Preventing roof warpage in PW Alcos?

Roger,

I think that the warping is something that happened not long after they were made. I've never seen one begin warping or get any worse at this stage of the game.

Jim

Well, that's what I want to hear. But I will take some precautions with the bulbs. I usually put an LED headlight in and keep the incandescent for cab lighting. I'll probably use a chip LED for the marker light and number board, but I'm thinking I'll replace the incandescent in these as well.

Roger

Roger:

Be advised that there is only 1 bulb in each unit.  The same bulb lights the headlight, the cab and the number boards.

Bill 

Bill,

Yes, I'm aware. As I mentioned, I generally keep the incandescent for cab illumination, but add LEDs for the other lights. For example, I cut some brass tubing and Goop it in behind the headlight lens. Then I Goop a 5mm LED bulb into the back end of the tube. Creates a torch of a headlight. These Alcos have red marker lights and I want to illuminate them with an LED chip (which will also illuminate the number board). It all compliments the incandescent.

Roger

I heard of the motor heat issue also but that didn't make sense, both the engine and dummy shells have the hump and if it was heat related, the shell would become soft and sag downward instead of upward.

Then I also heard this, that the warping was caused by something in the manufacturing process. The way the plastic was mixed, cooling process, mold release agent that was used, something on that order.

Some of the humps are worse then others. But I don't think they get worse over time!

You're safe, if it hasn't happened by now, it probably won't. The plastic made back then was unstable, and would buckle at the mold sprue. The dish shape in the roof prevented this on later models. But some of the earlier models without the dish shape reinforcement managed not to get this hump. Why I don't know. I have myself have a yellow UP set that are as pristine as the day they left the factory with no sign of a roof hump, like yours.

Very interesting answers......much appreciated. It was worth checking out as we've all seen the results of heat on plastic shells.....from bulbs or smoke units. And it doesn't take very long to happen.  I started using 3M reflective tape a few years ago on the insides of shells above bulbs that I thought might be a bit too close to the plastic. Good stuff.

Roger

Here's a UP set that just showed up on eBay.  This is probably the worst I've seen.

Right Click -----> View Image

for a large view. They're pretty bad.

AMT's F units suffered from the same problem - learning curve using newfangled palstics and getting the temperature correct when molding went on...