06/10/01 rev 01/16/07
Our son Randy, the one raising our four perfect granddaughters, lives about 240 miles West, three hours via I-84. Being properly raised to love model railroading, he put the family to work building a most attractive garden railroad for his Dad to play on. They terraced the back yard that sloped up away from the house. He built a lake and stream with waterfalls while my lovely daughter-inlaw Coleen planted lots of pretty stuff, Randy and the youngest daughter then laid track for a logging railroad, calling it the Sawtooth Meadows line, SML, just a SMalL railroad
Click here for 54k birdseye view
Shay Locomotive, SML #5, a G-guage, 20.3/1 scale
Now the SML is very successful in building and marketing skills, but they needed to look elsewhere for the some specialized engineering skills and that's how the alliance between the the SML and the Teton Short Line, TSL, was forged. Oh yes, we admit there is some nepotism involved too. Our TSL civil engineering department was able to assist in trestle construction, but the real challenge came when the SML asked us to bring the 1920's Shay into the twenty-first century to support a modern logging operation. We do this for environmental concern. No diesel, or developed roads. Just like a hundred years ago, we burn wood, a renewable fuel and take up our tracks when we leave. Careful harvesting of mature trees and using the slash for firewood reduces the risk of future fires and leaves the woods better than we found them. Research and Development started with the TSL Shay #2 that has trackage rights on the SML. When we had developed a reasonably successful prototype, the SML #5 Shay was updated. Our Shays use computer technology like the modern diesels on the prototype. If Mr Shay and Lima Locomotive were still around, they might be able to market this fine machine again.
The challenge presented to our TSL Engineering Dept:
- Radio Control with no antennae showing.
- Synchronized Sierra Sound
- Uninterruptible Battery Power
- Track power to float charge the battery
- Extra remote functions.
- No battery cars
- High reliability with minimal maintenance
- Nothing showing to hint at the mods
We searched the Internet for ideas. Got lots of information and good hints to repair weaknesses in the Bachmann Shay from George Schreyers Large Scale Trains Page . George has a wealth of information for you to sort through. Buried in it all you'll find the tips for Shay stuff that we used for this project. First, you get the Hillside kit to improve the power contacts, then fix or replace the wheel bushings per Georges tips if necessary. All of ours had failed and you can see the extra brass washer in the pix below. They were repaired by adding the washer and serving the fractured bushing between the washer and wheel with carpet thread buried in epoxy. This totally captures the broken pieces.
I found many problems in the trucks, most related to the quality of plastic and/or excessive force in assembly. I believe the assembler used one of those air wrenches like they do at the automobile tire shop and fractured most of the connections. It took a lot of epoxy, plastic and wire ties to repair it all. Especially difficult to repair were the destroyed screw anchors atop the trucks. Most of them were split and two were ripped off. This pix, sans the brake beam assembly, gives you an idea of what I finally done. The 1/4" angle brass structure sits atop the failed plastic piece and takes 4-40 bolts instead of the "plastic splitters". The "nuts" are made from 1/4" brazing rod and soldered to the the angle stock. The white styrene block beefs up the flimsy cast-on tab on the side. It welds nicely with MEK.
Finally, in the two locos we've found two of the eight spur drive gears on the axles split and slipping on the axle. in two. A third one had split completly in two and dropped off. Easy to spot, the axle turns freely. Remove the gear, clean it, make a pair of tight coils of music wire, or cut a coil from a spring and press into the recess on both sides, then fill with epoxy. Carefully press it back on.
NO- they have not been abused, but they are "first generation" and I assume the Bachmann learned a lot in the first go-around.
06/25/01 Update- We visited the SML this weekend and found that Randy had contacted Bachmann. They sent new plastic truck parts i.e the gear case, bottom and top. They were drilled or molded with larger screw holes that would be less likely to split out. The plastic has a slightly differant appearance and did not fracture when assembled.
Here you see the Engineers (me) approach- fix it & make it better- and the Marketing Exec (son, Randy) approach- give the vendor a chance to make it right. Thank you Bachmann for your response.
With the mechanical problems laid to rest, we proceed with the original challenge, so back to the drawing board and lab.
Initial tests were made in May 2001. Improvements are continuing but the tests were remarkably successful, running both Shays on track covered with all the debris of Winter, leaves, bird doo doo etc. We even went beyond the end of track into the mud with whistle tooting and all the wonderful sound that Sierra records into their gadgets.
