Case Study: Reverse Engineering CTA Trolley Parts

Moore-Addison is a job shop.  We solicit manufactures to machine non-metallic parts.  We find, as we solicit from company to company, a lot of purchasing people and even engineers who really have no concept of how inclusive the "non-metallic parts" category can be.  For instance, they already buy several phenolic parts from us and it never occurred to them that we work in UHMW or glass based materials as well.  On the other hand, you sometimes find a customer with whom you have been working for twenty-five years or more who knows all too well what you do.  In fact, now they want to expand that category well beyond what you had ever done.

Several years ago, the head of maintenance services at the Chicago Transit Authority [CTA] telephoned and said he had several parts we might be able to do for him.  They were all "old" orphans; there weren't even any drawings; could I look at them?  I went to the trolley repair barn the next day.  We chatted and I eventually asked to see the old parts.  My expectation was to go to the repair area where they lay out such needs.  Instead, Chris pulled out from under his desk a beatup cardboard box with some twenty-three scavenged parts.  They were all well beyond being used again.

But, they were all the CTA had to guide someone in the making of "good-as-new" "OEM" parts.  In several cases they were made of Transite which is no longer used because of its asbestos content.  Even though the asbestos in Transite is "encapsulated", no one wants to be in the same county with any of that notorious material.  There were no part numbers and the OEM was unknown or had gone out of business long ago.  The only thing they had in common was that they were non-metallic.  They were perfect for our business model and the 10 to 25 pieces quantities where not a problem for Moore-Addison although we would have liked to have made them in the hundred quantity bracket.

The biggest problem we had was how to agree and identify exactly a particular part they might want to order.  To mitigate that conundrum, I took digital photos and numbered them from one to twenty-three.  We each have a file we can send back and forth as attachments.  When CTA orders a part, they give us the picture number and their seven digit lot number and we develop the order from there.

Oddly enough, there has been no problem.  Moore-Addison still has the parts to reverse engineer and CTA has pictures of each so we can agree on the one we will produce.  And now we also have many working samples from which we can further hone exterior profiles and/or hole placement and diameter.

The program has worked very well.  An added plus is that we have better access to their shop, made many new friends on the floor.  And we've been able to offer guidance to better materials for all kinds of parts dealing with the 600 amps coming off the third rail.