to suspect that it's the best I can do without tightening up the axle bearing slots (there's a fair amount of play in the axles) and making sure the drivers are identically aligned on their gears.  Knocking off for tonight.

-- Query - I'd like some recommendations on what DCC decoder to consider.   

1. Since pickup is old-fashioned (one side of the tender, one side of the drivers is all you get), I think some kind of keep-alive is all but mandatory.  I don't want to make my own (yes, I know it's simple, but I want to put my time into something else).  I'd prefer one that was easy to install to the decoder without having to unwrap the decoder first.
It doesn't need to be big enough to run the engine for more than a second or so.

2. I want at least three functions (forward light, reverse light, Mars light - I'm going to try and fit it in!).

3. The decoder and keep-alive need to fit in the tender.  At least the tender isn't tiny.

4.  I'd rather not use Digitrax for this engine.   I've got a mix of Digitrax and TCS decoders, and I think I like the TCS Mars light better.

5.  I'm on the fence about putting sound in it.  If I do, it all needs to fit in the tender, and I don't want to have to load sound projects as (I think) that requires special equipment that I don't want to acquire.   I'd want to identify a sound decoder that can at least approximate an NKP Berkshire better than the Bachmann 2-8-4 does before I'd even consider it.

EDIT -
I settled on a TCS M4-KA decoder with a KA4 Keep Alive.  No sound.
Now the project goes back on ice until the DCC parts arrive. 
I'll need to plan where the wires will run - I need 6 wires between the engine to the tender ( 3 for the lights, 2 for the motor, 1 for power from the drivers).

[peteski]

Sagami is in place (just with tape for now).   Now I need to tune things.  There's a slight bind once per driver revolution, so I'm guessing I don't have all the drivers aligned just right  .

Gotta fix that before the next step.

-- Update - much improved, but not perfect. I've come to suspect that it's the best I can do without tightening up the axle bearing slots (there's a fair amount of play in the axles) and making sure the drivers are identically aligned on their gears.  Knocking off for tonight.

Wait, if there is a hitch with no siderods attached then the driver alignment is not the problem - Their gears will simply mesh with the idler gears.

EDIT:  You mean that the drive axles have sloppy fit in their bearings?  That coudl cause binds, but I'm surprised it is tied a full revolution of the drivers.

[nickelplate759]

Sorry, I was unclear.  The side rods are in place, but the valve gear is not.        After adjustment (for the 42nd time at least) of relative driver rotation the hitch is pretty much gone, but slow speed is uneven at best, and the axles have a lot of play in them.  I don't think the drivers were ever perfectly quartered or aligned with their gears, but they are close.   At this point I think I have it running about as well as can be expected without reworking the driver bearings and quartering, which I'm not planning to do.

I've also decided not to put sound in this - I'll save that effort and $$ for upgrading some better-running models (like my LifeLike Berkshires).
So, just a decoder and keep-alive, which should be easy to fit in the tender.

[u18b]

I'm sure you have already done this..... but be sure and check for cracks in the gears on the drivers.
They are pretty notorious for cracking.

[nickelplate759]

I'm sure you have already done this..... but be sure and check for cracks in the gears on the drivers.
They are pretty notorious for cracking.

Thanks for the suggestion, but yes I checked and they are fine.  I have way too much experience with cracked gears.

[peteski]

I'm sure you have already done this..... but be sure and check for cracks in the gears on the drivers.
They are pretty notorious for cracking.

Con-Cor Rivarossi Berkshires have all brass gears (at least all the ones I ever dealt with did). Those don't really crack (often). 

[Doug G.]

Con-Cor Rivarossi Berkshires have all brass gears (at least all the ones I ever dealt with did). Those don't really crack (often). 

They just get kind of ugly as they age.



Doug

[nickelplate759]

I'm making slow progress.  The new Sagami motor is in.  I put the valve gear back, but I'm not certain I got it right.
I removed the valve gear by undoing the screw on the main driver crankpin.  I tried to keep everything in order as I did that, but...

Afterwards I found one tiny washer on my workbench that I didn't remember coming from the valve gear.  Just one.  My hunch is that it actually came from some other project and I just happened to notice it. It seems to work, in any case.

Here's the order in which I reassembled things (both sides of the engine):

             Driver : Thin Washer: Side Rod : Thick Washer : Main Rod : Eccentric : Screw


I'm quite certain that the Driver and Screw are in the right place 
The "Thick Washer" is more of a short tube.   Should there be any other washers in there?


