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Since I have installed several can motors in Flyer locos (with flywheels in most). I think they run quite well at slow speeds, much better than the original motors.
However the more likely problem is how you control the motor. Old Flyer transformers were mostly 7-15 volts variable AC output. With a bridge rectifier you get about 5-13 volts DC. Most DC can motors start turning around 2 volts while the old Flyer universal motors were 7-15 volts to match the transformers. So installing a can motor will give a loco that is well past starting (or low speed operation) when the transformer is supplying 5 volts to start.
There are two simple ways to improve low speed control; reduce the starting voltage on your power supply to 2 volts or less, or use a PWM DC motor control connected to a DC power supply of 14 volts or more. Check ebay for dozens of DC motor controller choices. A lot of choices at under $10, postage included. Remember the smoke units draw a lot of power, so your power supply should be rated at 4 amps or more.
Much larger O scale models will crawl with gear ratios of only 15:1, which they could not do if the issues were weight and gear ratios.
On 2018-05-13 14:55, TERRY M STONE wrote:
Oddly, I was involved in a brief discussion twice at the Spree about ideas to make Old American Flyer "crawl" at more prototypical speeds. I have considered the before, but have not been able to do it, even with modern can motors. I'm not sure DCC or other electronic controls are the answer, but perhaps it would be possible with them, though I have my doubts.
I have pretty much decided that the real problem is not voltage control or motors, but gearing and weight. I came to this theory from my background in motorsports and trucking. The American Flyer steam locomotives in particular cannot easily run slowly because most have tall, "passenger engine" drivers, and the motor/axle gearing is too high. As the engine slows, the motor is fed less and less voltage, but at some point "stalls" as it is getting too little voltage to keep the locomotive moving. The 343 and other locos with smaller diameter drivers have a lower top speed, but also would be more able to keep moving slowly, at least to a point.
Picture a semi tractor pulling a heavy trailer. The engine RPM's and the horsepower are nearly constant at low speed and to get the truck moving the driver has to use his lowest gears. If he attempts to move the load starting with the gears used for highway travel, the engine will stall. Actually, the same is true if he wants to move very slowly using a highway ratio gear, the engine "lugs" at too low speed until it stalls. ("Lugging" an engine under load is VERY damaging internally!) And this is what happens to the old American Flyer engines, they stop turning due to too low voltage and high gearing rather than slow down smoothly to a stop.
Remember that it's not only the gears which must be considered. The weight of the locomotive and train (the old Flyer stuff is heavy) and the diameter of the driven wheels must be considered. The diameter of wheels is part of the "final drive" gearing. In auto racing, racers often change gears to suit a particular track and/or track surface. To "fine tune" this gearing for changing track conditions, they often change wheels and tires to those of a larger or smaller diameter because the wheels and tires are the "final drive" between car and track. (Of course tires are also very important to the "handling" as part of the suspension "set up.")
And so, making and ol American Flyer (or most old "Toy" trains) crawl as slowly as a modern "model" locomotive is probably not really possible without serious modification. After all, no one really thought that the same kids who had these toys would still be "playing" with them fifty or more years after they were manufactured! Children "play hard" and so the toys of the old days were made heavy and durable. How many times has that VG rated locomotive been rolled over off a curve, dragging helpless cars behind it?
Perhaps asking the technology of another era to do what modern things can do is asking too much? What do YOU think?
Stumpy Stone in Ohio