First Run Con-Cor/Kato PA Question

[spookshow]

Did the screws that hold the lower chassis halves to the upper chassis have some sort of insulating collars to prevent them from contacting the lower chassis and causing a short? I don't have one anymore, so I can't check myself.



Thanks!
-Mark

[central.vermont]

I can answer that once I am home but I'm quite certain thete is.
Jon

[professor_cassidy]

Yes, I had mine apart last week

Shawn

[nkalanaga]

On mine there was a sheet of clear plastic in there, and the pieces were held together with plastic (nylon?) screws on at least one side.

[spookshow]

OK, nylon screws. Got it, thanks.

-Mark

[Doug G.]

Regular metal screws are used on the engineer's side and plastic screws on the fireman's side. (right and left, respectively). There needs to be metal screws on the engineer's side to carry the current from the thin metal bottom plate to the main chassis block since that is ground for the motor.

Doug

[nkalanaga]

Thank you!  It's been probably 40 years since I've looked at one, so I wasn't sure exactly what screw was where.

These were one of the best models in early N scale, but I never did have much luck with them.  That, and the fact that none of the BN's roads owned any, meant that they didn't last long on my roster.  I think they didn't like cat hair, which, oddly, didn't bother the MiniTrix Fs. 

[Doug G.]

On the second version of Con-Cor's PA-1, they DID use plastic collars around the screws that need to be insulated. There is no top plate as on the first version. There are still two split metal halves on the bottom but they are thicker and the one piece block is mounted above with a plastic spacer between the bottom pieces and the block. The motor contacts similarly make contact with the chassis pieces as with the first version.

Noise is reduced by mounting the motor in the top block and the mesh between the motor gears and the cup gears being a bit more precise, not relying on the top plate to exert just the right amount of pressure to keep the parts in the right position.

I have always thought they used plastic collars on the second version, instead of plastic screws, because the plastic screws are easy to break by tightening a bit too much.

Doug

[peteski]

I have always thought they used plastic collars on the second version, instead of plastic screws, because the plastic screws are easy to break by tightening a bit too much.

Doug

That seems like a valid point. Dropping that very hefty metal chassis on the floor would likely also shear those nylon screws.

That later design must have worked well, because they used a similar setup (metal screws with plastic sleeves on one side) on their GP38-2.

[spookshow]

Thanks for the clarification, Doug. What precipitated all this is that I got an email from a guy who bought one and couldn't figure out why there was a dead short whenever he put it on the rails. Turns out that somewhere along the line somebody replaced the nylon screws with metal ones

-Mark

[Doug G.]

Yup, that'll do 'er. You know that sound a power pack makes with a dead short.



Doug