pic: VR-001: A Jersey Voltage Simple Hex Frame

[Cash4587]

Originally Posted by Oblarg

In my experience, the center of a robot can get crowded to the point where it's nice to be able to pull the wheels with the axles in place, which is why I asked. Also, you can't pull the axle on the direct-driven wheel without pulling the gearbox.

Just something to think about.

No, you can pull the axles out, like out of the robot, like not into the robot, like out of the frame side, where the wheels are. As for the one on the gearbox, that is a different story. However, the only reason my team pulled off our wheels this year was to change the belts on the DT, which was because of ratcheting due to machining error. If we would have used tensioners on the system, we would have never needed to pull the wheels off. Yeah it's a "nice to have" but if this system ends up working, it will be far more effective than what we used in 2014.

[Cash4587]

http://prntscr.com/506kjk

Here is the DT with added support to the bump outs.

[Oblarg]

Originally Posted by Cash4587

No, you can pull the axles out, like out of the robot, like not into the robot, like out of the frame side, where the wheels are.

You can do that, but then they come all the way out of the bearing blocks (and ostensibly any sprockets you have on the other side are then loose, too).

Not saying you should change your design; it's a minor concern. It's just that I've spent a lot of time servicing drives, and little details like this are worth thinking about, if nothing else.

Originally Posted by Cash4587

http://prntscr.com/506kjk

Here is the DT with added support to the bump outs.

Cool, that certainly would be harder to break.

[Cash4587]

Originally Posted by Oblarg

You can do that, but then they come all the way out of the bearing blocks (and ostensibly any sprockets you have on the other side are then loose, too).

Not saying you should change your design; it's a minor concern. It's just that I've spent a lot of time servicing drives, and little details like this are worth thinking about, if nothing else.



Cool, that certainly would be harder to break.

Correct, Service of drives are definitely a pain. We got to the point this year where we could have our entire drive train dismantled (gearboxes off, axles off, bearing blocks out, belts off, sprockets off, motors unplugged) and back together again in less than the time it takes for us to be back to the field for our next elimination match, so about 12 or so minutes. We train our pit crew well and teach them that there are definitely trade-offs to running the type of setups we run. We do however consider all options prior to final design.

[Cash4587]

One thing I just noticed is that, there is no way to actually run this setup pictured. The gearboxes will need to be on opposite ends of the robot due to the axle length of the gearbox. This is not a problem, just will need to be re-worked.

[JesseK]

This is pretty nifty, but I would worry about the chain runs affecting the match-to-match reliability of 'drive straight' in autonomous.

Eventually the four wheels in the middle will make a trapezoid (or some other such non-square 4-sided shape) rather than a rectangle since the chains will stretch at different rates. This can be mitigated by directly running the chains from the gearbox to both sets of middle wheels. The typical WCD 6WD experiences this with nominal effects since the middle wheel locations are always constant.

The gearboxes will need to be on opposite ends of the robot due to the axle length of the gearbox.

If you have a lathe, could you cut the gearbox output shaft and re-tap the hole in the end?

[Lil' Lavery]

The wheel service point is one I didn't realize last night, but is an important one. The biggest reason 1712 is looking at using Versachassic/West Coast Drive this upcoming season is wheel wear. We love versawheels, but hate having to spend significant effort in replacing them once the tread wears. Obviously using colsons will mitigate this in your design, but your design also neutralizes one of the best features of having cantilevered drive axles.

[Madison]

Presumably, the power transmission between wheels is hidden inside the tubing?

I'm having trouble wrapping my head around how that all gets assembled -- it seems possible but not pleasant -- and it seems like it'd be a tremendous amount of work to repair a problem with those components after assembly. You'd have to take apart the entire frame.

Edit: It's also plausible that they're just not modeled since, after looking closer, there are no axles in any of the wheels.