pic: 775pro H-drive update

finished putting this together,
Uses 4 of the gearboxes I just finished making.

center wheel direct driven, chains to the front and back.

I’ll probably re-arrange it so that the back wheel is direct driven and put the 2nd gearbox right next to it.

What is the point of the two separate gearboxes on each on each side? Why not use one gearbox per side?

Additionally from looking at your gearbox it looks like you may have 3 bearings inline with one another on the same ridgid system. That would cause the shaft to be over constrained and bind up. You want the shaft supported at the back plate and the bearing in the tube. The one that is on the plate bolted to the tube is a liability.

2 in the gearbox and 1 in the tube is fine, as you can use the tube bearing to align the gearbox. What you don’t want is something like 3 bearings in a row in a single gearbox where you’re really overconstraining it in a short length of shaft.
Agreed that you could consolidate your gearboxes.
EDIT: You still only have 1 screw per side in some tubes for your gusset setup. If you don’t add more holes you’re in for a bad time.

I would disagree. As soon as you bolt the gearbox to the tube the tube becomes an effective part of the gearbox since after two books the gearbox is fully constrained to the tube.

Three 775’s wouldn’t fit around a 60tooth gear, and I hadn’t figured out a four motor box.

Three bearings isn’t that bad if you can be accurate enough.

Please tell me this thing is going to have 8 omnis! 8 omni drive is friggin’ slick!

Two traction wheels at the back and 4 Omni’s

Yeah I haven’t changed the brackets because we already have a cad of the ones we used last year that at 4 bolt triangle shaped ones and I’m not making this super accurate right now

How are you planning on doing H-drive with two traction wheels? I can maybe imagine it if the strafing wheel is actuated (which you should do if you want it to run smoothly btw) but you’re going to have a hard time strafing if you’re trying to also power through scrub on two traction wheels.

Is there a plan for a suspension? The only time I have been a part of building an H-drive, we skipped the suspension for simplicity. We figured the floor would be flat in most high school gyms (district format in MAR). It worked, kind of, but, there was still some slippage- I think it’s just hard to rely on 5 spread out points of contact, or in this case, 7 points of contact.

Also, traction wheels?

A piston with a wheel will jack up the back of the frame to lift the traction wheels off the ground slightly

Given the spacing of the frame, have you considered setting up the gearbox so that you could have 2 motors on each side (facing each other)? That way the only spacing you’d have to deal with is the spacing between the pinion gears.

You should consider making this the strafe wheel, solving both questions - how to get the traction wheels off the carpet and how to apply a steady force to the carpet with the strafe wheel in one shot.

No I hadn’t thought about flipping one set, the could work to have three motors in this gearbox, but it’d still need to be redesigned for four motors.

That’s true, but keep in mind you have a few inches of shaft between the gearbox and the outer part of the tube. Bolt tolerances are super loose and if you rely on them to align your bearings you’ll be in for a bad time.
Because the bolt hole tolerances are so loose, you can easily skew your gearbox shaft if you rely on just those to align your bearings.
The WCP gearbox uses their gearbox bearing block as a possible solution to align the gearbox.

On the topic of actuated wheel drives, anyone seen any good grasshopper drives lately? I feel like 3310 may have done it, but I’m not sure.

624 did it again this year

624 did grasshopper? I thought they liked butterfly.

Their presentation from 2014 calls it grasshopper.