Little Help with JVN and HAB3

Guys, I need a bit of backup on my thoughts. We have a climbing method that requires us to power a single axle (the other axle passively rolls). JVN assumes that every gearbox is used in pairs which is not the case here. I have used the single speed custom tab and to compensate for the single gearbox, I have doubled the robot weight from 155# max to 310# max. I left the drive eff at 81% and the gearbox at 80% just to be super conservative.

Can I trust the output of this is realistic? This is a major part of our design and we are going to be hard pressed to finish it by bag day so I want to make sure all my calcs are right.

huh, I’ve never used the spreadsheet, I just gather some students around, and we do the math using best guesses, and making some rough notes. It generally seems to work that way.

Maybe you could see if you can figure out how to do the math without the spreadsheet, as a check on your work?

or perhaps you could give enough information about the system, that some of us could check your results. A crude sketch of the loading on the gearbox or the configuration of the mechanism, and the planned gear reduction and what motor you plan to use, should be enough to go on.


Custom 1 speed tab lets you choose how many gearboxes.


I see where you getting this. I was confused by

“The drivetrain calculator assumes two identical gearboxes per robot, each driving one side of a skid steer style system.”

But both the Custom 2-Speed tab and the Custom 1-Speed tab give you the option for number of gearboxes!


You may also use the “rotary mechanism” tab.

^^ what @philso o said. Treat this as an arm that lifts the robot’s weight.