04/05/03 update. The mechanical problems came back, this time resulting in complete failure because Bachmann advised us that they had no parts to sell us or to fix the thirty locos in their shop. Spring was coming and there is work to be done in the woods. Click here to see what we did
UNDER THE HOOD,
or in this case the tender shell. The firewood load has been lifted off to reveal the speaker and antenna connection. Nothing except plug-in connections for the tender light, speaker and antenna is attached to the shell. That virtually eliminates the problem of wire breakage. You can see how the speaker opening is protected by a 1/4 inch high dam to reduce risk of water entry. A scrap of Saran wrap over the speaker and our only concern is flood over the running boards. On the far side and rear sideboard is the (not painted yet) antenna foil.
We smoothed the floor flat, filing off the pre-cast speaker mounts and then fabricated a removable dummy floor of .060 Styrene to build upon. In the tender goes the battery, Sierra sound, 418 mHz receiver/decoder and the PIC microcontroller. None of the devices generate significant heat. the speaker is in the top where it's sound can travel thru a porous wood or coal load. The 12 volt, 1.2 amp-hour lead-acid battery nicely replaced the weight of the slug that had to go.
The heat generating components go underneath between the frame rails, the same place that Sierra suggests putting their six volt battery for the sound system. We don't use their battery so that space is available. It's well ventilated and the heat sinks attach to the metal frame rails. These components include voltage regulators, motor drivers, rectifiers and solder terminals made from strips of PC board. The picture shows one of the two heat sinks with the voltage regulators. At the moment, I have the other one with the motor drivers removed. Notice the additional contacts at the bolster for the motors that have to be separated from the track- again see Georges site for the details. At the lower left is the connection for the tender light that makes when the shell is dropped on. Above is the charging jack and on/off switch.
When you flip it over, the only thing visible is the switch and charging jack. Paint 'em dull black and they go away.
No further use is made of the firebox or boiler space.
VOLTAGE REGULATORS GALORE!
Bachmann equips the Shay with a LM317 VR programmed for 9 volts for the lights ssand fire simulating flicker board.
Sierra equips their sound system with two VRs, one for internal 5 volts and one to charge their six volt battery from the track. We don't use their battery.
Track power is from a regulated source of 17VDC, the amperage capacity can be whatever is needed for multiple locos. We chose this voltage to minimize the heat generated in the on-board regulator that floats the battery at 13.8 volts. This allows us enough overhead for the on-board 3-amp Schottky diode bridge and the low overhead LM2941 regulator. Using DC rather than AC eliminates the need for a bulky filter capacitor on board that would be essential for long battery life.
Sierra system power is derived from the 13.8 volts with a LM317 voltage regulator programmed for about 7 volts.
PIC microcontroller and the radio receiver take 5 volts from a LM78L05 voltage regulator.
The smoke generator has been replaced with a 5 Volt LGB device. A programmable LM317 located below the stack is used.
Radio is 418 mHz with Holtek 12 bit coder/decoders. The PIC is MicroChips 16F84. An octal buffer, 74LS240, isolates and protects it from the external circuits. Variable features like acceleration rate, brake rate, start voltage and others is easily programmed in-circuit with a laptop computer. Just lift the tender shell and plug in.
- Original wiring was greatly changed. Separated the motor and track wiring using the techniques on George Schreyers site. The new wiring was terminated on solder terminal strips fabricated from PC board strips and epoxied under the floor behind the firebox.
- FLICKER BOARD- The schematic and a pix of Bachmanns circuitry is on George Schreyers site. I kept the flicker circuits intact and used the 9 volts for the cab light only. Its gets its raw power from the track so the cab light is an excellent indicator of track condition. It's nice to know this to prevent running the battery down when parked. There is a resistor to be clipped to keep it working. The firebox flicker lights work whenever track voltage is available, regardless of speed. They're cute- never could run fast enough to see them before.
- BATTERY- Primary power supply is 13.8 VDC derived from a lead-acid battery in a float charge mode drawing power from the track. A charging jack is available for off-track charging. We could run on plastic track for about 45 minutes. Great for show & tell :-)
- HEAD & TENDER LIGHTS use the 13.8 VDC power with 75 ohms in series with each for surge limiting and long life. They are direction controlled with the PIC microcontroller. I also experimenting with white LEDs which need about 1000 ohms for a very bright bluish light. I tried tinting them with yellow glass stain and ended up with ugly green light. While the LED it will throw a nice beam at night, when looking into it, it's a tiny light spot in the center of a big lamp fixture- Very unrealistic. I'll put an incandescent bulb back with a milky or frosted glass so the whole thing has a glow to it. We're open for ideas here.
