Saturday, February 27, 2016

Transmission gear choice selection


Gear
827 tire rev/mile

gear ratiogear ratio including differential
Differential
4.24
1st3.7816.03
2nd2.128.99
3rd1.365.77
4th1.034.37
5th0.843.56
Reverse3.615.26 straight cut gears

The Siemens motor we have chosen has more torque capability than the original engine, we will likely need to limit the motor torque commands to prevent transmission failure.

Gear selection thoughts
  • I think I can eliminate reverse due to the straight cut gears.  
  • 1st may be too much fun for teenagers, and not give quite enough speed as we are in the country and 45Mph top may cause traffic issues.
  • 5th, 4th I will find out more as I do the power calculations.  I suspect they will pull too many amps at low speeds, I do not understand the power vs. gear relationship for high speed yet.  Maybe we will need to shift gears before getting on the highway or learn to clutch-less shift? 
  • 2nd gear looks viable for around town use, I have seen postings about limiting the motor rpm to limit the churning in stock transmission that was designed for lower rpm than a common 6000rpm for 45pmh.  Any advice out there on this topic of rpm limits?

Next calculations, Power vs MPH.

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