Sunday, September 16, 2012

Uncouple Anywhere 01

I did more work on a new version of the traverser (cad and engineering), but such things are boring when compared to wagons that can be uncoupled remotely anyplace on the layout.  The formula is simple, each wagon gets a servo decoder and a servo powered draft gear box to change the position of a coupler.  Temporarily dropping the coupler allows the car to be set out anywhere on the layout--regardless of what it is coupled to.  The evil plan?  Equip darn near every wagon on the road. . . cue evil laughter. . ."muahahahahaha".  Kadee glad hands tremble in fear, "no, not the wire cutter, nooooooooo!"  Seriously, this is one advantage of a small railroad--not too many cars to build in the first place, so each can be a tad more sophisticated.

The video above is of the first prototype: a tad rough, mainly because a wood grain pattern I etched into the floor caused a warp in the thin acrylic.  The pattern is fine in a thicker material, but I needed to downsize. . . I used this model to determine the minimum tolerances, and to experiment with clearances.  The brass was all scavenged from the scrap bin.

Mess of servos. . . small, smaller, smallest!
The workbench is covered with a mess of servos.  There are a couple 6v servos that are downright tiny, but the smallest is a linear 4 volt.  The plan is to assign the largest practical servo to each car type, as you get smaller you loose a little power, and the smallest will require voltage step down via rectifier diodes.  Larger servo's are cheaper to boot.  Servo prices range from as little as a few bucks a piece all the way to twenty smackers, needless to say, evil plans hinge on keeping the twenty smacker servos to a minimum.

Boxcar variant (straight drop), with decoder in background)
I have settled on using Tam Valley Depot's Servo Singlet as the "decoder" for the moment.  It's available in a semi kit form that will make re-configuring it easy.  The bulk of the singlet is in the connectors: if you removed the connectors, and flipped the switches, it can get downright tiny.  Depending on the car, I am planning to equip it with one or two servos, each servo requires a singlet.  In some cases, I am planning on pairing small cars.  Ideally, each singlet address will be the unique car number of the car.  As in the video, the plan is to have a red diode light when the coupler is dropped, so there is a clear indication of a dropped coupler, beyond the coupler itself. 
The straight drop version, cheap servo and a slider without play--very precise.
I have been working with two variants: a straight drop, and a hinged drop.  I like the straight better, even though I started with the hinged.  I figured that I would work both out, and then design the car fleet.  My first designs are based on a frame I had already been building to replace the frame in the ON30 IMA Kits I had.  In the course of trying to re-work the kit, I ended up designing an entirely new car and underframe, and the kits essentially were abandoned (save for the detail parts).  Nothing like building something to figure out what you really want to build. . .

Here is the first prototype, with the previous, non-servo version of the frame.

I'm not the first person to do this of course, there are some folks manufacturing HO box cars with this capability (via solenoid actuated coupler, not a drop coupler as I have it), and there are some European modellers using the Uhlenbrock Digital Servo (do your searches in German).  I think the key to making it fun is the evil part of the plan: enough wagons that you don't have to think about where, when, and how you uncouple. . . you just do it.

The new cut file, arranged to avoid warping!
The first two. . . cut just before the sheep busted out and I had to go fix a fence.

The detail parts arrived fast, thanks to the good service of Valley Model Trains.

1 comment:

  1. Very impressive work. I recall seeing something on these lines from a German manufacturer recently.