Motor Gearbox Calculator
Posted: Sun Jun 07, 2009 8:42 pm
Posted in the downloads section is an excel file which contains a calculator for determining speeds, gear ratios and motor rpms.
Most of the popular gearboxes are included, if you have the tooth count of any others let me know and I will update the file. This product improves with your input! Enjoy!
The variables in blue are the Electric Motor RPM and Sprocket Diameter. You can of course change the pinion or any of the gears to experiment with different ratios.
Motor Speeds are determined by published specs, measuring shaft RPMs with a tachometer and using math formula.
For instance, our Walker BullDog powered with Graupner Speed400s through a stock gearbox does 2.1mph. That equates to a motor rpm of 16500. The tank weighs about 8lbs. I would imagine a heavier BullDog would turn fewer rpms and conversely a lighter on more rpms. But this gives you a good idea which you can then measure off a distance, get out a stopwatch and do some timed runs.
When we did our timed runs we had the tanks start 20 feet behind the 20 foot testing distance so they were at full speed. Each tank made 3 runs which were averaged to derive at posted figures in green/light blue section.
Most of the popular gearboxes are included, if you have the tooth count of any others let me know and I will update the file. This product improves with your input! Enjoy!
The variables in blue are the Electric Motor RPM and Sprocket Diameter. You can of course change the pinion or any of the gears to experiment with different ratios.
Motor Speeds are determined by published specs, measuring shaft RPMs with a tachometer and using math formula.
For instance, our Walker BullDog powered with Graupner Speed400s through a stock gearbox does 2.1mph. That equates to a motor rpm of 16500. The tank weighs about 8lbs. I would imagine a heavier BullDog would turn fewer rpms and conversely a lighter on more rpms. But this gives you a good idea which you can then measure off a distance, get out a stopwatch and do some timed runs.
When we did our timed runs we had the tanks start 20 feet behind the 20 foot testing distance so they were at full speed. Each tank made 3 runs which were averaged to derive at posted figures in green/light blue section.
It listed about 50 different electric motors for possible use in our tanks from 370-480 sizes.