Gear boxes

[Fluffaluffagus]

Does any one know of good substitutes to the Versa Planetary gearbox? Suggestions and links would be appreciated.


Thanks.

[Joe Johnson]

What are you unhappy about the the Versa Planetary? If we don't know what problem you are trying to solve, we can't suggest solutions that will work.

Dr. Joe J.

P.S. Full disclosure: I am a huge huge fan of Vex's VP. They are have been a game changer in FIRST FRC robot design (imho).

[Fluffaluffagus]

For us the Versa Planetary gear boxes are too big and at this time in build season the whole idea of rearrangeing our robot does not look like a good idea.

P.S. we blew our other gearbox doing tests.

[cad321]

I'm not sure you'll find a gearbox more compact than the versa planetary with the same reduction options. That being said, what kind of a reduction are you looking for? And with what motor? If you're using a high power motor with a larger reduction, any standard spur gearbox will be massive in comparison to the VP's.

[Fluffaluffagus]

We are using are the RS-775 motors.

[MrForbes]

How fast does the output shaft need to turn?

[Fluffaluffagus]

It's not speed were looking for it's power. We have a 5 foot arm that needs to move up and down. On the VP's we were looking at the 100:1 ratio before we realized that three layers would be too big for our robot.

[MrForbes]

You can still define the requirement for the gearbox by using speed. Then you can figure out what ratio you need.

Say, you want your arm to move 90 degrees (from horizontal to vertical, for example) in about one second. That's 0.25 revolutions per second, or 15 revolutions per minute. An RS775 motor has a speed at it's "sweet spot"of about 15,000 rpm. That means you need to have about 1000:1 reduction to have the arm travel at the speed.

I'm making a lot of assumptions about your robot design, since you provided no details yourself. If you want more useful suggestions, you really need to provide us with a bunch more information about your robot.

[Mike Schreiber]

Mr Forbes is correct you need to be A LOT more specific if you want real help.

What gear boxes did you blow? Was it while going over an obstacle? Perhaps the fix isn't in the gearing, but in damping or counter-weighting the arm?

What is your packaging constraint? Can a wider but shorter gearbox using spur gears fix your issue? Are you already using a chain and sprocket? I assume this because otherwise a 5 ft arm with only 100:1 reduction would be way too fast to control. You should really be gearing for a target speed. Could you consider a different motor with a slower free speed such as a miniCIM?