Engine size for tiny 4-wheeled 7.5" ga loco?

[WJH]

I keep seeing 350w gear reduction scooter motors on ebay, a 1:1 chain drive ratio off one of these would give me about 5mph top speed (3850 motor rpm, approx 10:1 reduction). Plenty of speed for a 4 wheel switcher, I suspect (I don't need it to "haul the mail"). I hope it's enough torque. A pair of deep cycle batteries would run that for quite a while.

Eyeballing the dimensions of a GE 23 ton boxcab... looks like it might be a relatively easy project. I guess I should order some wheels from somewhere and get started.

5mph is a tad bit slow if you go to any meets, unless you get behind some one who is oblivious that her small American stopping every 50 yards to tend to the fire and cause a huge pile up behind her is NOT OK at a club meet.
As far as torque, I can assure you, 350 watts and that gear ratio will be plenty, enough to do hole shots and snap your neck back if the wheels don't slip, which they will.

[Jawn]

So if that seems a bit slow, the gear reduction unit may be too much reduction... maybe I'd be better off then going with a motor without the gear reduction and just use appropriate sprocket sizes to arrive at the right ratio.

[chooch]

After all the mentions at times of Scooter motors that are already being used in built locos with other gearing sprockets etc. I would wonder why so many "gear reduction" scooter motors would be on E-Bay for sale And at what price. http://electricscooterparts.com/motors24volt.html Maybe compare here for examples.
Further, I have not heard of anyone using Gear reduction motors for rider train units
I have 2/3 scooter motor units with tried and true Non reduction drive systems. That is what I would recommend going with. Thinking outside the box--Nothing wrong with that, it`s good and you never know.
chooch

[6491]

G'day....I have a 750watt gear unit powering my "Little Goose". The only drawback I have found so far is that the gears do get up a whine when pulling hard.
That is from the drivers seat which is directly over the motor. People at trackside say that it is not all that noticeable.
When you add up the cost of extra sprockets, bearings, chains and shaft I don't think there would be a great difference in cost.
As for speed, you can gear up as well as down.

[redneckalbertan]

I keep seeing 350w gear reduction scooter motors on ebay, a 1:1 chain drive ratio off one of these would give me about 5mph top speed (3850 motor rpm, approx 10:1 reduction).

If you want a little more speed and are using a chain and sproket final drive, why not put a slightly smaller sproket on your axle or larger on your gear reducer? An overdrive would bring your speed up and different sized sproket should not impact the price greatly.

You could also use larger wheels to gain in the speed department.

[6491]

That's all I do. I have a couple of different motor sprockets that can be changed in a few minutes. The turnbuckle allows quick chain adjustment.