Since I'm nearing the end phase of my scratch build of the old Cambridge train station (see below),
I'm in search of some advice on my next project -- specifically, my plan is to model the nearby Cambridge Creek bridge:
What I need is a lead on both a source for an appropriate slow speed geared low voltage DC motor (or perhaps two, one for each side, if that's easier to arrange than transferring lift power between the sides), and the bits and pieces to control it (or them).
For control, I'm envisioning a DPDT center-off momentary toggle, wired to reverse the feed polarity depending on which direction the toggle is pushed, and two limit-of-travel normally closed contact switches, one for raised and one for closed (or four, if two motors are used), wired in series with one of the power feeds and positioned to activate when the bridge is in either fully closed or fully open position. The NC contacts of each of the pair of switches would be bridged by diodes (in opposite polarity), so depending on the polarity of the feed (as determined by the DPDT toggle), only one contact switch will be able to interrupt the motor at any given time.
I'm also open to ideas on how to construct the bridge section pivots, and how best to connect the motor(s). Ideally, I'd love to find that there's a pre-built mechanism I can adapt for this project, or something I can kit-bash into a reasonable facsimile. Any suggestions or leads greatly appreciated, and thanks! 
Original Post
