pic: Coaxial Swerve Drive Module with 2-speed Ball Drive and Nitrile Tread

[mplanchard]

Beautiful model. Thank you for sharing. Marie

[Bryce2471]

I really love this design overall. I've wanted to design a swerve with a single reduction ball-shifter for quite some time. I do have some questions and concerns though.

1. It looks like there is no thrust bearing above the vertical miter gear. This is not a big deal by its self, (We used thrust washers last year) but it will increase the speed of deterioration on the gears, and decrease efficiency in that gear-set. It also looks like you're planning on using the VEX Pro aluminum Miter gears. This is also not a big deal, lots of team use them, but I suspect the fact that they are aluminum will increase wear speed. With those two things combined, your drive performance may not suffer, but you will probably find yourselves replacing the miter gears pretty often. What is the process for replacing a miter gear? How long will it take?
2. How many man-hours will you spend to machine all the parts? How about to assemble the modules? I feel like you could have designed a module with the same performance, that would have been much less resource demanding to build.
3. What kind of bearing are you using to move the robot's weight from the red base plate to the top of the castor? In the cross section, it looks very thin.
4. Not sure if it is a problem or not, but I couldn't help but notice that your pneumatic cylinder is mounted to a plate, that has standoffs to a plate, that has standoffs to a plate, that is stood off from a plate, that has standoffs to a plate, that is mounted to your frame. Not sure why, but that makes me cringe a little.
5. What gears are you using on the ball-shifter shaft, and as the CIM pinions?

[Aren_Hill]

Originally Posted by Bryce2471

1. It looks like there is no thrust bearing above the vertical miter gear. This is not a big deal by its self, (We used thrust washers last year) but it will increase the speed of deterioration on the gears, and decrease efficiency in that gear-set. It also looks like you're planning on using the VEX Pro aluminum Miter gears. This is also not a big deal, lots of team use them, but I suspect the fact that they are aluminum will increase wear speed. With those two things combined, your drive performance may not suffer, but you will probably find yourselves replacing the miter gears pretty often. What is the process for replacing a miter gear? How long will it take?

VEXpro Bevel gears are 4140 hardened steel not aluminum.

-Aren

[magnets]

This is a fantastic design. There have been many designs of two speed swerves posted over the years, but nothing has come close to what you've put together.
I know from looking at your swerve design from last year that you guys shouldn't have trouble machining the parts in this design, but I've got to ask, how do you guys even have time to make these parts and finish the robot on time? What sort of tools do you have, and how many people do you have working?

[Bryce2471]

Originally Posted by Aren_Hill

VEXpro Bevel gears are 4140 hardened steel not aluminum.

-Aren

Thanks Aren, that makes a lot more sense. I was actually amazed that the gears seemed to be holding up.

I'm still curious how the miter gears would be replaced, and how long it would take.

[Jared]

Originally Posted by Bryce2471

I really love this design overall. I've wanted to design a swerve with a single reduction ball-shifter for quite some time. I do have some questions and concerns though.

1. It looks like there is no thrust bearing above the vertical miter gear. This is not a big deal by its self, (We used thrust washers last year) but it will increase the speed of deterioration on the gears, and decrease efficiency in that gear-set. It also looks like you're planning on using the VEX Pro aluminum Miter gears. This is also not a big deal, lots of team use them, but I suspect the fact that they are aluminum will increase wear speed. With those two things combined, your drive performance may not suffer, but you will probably find yourselves replacing the miter gears pretty often. What is the process for replacing a miter gear? How long will it take?
2. How many man-hours will you spend to machine all the parts? How about to assemble the modules? I feel like you could have designed a module with the same performance, that would have been much less resource demanding to build.
?

I don't see how not having a thrust bearing reduces the life of the gears. It may affect the life and efficiency of the 0.375" bearing sitting above it though.

We've done something similar with our climber (3 CIMs on a 10:1 worm reduction) with the worm resting against the inner race of a normal radial bearing, and we saw no issues.

[Tyler2517]

Originally Posted by Jared

I don't see how not having a thrust bearing reduces the life of the gears. It may affect the life and efficiency of the 0.375" bearing sitting above it though.

We've done something similar with our climber (3 CIMs on a 10:1 worm reduction) with the worm resting against the inner race of a normal radial bearing, and we saw no issues.

I can confirm what Bryce2471 is saying we saw reduced life and over time reduced efficiency due to us not having the thrust bearings between the mitter gear and the radial bearing.

[Jared]

Originally Posted by Tyler2517

I can confirm what Bryce2471 is saying we saw reduced life and over time reduced efficiency due to us not having the thrust bearings between the mitter gear and the radial bearing.

Of the gears or of the bearings? Also, did you do a comparison with thrust bearings to see if life improved? I don't see how the gears would have any additional loads on them due to a lack of thrust bearing.

[Tyler2517]

The tops of our bevel gears deteriorated from where they were rubbing the bearings at. We swaped them out for milled down bevels with the thrust bearings and have not had any problems.

[Jared]

Originally Posted by Tyler2517

The tops of our bevel gears deteriorated from where they were rubbing the bearings at. We swaped them out for milled down bevels with the thrust bearings and have not had any problems.

That makes sense. I think that the original poster might have room to put a thrust washer in there, which hopefully will help.

[Bryce2471]

Originally Posted by Jared

I don't see how not having a thrust bearing reduces the life of the gears. It may affect the life and efficiency of the 0.375" bearing sitting above it though.

We've done something similar with our climber (3 CIMs on a 10:1 worm reduction) with the worm resting against the inner race of a normal radial bearing, and we saw no issues.

I'm not sure exactly why, it's just something I have observed. I think it could be because a thrust bearing that rests on the outer race of a radial bearing provides a wider base of support for the miter that keeps it from flexing the shaft it sits on. You're correct about it affecting the life of the bearing above that supports the gear.

[Lyler1]

Hi!

My team has been designing drivetrains this past off-season and I was very intrigued by your guys' design. I was wondering if you could tell me the name of the student who designed it and perhaps a way to speak with him/her, because my team is very curious and may want to ask some questions. Thanks a ton!

[Tyler2517]

Originally Posted by Lyler1

Hi!

My team has been designing drivetrains this past off-season and I was very intrigued by your guys' design. I was wondering if you could tell me the name of the student who designed it and perhaps a way to speak with him/her, because my team is very curious and may want to ask some questions. Thanks a ton!

You could ask on here you would have a much larger base of responses.

Originally Posted by Tyler2517

You could ask on here you would have a much larger base of responses.

A lot of low quality, second hand responses aren't as good as a few high quality, straight from the source responses.

[Abhishek R]

Originally Posted by Andrew Lawrence

A lot of low quality, second hand responses aren't as good as a few high quality, straight from the source responses.

It's possible that the responses are high quality, and that anything wrong could be confirmed/dispelled by the OP.

Although, you could probably also reach out to 'Kevin Ainsworth' via PM.