Working on Servos - on the Barr Yard staging (Lower Level)

Barr Yard -- on the B&OCT prototype is a major classification yard on Chicago's south side. Interestingly, it was a flat yard. B&O long-distance freight trains originated at Robey Yard -- a modest yard on Chicago's Near West Side. Almost all eastbound B&O freight trains stopped at Barr to drop off inbound cars. The exception was the New York Trailer Jet (NYTJ)-- a priority train that carried piggyback and reefer traffic. The NYTJ picked up reefer traffic at Robey and piggyback flats at Forest Hill -- a piggyback yard immediately south of 75th St. Tower. On the inbound side -- every freight stopped at Barr except the Chicagoan and Chicago Trailer Jet. 

The 75th St. Tower is the end of the modeled portion of the B&OCT in N Scale, anything railroad east of that point is represented by staging -- called Barr Yard. A more detailed discussion of the prototype will be the topic of a future post or two.

This much introduction was needed to give context to today's post -- which is about installing the servos which will control the routing of trains in and out of Barr staging. 

This project required outside help, provided by Steven Cox. Thanks Steven.

In addition to helping with the track plan design, he volunteered to write the software that drives the servos. There may have been an expectation that I would learn how to write code to operate an arduino nano. That never happened -- the job quickly exceeded my rudimentary grasp of the concepts of computer programming. I took one class in computer programming (Fortran) in the early 1980s when I was at the University of Maryland. At that time, the coding was put on to punch cards and passed over the counter to the students working at the computer center. My takeaway was learning how to operate a key-punch machine. That was a memory best forgotten.

I spent many Zoom meeting hours helping (watching) Steven develop the code. The software is ready for a real world test. 

And now things have moved into a realm where I'm much more comfortable -- setting up the hardware. For the past two weeks, I have been installing servo holders and servos at the exit to Barr staging.

Servos installed at Barr exit 

At the turnback end -- entrance to the staging -- the servos are already in. But, the servos need to be connected to the track.

Those connectors are mostly fabricated from paper clips 

and some servos need to be re-positioned because the holders are either too close to or too far from the track. 

screwing in a re-positioned servo holder

The two photos above show the servos, a wiring bridge and servo connections to a PCA-9685, which distributes commands to the motors. Next up -- testing the routes. So far, I've found a couple of servos are throwing backward and one servo is not responding at all. All these issues will be tracked down -- and will have to be documented. 

It will take a session or two with Steven to de-bug. The layout will have four staging yards that will use this prototype to control train routing.