Pesky Model Power 4-6-2 Cover Plate Wires

[mmagliaro]

In the process of fixing one of these up for someone, I hit upon a good way to solve the problem of the annoying Model Power cover plate, it's mangled wiper strips, and those darn wires that notoriously break off when you remove the plate.

The idea is install two little phosphor bronze rectangular contact pads, soldered to the stubs of the wires that stick out through the bottom of the frame (where they usually break off).   Then, do a little bending and add a bronze spring to the contact strip in the cover plate.  After that, the cover plate can be removed at will, with no wires attached to it!

Also, after this mod, since there are no wires in the way, I found it very easy to get the plate off an on, and slip those wheel wipers right in behind the wheels as I would re-install it, with no hassle.

This did take some delicate soldering, but it's not too awful.  A few hours' work.

To begin:




Now, the contacts inside the cover plate itself:


So now, when you put the cover back on, the little spring touches one of our new frame pads, and the bent part of the strip contacts the other, completing the circuit.  Everything is springy phosphor bronze, and none of these are moving parts, so the contact is quite reliable.

Other "by the way" things about the MP 4-6-2:

If you add a traction tire driver, here's something to be wary of:





Last, but not least... if your MP engine has drivers slipping all over the place on their axles, causing rod jams,
you will find that you can hold a driver on one side by pressing your thumb down on it, and you can then rotate the driver on the other side back into the correct position just by pressing on it and nudging it with a finger or thumb.

Once you get them all lined up on one side, as darn close as you can by eye, thoroughly clean the axle tips with a brush, alcohol and some paper toweling to get rid of all the moisture and oil.  Then apply a drop of Loctite to each end,
with the engine lying on its side, so the Loctite gets down into the axle hole.  I strongly recommend using
the "green" variety of Loctite because it is design to draw into joints like this via capillary action, unlike the blue or red varieties that really need to be applied to the parts before they are put together.

Once the LocTite is hard on one side, run the engine on its back at low speed and scrutinize for any binding.  If you have a little, fix it by rotating a driver or two on the OTHER side.  Then clean and Loctite that side.

AS it turns out, since all the drivers are geared and the rod holes are egg-shaped to allow for a little error, it is quite easy to fix quartering problems on this engine.  Loctite is the key.

[u18b]

Max,

I think the Model Power Pacific is a wonderful locomotive- as long as you don't have to take it apart.

Thanks for this.

[nkalanaga]

Didn't a recent post say that MRC bought Model Power?  If so, as easy as this fix seems, maybe they can make it at the factory.

[peteski]

Didn't a recent post say that MRC bought Model Power?  If so, as easy as this fix seems, maybe they can make it at the factory.

Nice solution Max!

Nkalanga, adding this mod would increase the labor cost and parts count. Unlikely to happen.  Back in the Model Power days many modelers suggested changing their tender pickup scheme (from high-friction axle wipers to the Kato-like axle-end pickup)  -  that never happened either.

[mmagliaro]

Nice solution Max!

Nkalanga, adding this mod would increase the labor cost and parts count. Unlikely to happen.  Back in the Model Power days many modelers suggested changing their tender pickup scheme (from high-friction axle wipers to the Kato-like axle-end pickup)  -  that never happened either.

I agree, Peteski.  Making this a factory mod would require reworking the cover plate and probably making
a couple of little inserts for my little pickup pads that I soldered in.  I can't imagine them doing that.

I'd be happy if they would just ditch those stupid tender trucks.

-- Max

[nkalanaga]

Peteski and Max:  You're probably right.  I was thinking about the quality of the locos MDC imported back in the 70s, in their first brief entry into N scale, and hoped that they might be willing to upgrade the MP models.  But it would raise the cost, and thus the price.

[Lemosteam]

Max, is this design concept common top all MP locos?  Just Curious as I will be kitbashing one this fall.

[mmagliaro]

Max, is this design concept common top all MP locos?  Just Curious as I will be kitbashing one this fall.

I believe so.  I have had the 4-6-2 and 4-4-0 apart, and they are both wired this way (and they both have this
hideous cover plate/wiring/pickup wiper system).   Oh, and the 2-6-0 does too; I have one of those.

I don't have a 2-8-2, but I would assume it's the same.

=====================
One thing you will find is that after you have taken that plate off, straightened out the wipers once and for all,
and then done a little heat melting or super-glueing to tack them in position, they will no longer be such a chore
to put back in without bending them all up.  The trick is to start from the front driver.   Tip the cover plate
so the front end is pointing down into the engine (with the engine on its back).

Put the front edge of the cover in, tucking the wipers behind the front drivers with a toothpick, Xacto, or similar tool.
Get the front edge completely down, and think about this, now, as pivoting the cover plate downward.

Now, lower the back edge a little until the next driver's wipers get close, and tuck them behind the center drivers.
Continue pivoting the cover down, and do the last driver.

The wipers naturally sweep right in behind the wheels with no fuss. 

When the wipers are only held in by the plastic retainer, they flop around so much that it is hard to do this.  But once they
are heat-melted in place so they don't flop around, the whole thing goes right in.

[Lemosteam]

Got it!  Thanks Max!

[mmagliaro]

Just to close the book on this.

Unfortunately, after all this work, on this particular engine I could not stop the drivers from slipping out of quarter.
No Loctite, JB, ACC or anything else would hold them.   I even drilled holes horizontally into the wheel hubs and glued
brass pins in there, and even cut small slits into the inside of the wheel holes, hoping that with LocTite or JB in there,
it would fill into the slits and hold the wheel even it the stuff can't stick to the Delrin.

Sigh.  So the electrical wipers work perfectly.  But the engine's a basket case because of the slipping drivers.

I've always had great success dripping green Loctite right onto the outside of the axles, so it would wick into the joint between axle and wheel,
and it has always held really well.  But not this time.  Ah well.

There are many other extremely involved and exotic measures I would take if this were my engine, but it's not.  It's for someone else.
And it's not practical for someone to invest all that money into all those hours for me to go that far.  So we've agreed to just
consider this one a lost cause.

I wanted to add this note as a caution to anyone else messing with these.  The MP wheels are fragile and they do commonly
slip on their axles.  And sometimes... you may not be able to fix them very easily, if at all.

[victor miranda]

I ummm ah er have noticed.

the casting cracks and it has little that can keep it straight.
nothing that can hold the axle.

when I looked at it, I decided the fix was going to be installing
a new center made of metal like brass.
that was to be glued in place with epoxy and then the axle can be installed.
That is a lot of work when compared to buying parts.

I mostly wish Kato had decided on a Pacific type years ago.

victor