Motor Selection

[Espeefan]

25 RPM sounds like it's in the right ball park for speed and power. What you need to do is figure out your tire diameter, and then run the math to figure out it's actual MPH, at full speed, or the feet per second of travel. Just figure out your tire diameter, figure out the circumferance, and multiply the distance traveled per hub or gearhead motor revolution. That will let you know how fast the model will be.

[Heavy Metal]

I did the math again and motors I selected would do 27' per minute (.45 FPS or .31 MPH) assuming my target tire diameter of 4.14". That's pretty darn slow for moving from one job to next! I obviously selected these motors for the power.

If I stick with these I definitely need to think about way to adjust ratio. I can't mount them directly to the axle anyway because I miscalculated available space for two motors back to back...the model would need to be 1:12 for both motors to fit between the rims like that (and since I want to haul it w/ 1:14 truck...I'm sticking w/ 1:14)! So offset mount w/ spur gears driving axles would be my thought...then could change gears later if I want to go up or down.

Joe