pic: Quick-Change Motor Drive Module 1

[Kevin Thorp]

Originally Posted by dradel

what gear box is that?

It's a Nordex GRX-A2-10 (10:1 speed reduction). Link

We've had very good luck using them to drive 6" wheels, but our sister team (342) stripped one or two out driving 12" wheels. I think they used a 20:1 ratio.

[ThaddeusMaximus]

What advantage does this yield over VersaPlanetaries?

Edit: I see other pics now. Thought the idea here was swap in different motors.

But why fix your gear ratio?

[Kevin Thorp]

Originally Posted by ThaddeusMaximus

What advantage does this yield over VersaPlanetaries?

Edit: I see other pics now. Thought the idea here was swap in different motors.

But why fix your gear ratio?

Yes, you have a good point. We already have a number of these worm gearboxes with a 10:1 gear ratio. If that doesn't fit our strategy in 2017 we'll need to add a chain or belt drive to adjust the final drive ratio.

Then our "quick-change drive module" is not so quick to change.

[Kevin Thorp]

Originally Posted by Kevin Thorp

It's a Nordex GRX-A2-10 (10:1 speed reduction). Link

We've had very good luck using them to drive 6" wheels, but our sister team (342) stripped one or two out driving 12" wheels. I think they used a 20:1 ratio.

Hmm.. It looks like a few different vendors are selling the same gearbox: Nordex, SPD-SI and Torque Transmission. I wonder which one is the manufacturer?

[Ari423]

How are you attaching the shaft to the gearbox? We struggled with that problem when we used them last year and ended up using a 5/8" hollow output and welding in a 5/8" OD to 1/2" ID with 1/8" key adapter so we would have a keyway. In the end this solution didn't work very well because the keyway was oversized which introduced slop into the system. We really didn't want to use the built-in roll pin because we didn't want to machine the pin holes into the shafts and were afraid of them shearing during competition and not being able to replace them. How did you solve this problem?

[Kevin Thorp]

Originally Posted by Ari423

How are you attaching the shaft to the gearbox? We struggled with that problem when we used them last year and ended up using a 5/8" hollow output and welding in a 5/8" OD to 1/2" ID with 1/8" key adapter so we would have a keyway. In the end this solution didn't work very well because the keyway was oversized which introduced slop into the system. We really didn't want to use the built-in roll pin because we didn't want to machine the pin holes into the shafts and were afraid of them shearing during competition and not being able to replace them. How did you solve this problem?

We inserted a 5/8" OD shaft then drilled & tapped a couple M4 holes into both the gearbox & shaft, using the existing roll pin hole as a pilot. Then installed a couple M4 screws. This seems to hold up well in competition and doesn't introduce much play.

Nordex said they could manufacture these gearboxes with 1/2" hex hollow shafts if there was enough interest from the FRC community. That would make the wheel shafts super simple!

[Drivencrazy]

Just a word of caution: An input torque on the "output" shaft can cause a significant amount of stress in the gearbox casing leading to cracking.

For instance someone pushing you from the front or rear would create a reactionary torque in the wheel. Which would then get transmitted through the gears and into the worm gear shaft which would press against the plastic housing of the gearbox.

We sourced some of these from Torque Trans for the 2011 season and had a similar issue arise several times.

[Kevin Thorp]

Originally Posted by Drivencrazy

Just a word of caution: An input torque on the "output" shaft can cause a significant amount of stress in the gearbox casing leading to cracking.

For instance someone pushing you from the front or rear would create a reactionary torque in the wheel. Which would then get transmitted through the gears and into the worm gear shaft which would press against the plastic housing of the gearbox.

We sourced some of these from Torque Trans for the 2011 season and had a similar issue arise several times.

Yes, Team 342 had a couple Nordex gearbox failures using 12" wheels. This adds tremendous stress to the gearbox housing during pushing & abrupt stops.

Team 3489 has used them for 3 years, with no failures:
2014: Two worm gearboxes driving four wheels: two 6" Omnis and two 6" HiGrip
2015: Four worm gearboxes driving four 6" Mecanums
2016: Four worm gearboxes driving four 8" pneumatic wheels & six 4" Colsons.