Custom Gear Boxes

[Cash4587]

Is there a way to repackage the Ball Shifter that instead of shifting into high gear it shifts into like a brake? Such that in a way it "locks" the gearbox so that none of it can move, or at least the output shaft doesn't move? Thanks

[Joe G.]

Set things up so that your gearbox behaves like a single speed gearbox through one of the ball shift gears, and bolt the other gear to the shifter's frame.

[T^2]

Originally Posted by Joe G.

Set things up so that your gearbox behaves like a single speed gearbox through one of the ball shift gears, and bolt the other gear to the shifter's frame.

Depending on how many motors you used, there's a distinct possibility of shearing the ball-locking pin within the shaft, or at least destroying the coupler that holds it to the pneumatic cylinder.

[Joey Milia]

Originally Posted by T^2

Depending on how many motors you used, there's a distinct possibility of shearing the ball-locking pin within the shaft, or at least destroying the coupler that holds it to the pneumatic cylinder.

There shouldn't be any torsional force on that inner shaft. All the force from the motors is transmitted through the balls to the drive shaft, not to the inner shaft.

[T^2]

Originally Posted by Joey Milia

There shouldn't be any torsional force on that inner shaft. All the force from the motors is transmitted through the balls to the drive shaft, not to the inner shaft.

The flat of the bulge of the inner shaft is not centered on the holes, meaning that as the gear turns, it exerts force on the balls inwards as the balls ride partially on a 45 degree slope. This effects a linear force on the inner shaft along the axis of said shaft. (Mind you, I've never damaged the coupler myself, so this is all theoretical.

[EricH]

Originally Posted by Joe G.

Set things up so that your gearbox behaves like a single speed gearbox through one of the ball shift gears, and bolt the other gear to the shifter's frame.

Or set a third gear in contact with both the gear you don't want to use and the gear it connects to. That'll stop motion on that side for sure. (Ever see a gear try to rotate two ways at once?)

If you have a linear force along the inner shaft, you might bend something, but I doubt you'll break it via torsion. Might get a little bit of bending, though that shouldn't be too bad of an issue.

Probably a better way to handle braking is to have something rigged--servo or pneumatic cylinder or electric solenoid--such that when the brake is activated, a pin is shot through a hole in some solid frame member, through a hole in a gear or other rotary part, and through a hole in a solid frame member immediately opposite. Now, that might be a little more complex than just locking the gearbox, but I think it might address the concerns about the pin in the ball shifter.

[mman1506]

It would probably better to use some sort of brake pad and disc to brake that allows for some slip.

[Mk.32]

Originally Posted by mman1506

It would probably better to use some sort of brake pad and disc to brake that allows for some slip.

Get some cheapo scooter disk breaks/disks for $20 or so a set and a small piston to drive it?

[EricH]

Originally Posted by mman1506

It would probably better to use some sort of brake pad and disc to brake that allows for some slip.

Originally Posted by Mk.32

Get some cheapo scooter disk breaks/disks for $20 or so a set and a small piston to drive it?

If it was up to me, I'd do some looking into the appropriate calculations for the force you need to apply for that sort of thing. The calculations are pretty simple, if you happen to have the ratings of the brake pads, as I recall (I don't have them really, really handy, though, or I'd post them--it'll be a couple of days or so before I can post them up).

Now, this is assuming that the intended application would allow for some slip. If, OTOH, you need NO slip, then any brake/clutch type as discussed will need to be designed to hold more than the expected force needed to stop the robot from moving, lots more force.