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Unread 10-06-2014, 17:22
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Re: The in-wheel swerve shifter!

Quote:
Originally Posted by asid61 View Post
So they need human input then? I swear I saw autoshifting versions.
I'm opening up the CAD so I can see what happens when you slow down.

EDIT: yup, the dog bounces back and forth like crazy while rubbing against the shifting elements when you slow down, which would completely destroy the teeth on the mating elements. I'm going to find a solution to that.
DOUBLEEDIT: So what would happen is this:
1. The dog slows.
2. The dog is pushed into the other gear by the obtusely angled faces.
3. The obtusely angled face there pushed the dog back.
4. Repeat steps 2-3 until the dog contacts the flat of the teeth and cannot shift out of its current gear.
5. The gear that it is in is forced to slow down slightly until the dog bounced back into the other gear.
Repeat until slowed. There would be a lot of bouncing, but nothing too high load except for the rubbing at the end. Another thing to test under load, although this is a much more serious issue.

Of course, that doesn't matter if you are doing something at a constant 100% speed like loading a spring or climbing, but for drive this seems like a problem.
This is what I was trying to talk about earlier. As the dog oscillates during slow down / direction changes, the gears are being alternately loaded almost all of the time, though the duration of each individual load condition might not be that high. This is going to resolve as inertia that prevents the CIM from fully slowing down as quickly as a CIM under no load, unless there's a very significant delay between shifting halves.

Another condition that might behave oddly is what happens if you shift under load, i.e. to begin a pushing match. While the dog is "in between" gears, your wheels offer essentially no rolling resistance. What if a wheel is spinning the opposite direction you're trying to drive it? It seems like no matter how long the shift window is, you're going to be dealing with either or both of these problems to varying degrees.

I ain't trying to hate on your design, just trying to figure out if there are ways around these issues.
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