- SIERRA SOUND system is used without modification. The radio link has the capability of adjusting sound volume and reprogramming all the options that Sierra offers and that's quite a lot. If you replace one of the retainer boards on the coal bunker with a piece of clear or milky plastic, you can get a peek at the red & green LEDs on the sound card that you need to see when programming it.
- SOUND SYSTEM SHUTDOWN was frustrating. Sierras system shuts down after a couple minutes to conserve battery. We could remotely restore it by issuing a brief volume up or down command, but the discontinuity is rather disconcerting. The dynamo shuts down after 32 seconds of no motor voltage so to avoid unrealistic cycling of it, you need to stimulate the sound system at least every 30 seconds. Sierra suggests leaving the throttle slightly on to keep things alive, but in a pulse width system like this, the engine will crawl away at the slowest possible setting. Putting a fixed voltage on it kills the blowdown sound that occurs when the speed reaches zero, so that wouldn't do. My solution was to very briefly kick the motor forward, then backward every thirty seconds. There is no perceptible motion. This is easily done in the PIC programming.
- RADIO/MICRO BOARD is custom built on perf' board and is physically about the same size as the Sierra system. Like the Sierra unit, it slides into slots in the support structure built up with .060" styrene. A ten pin .010" spaced header connection makes it easily removable. The antenna is made from a six inch strip of 3/8" wide foil cemented atop and to the tender wall also with a plug-in connection.. Optionally, an inconspicuous quarter wave vertical antenna, about 6 inches, can be plugged in for mazimum range. Eight remote functions are available and I assigned them as:
- Emergency Brake
- Sound Volume Down/program
- Sound Volume UP/program
POWER AMPLIFIERS or more properly, motor bridge drivers, are needed for the husky G-guage motors. The stalled resistance is very low for a potential of up the 5 or 6 amps current flow if stalled. They won't stall on the Shay- they just slip, and the high current is only seen during the short drive pulse when the motors are starting. (Unless a spur gear breaks and they jam, blowing the power amp) Our tests with the Allegro 2998 have been satisfactory, but it does need overcurrent protection. SMOKE GENERATOR- Removed the original Bachmann smoke unit and replaced it with a 5 volt LGB type installed in the balloon stack with thermal insulation. A LM317 programmable voltage regulator is mounted in the former smoke unit area. The microcontroller holds the voltage at about 3.6 volts, keeping the smoke fluid just below the active temperature. When the loco is accelerated, the voltage jumps to 5.5 volts and smoke is very active. The programming allows you to bump the THROTTLE a notch to activate the smoker without moving the engine. A strategic pause, and the next bump can be made to coincide with the first smoke puff. Very nice effect. After 30 seconds of no throttle change activity or immediately if BRAKES are applied, the smoker cuts back to conserve the fluid and life of the device.
The wiring diagram for our 21st Century Shay shows the detailed component interconnections and to some extent their relative physical placement. Megenta color outlines circuit boards, solder strips and pads made from printed circuit board material.
The perfboard holding the Radio receiever/decoder, 16F84 PIC and buffer/driver chip is expanded below. It's the same width as the Sierra Sound card and mounts behind it in the tender. The notch in the top is where the overhead speaker magnet fits. A ten pin connector at the bottom makes it easily servicable and the five pin connectro at the top left provides for easy in-circuit programming. I use PICBASIC by MEI for easy programming. I'm not into computers- I just like what they can do for my model railroading hobby.
03/30/02 Murphy paid us a visit and as usual, did it in direct proportion to the number of visitors. While showing off for the PNR Third Division Meet in Boise, we managed to blow the power amps in both locos. You really need the overcurrent protection! A better power amp is in the works using hexfets with a marvelous little driver chip and it seems to be indestructible. I'll get the details posted soon.
04/23/03 Sorry about taking so long to get this posted, but we did come up with a very successful motor driver last summer. I discovered a MOSFET driver chip, LTC1155 by Linear Technologies. Along with a quad of husky IRFZ44N power MOSFETs, we have our motor driver complete with current limiting. Today, as I read of another motor driver I was reminded that I hadn't posted our earlier solution. Take a look at the Motorola MC33887DH Integrated H-Bridge as described by Lonne Mays in Circuit Cellar April 2003.
I do hope that I've stimulated your thinking about merging steam and computer technology.
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