pic: Tiki Tech Transmission

WCD Motor Over Frame Transmission by FRC3880 - The Tiki Techs. This transmission uses the currently available dog gear and pinion gear sets from WCP. Including encoder mount. This transmission plate can be milled as shown or non voided flat plate. Motors and encoder can be mounted in either orientation. Shown version is for chain in tube setup which makes the transmission less than 2.5" thick. Not including pneumatic. =)

Very cool. Is this a 2 cim or 3 cim setup? What is the weight?
Also, you mention that this is for WCD. Are the sprockets inside the gearbox or designed to be outside? If it’s the latter, I suggest changing it to the former so that the gearbox is easier to mount.

This is setup as a 2 CIM. One CIM one Mini CIM for our drive setup. We will be running 4 of these, potentially. Until we get our CNC and can mill larger items. The sprockets and chain that this transmission is designed for are inside the frame rail. Though you can make the spacers longer and it is the same sprocket setup as the WCP transmissions.

The weight with mini and full size CIM is 14.7lbs

including the encoder :wink:

I would not feel comfortable putting half the weight of my robot into gearboxes. This is even ignoring the breaker issues of an 8 motor high traction drive.

Agreed. It looks like a very nice gearbox, however. Especially with your drive setup, which looks like an 8WD with some nice elements (chain in tube, 6-sides), I’d reevaluate whether the best use of your resources is four independent, custom gearboxes. Regardless of whether you want to do 8-motor drive, the redundancy in weight running four gearboxes seems like an exceedingly problematic limiting factor when considering the rest of your robot.

But that’s just like, my opinion man.

Really like some of the design that went into this (and the full chassis CAD)-- the motor controller mount between the gearbox is cool, and I like how your motors match the angle of your frame on the sides. There are a lot of cool elements here and I hope you guys can capitalize on what you learn with this offseason drive to make a killer drive train in the 2015 season!

What is the idea behind having three stages? The way i see it you could probably do the same thing you have there with only two axles making it a bit lighter.

For your drive purposes, I highly recommend that you just design a 4 cim gearbox. Or, better yet, decrease to 3 cims.
Also, instead of using gears to combine the motor output, I would take a look at 192’s design which uses belts for the first stage of transmission. You can combine the outputs of all the cims for a lot less weight that way instead of using gears. Then just use the shifting stage to shift between a 14:40 and a 34:60 stage (both of those shifting gears are sold by WCP) to get the last transmission stage.

Did you mean 14:60 and 34:40?

Bleh yes. Sorry, I was thinking of the ball shifting gears for the primary, and the dog shifting for the secondary.

You are making a drivetrain that is 58.8lbs without the frame? Are you making the rest of your bot out of carbon fiber?

And mechanisms to run on hope and dreams while drawing that much power for that drive train…phew

REPEAT of what was posted in the Prototype Frame…

Ok my bad. I am new to the iProperties thing.

This should have been caught by me, knowing that the CIMs together weigh about 5lbs.

There is no way that transmission weighs 9 lbs!!! More like 3.

The transmission is basically a hybrid of a WCP 2 CIM DS, 2.15lbs. and 3 CIM DS, 3.5lbs. Weight will be between that since it is basically a stretched DS if you will. A 2CIM DS with one extra idler. We went with an idler gear instead of belts. Much easier for us, we had it on hand.

The entire transmission was designed using the existing gears from our 3CIM DS making it easy to test by just replacing the frames. Future orders of different gear ratios from WCP will just work.

Last year we used the WCP 3CIM DS and are extremely happy with it. Never had any issues with breakers tripping on our 6 wheel WCD, but space was tight.

We wanted a stretched 2 CIM DS, if you will. That was set up for in-frame chain setup and over the frame motor orientation. (see hex frame).

Being able to orientate the motors in either direction and a quick and easy encoder placement was the goal.

Our competition bots have always had a post tapped into the front or rear axle that the encoder used. Not always pretty…

Something different for us…

We are looking at the WCP DS for next season; 3 and 2 cim. How happy were you with them? Why?

We ran the WCP 3 CIM on our last robot and were very pleased.
As a team with limited machining tools available and even more limited machine shops.
Well ok, no real machine shop on the island… It was a great way for us to move to a more competitive drivetrain.
I would recommend these transmissions as an easily incorporated subsystem.

We ran 5.5/15fps and never tripped the breaker, didn’t even get warm…

Originally we ran the Versa wheels, but they couldn’t handle.
This is what happened to our tires in our first practice match.
The robot ran into the wall during autonomous and drove constantly in low gear. Luckily they were not too expensive…
Changed to Colson at worlds, not going back. In fact our new Colson wheels arrived last week! :smiley:

The power was great!

First time running a shifter and the shifting never failed.

If our CNC doesn’t arrive we would use them again, if it works with the new game… Our poor CNC It is on a boat, sailing 1000’s of miles to us. Hope that hurricane last week doesn’t add another month or so.

The 3 CIM DS has a fairly large footprint. It is why we are toying with the motors over the frame.
(New rendition is a one piece 4 motor with the pneumatic shifter under the motors)

Hope this helps.


Yes it does ty! Although I am jealous now of you CNC!