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Reverse 2 CIM SS Gearbox Render

Landon K

By: Landon K
New: 07-19-2018 09:31 PM
Updated: 07-19-2018 09:31 PM
Views: 780 times


Reverse 2 CIM SS Gearbox Render

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07-20-2018 04:21 AM

AriMB


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Looks nice. How does it attach to the frame?



07-20-2018 08:31 AM

Landon K


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

The bottom four bolts go through the first wall of the frame 2x1, this render might make more sense for how its mounted. This is my first gearbox so any criticisms or questions are welcome.



07-20-2018 09:44 AM

cad321


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

What ratio are you running and with what size wheels? It looks like 4in wheels from the picture but not totally sure.



07-20-2018 09:49 AM

Landon K


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

It is a 4.98:1 so about 15 ft/s adjusted with a maxed out weight robot (like my team always builds) with 4 inch wheels. Our 2018 robot had a high gear of about 16 ft/s and it was a bit too fast, so I dropped it down a bit.



07-20-2018 11:28 AM

BobbyVanNess


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

For non-torque transmitting sections of shafts, I highly recommend using snap rings. Shaft collars have a tendency to become loose under high load applications, and snap rings are just pretty easy and painless in general.

Additionally, if you were to flip the bearing flanges towards the inside of the box, the idler shaft could be retained by turning the hex down to 1/2" round and using round bearings.



07-20-2018 12:08 PM

Landon K


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by BobbyVanNess View Post
For non-torque transmitting sections of shafts, I highly recommend using snap rings. Shaft collars have a tendency to become loose under high load applications, and snap rings are just pretty easy and painless in general.

Additionally, if you were to flip the bearing flanges towards the inside of the box, the idler shaft could be retained by turning the hex down to 1/2" round and using round bearings.
That is great advice, but my team doesn't have a lathe so I was trying to design for our capabilities. That all totally makes sense, thanks for the feedback!



07-20-2018 03:34 PM

mman1506


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

We made a similar gearbox in 2015 that you might find interesting. We used a belt for the second reduction.
https://www.chiefdelphi.com/media/photos/41334



07-20-2018 06:24 PM

Landon K


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by mman1506 View Post
We made a similar gearbox in 2015 that you might find interesting. We used a belt for the second reduction.
https://www.chiefdelphi.com/media/photos/41334
I considered the belt as the second reduction was nearly 1:1 but couldn't bring myself to put a belt holding the torque of an entire (half) of a drivetrain. I like the idea of mounting the CIMs on the inner plate to bring them inside more and shorten the wheel well. Do you have any more pictures of that gearbox?



07-20-2018 06:35 PM

mman1506


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by Landon K View Post
I considered the belt as the second reduction was nearly 1:1 but couldn't bring myself to put a belt holding the torque of an entire (half) of a drivetrain. I like the idea of mounting the CIMs on the inner plate to bring them inside more and shorten the wheel well. Do you have any more pictures of that gearbox?
I'll grab some later today. We used a 16mm GT2 Belt and it had absolutely 0 issues. Admittedly this was in 2015 but other teams have used similar belts with similar pulley sizes in their drive train without issue in other years (most notably 971)



07-20-2018 08:42 PM

GeeTwo


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by mman1506 View Post
We used a belt for the second reduction.
If you're planning to use belts before the first wheel, I'd recommend running separate belts from the gearbox to the wheels just fore and aft of it. That way, the loss of one belt doesn't necessarily mean loss of all drive on that side. It also means you won't have to put three belts on an axle.



07-20-2018 09:02 PM

mman1506


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by GeeTwo View Post
If you're planning to use belts before the first wheel, I'd recommend running separate belts from the gearbox to the wheels just fore and aft of it. That way, the loss of one belt doesn't necessarily mean loss of all drive on that side. It also means you won't have to put three belts on an axle.
I don't think you understand what a second reduction is...

Here's some additional images of the gearbox https://imgur.com/a/d6UYoxo



07-21-2018 05:20 AM

Landon K


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Thank you everyone for the input! Also, if anyone is looking for a CADathon partner, send me a PM....



07-21-2018 10:07 AM

pandamonium


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by Landon K View Post
The bottom four bolts go through the first wall of the frame 2x1, this render might make more sense for how its mounted. This is my first gearbox so any criticisms or questions are welcome.
Gear box looks great! How do all of the wheels get power? Are you running belts on the outside?



07-21-2018 10:27 AM

Landon K


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by pandamonium View Post
Gear box looks great! How do all of the wheels get power? Are you running belts on the outside?
I finished the whole frame last night, the middle belt run is on the inside thanks to the pulley "inside" the gearbox and the other belt runs to the outside wheels are on the outside. The pulleys are 30T and the belt is 15mm wide HTD.
Heres a render of the whole drivetrain...https://imgur.com/a/uXpHsje



07-21-2018 06:02 PM

GeeTwo


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by mman1506 View Post
I don't think you understand what a second reduction is...
I think I do; there's no reason the pulleys at the wheel ends of the belts have to be the same size as the one(s) on the gearbox.

We used a third level of reduction on our 2016 STRONGHOLD robot executed in the form of two separate chain runs going from the TB mini output shaft to two different wheels on each side. That TB-mini shaft also drove a little-used 4" twice-reduced wheel just because it could and there were cases with the rock wall and moat where it might help, but for the most part, we drove on our thrice-reduced 8" wheels.



07-21-2018 06:09 PM

mman1506


Unread Re: pic: Reverse 2 CIM SS Gearbox Render

Quote:
Originally Posted by GeeTwo View Post
I think I do; there's no reason the pulleys at the wheel ends of the belts have to be the same size as the one(s) on the gearbox.

We used a third level of reduction on our 2016 STRONGHOLD robot executed in the form of two separate chain runs going from the TB mini output shaft to two different wheels.
How would you possibly run 3 16 mm belt runs in this style of packaging in any sort of practical way? It'd be a mess. Design and test your stuff properly and you won't have an issue. Belts shouldn't break when properly used (how often do you see kitbots break belts under normal use?)



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