Gearbox Shifting Issue

[Remy G]

Hi, so my team has been experimenting with kicking the ball with a surgical tubing design. We are essentially winding back the kicker by connecting a cord to the output shaft of an AndyMark Supershifter and running it, and then putting the gearbox in neutral(we removed one of the two gears to create a neutral).

The problem is that when we put the gearbox into neutral, the output shaft still has a significant amount of drag on it because there are still 2 or 3 gears engaged. Outside of making a custom gearbox (we don't have much for shop access), what could we do to make the neutral free-spinning? Thank you for the help.

[apalrd]

I've never actually seen/worked with the SuperShifters, but I have seen the AM Shifters (the open ones). According to AndyMark, there is an extra stage of reduction on the SuperShifters, which I suspect is after the shifting stage, which is where your problem lies.

We are actually looking into the AM shifters for this, but the AM shifters don't have the extra reduction the SuperShifters have.

in the 2008 season of OCCRA, the Killer Bees built a clutch out of black steel pipe from Home Depot, by putting a piece of 3/4" mounted to the robot as an axle with two pieces of 1" outside them acting as a drum and motor attachment. One piece was fairly short and had a large chain sprocket running to the motor attached to it. The motor was a DeWalt motor, with integrated transmission. That pipe had a notch on the end that went to the other piece. The other piece was long, about 1 1/2' long, with the end cut off to make a notch that the other piece fit into. At the non-notched end of the pipe, we had a pipe flange sitting in a cut C-Channel that would pneumatically pull the second piece away from the first, allowing the clutch to release and the mechanism to fire.
The OCCRA example shows what students can do using no precision tools at all (it was made with a bandsaw and hand tools).
ASCII illustration to hopefully make things clearer:
_________ _______________
| __| |
| | __|
|______| |_______________
Please remember that OCCRA requires no precision machining at all, no welding, and only student work. Thus our devices are not perfect for FIRST robots.

[IndySam]

use this Long SS Hex Shaft am-0147 and you can eliminate the last set of output gears.

[joek]

Originally Posted by Remy G

Hi, so my team has been experimenting with kicking the ball with a surgical tubing design. We are essentially winding back the kicker by connecting a cord to the output shaft of an AndyMark Supershifter and running it, and then putting the gearbox in neutral(we removed one of the two gears to create a neutral).

The problem is that when we put the gearbox into neutral, the output shaft still has a significant amount of drag on it because there are still 2 or 3 gears engaged. Outside of making a custom gearbox (we don't have much for shop access), what could we do to make the neutral free-spinning? Thank you for the help.

you could always put an idle pulley/ sprocket on, and use a spring and a servo to engage/ disengage the drive