Also - a different problem. I think I found the source of a slight bind in the drive train - the left side main driver isn't square on its axle, so it wobbles a bit.  All the other 7 drivers are fine.    I probably should have checked that before I got this far.  What's a good way to fix it?

[Doug G.]

Try squeezing where the two drivers are farthest apart.

Doug

[nickelplate759]

Try squeezing where the two drivers are farthest apart.

Doug

Wouldn't that be just as likely to mess up the good driver?   

I was thinking of putting the axle+drivers assembly in a vise and squeezing just enough, but I've no experience doing this.   My main concern is that if I try and straighten the driver it will end up loose on the axle.  If it's not too loose I could use Loctite after I get it straight and in gauge, but if it is I'm at a loss as to how to compensate.

[peteski]

If the wobble is not too severe, I would leave it alone.  The 40+ year old plastic spokes is not something I would but much stress on. It was probably like that since the loco was manufactured.

[mmagliaro]

Well, there is really no "easy" way to fix this.  Like Peteski suggested, you may have to make a judgement call as to whether it is worth fixing.   

You can try gently squeezing at the "wide" spot, (try not to pry on opposite driver, but instead, see if you can brace your tweezers or fine pliers on the frame somewhere, so - as was suggested - you don't risk messing up the opposite driver)

You can probably fuss with it - push in the wide spot, roll it some more, see another wide spot, push that in, and so on, until it gets "better", but probably not perfect.  And the put some Loctite into the end hole and pray.

I have also tried fixing problems like this with a machined metal block that you can put between the drivers.  It has to be machined to be just the right width so that when they are both pressed in hard up against it, they are in gauge.   You can squeeze them against the block.

But even then, it's a crap shoot as to whether the Loctite will hold on plastic firmly enough to keep the wheel from going back to its wobbly state again.  Once these things have gone out of whack, it's hard to ever get them true again.

Editorial: This is why I strongly discourage people from correcting wheel guage by just prying behind the wheel with a screwdriver.  That's a good way to make the wheel wobble on the axle and then there's almost no fixing it.

Your other alternative is to scour eBay and swap meets for a dead Berk and swap in a donor driver set.

[nickelplate759]

Well, there is really no "easy" way to fix this.  Like Peteski suggested, you may have to make a judgement call as to whether it is worth fixing.   

You can try gently squeezing at the "wide" spot, (try not to pry on opposite driver, but instead, see if you can brace your tweezers or fine pliers on the frame somewhere, so - as was suggested - you don't risk messing up the opposite driver)

You can probably fuss with it - push in the wide spot, roll it some more, see another wide spot, push that in, and so on, until it gets "better", but probably not perfect.  And the put some Loctite into the end hole and pray.

I have also tried fixing problems like this with a machined metal block that you can put between the drivers.  It has to be machined to be just the right width so that when they are both pressed in hard up against it, they are in gauge.   You can squeeze them against the block.

But even then, it's a crap shoot as to whether the Loctite will hold on plastic firmly enough to keep the wheel from going back to its wobbly state again.  Once these things have gone out of whack, it's hard to ever get them true again.

Editorial: This is why I strongly discourage people from correcting wheel guage by just prying behind the wheel with a screwdriver.  That's a good way to make the wheel wobble on the axle and then there's almost no fixing it.

Your other alternative is to scour eBay and swap meets for a dead Berk and swap in a donor driver set.

Thanks Max.  I have a plan, based on your advice.

Phase 1 : Try running the model with the wobbly driver (and yes, it's clear that it's been this way a long time).  If it doesn't derail, leave well enough alone.  the hitch is relatively minor.

Phase 2 : ?

Phase 3 : Big Profit No, I mean replace the driver pair.  It turns out I do have a spare driver set from a dead Berk.  I'd have to turn the flanges and remove the odd red grease they are covered in (I got them that way - but they were cheap).

[mmagliaro]

I'd say that if I can actually see the wobble as it runs down the track, it would bother me enough to fix it.  But if you can only see it when it's flipped on its back running in a cradle, I'd leave it alone.    And I'd vote for the replacement driver set.  Just make sure you test that replacement driver set first, in the engine, to make sure it doesn't have any wobble, before you bother turning down the flanges.