Gearbox issues

[MrNumbskull13]

I recently built Sariel's 2 speed gearbox and I was wondering how could I make a smooth and quick gear changer. I can only make a manual gearbox so does anyone have a solution? Thanks.

Edited April 8, 2013 by MrNumbskull13

[07jkearney]

Who's Serial? :P

A medium motor and a mini linear actuator combined with Sariel's 2-speed heavy duty gearbox works smoothly, but not too quickly :)

Edited April 8, 2013 by 07jkearney

[MrNumbskull13]

Thanks for pointing out my mistake, edited it now. :) Also I'm using an XL motor for propulsion and I don't own any mLAs :/

[Bzroom]

A worm gear should give you a smooth and secure change over. The sliding nature, and open ends of the worm gear also lends itself to applications that have a limited motion, like throwing a switch. Since the worm gear has such a massive reduction and back-drive friction coefficient, you can gear up the input so that it makes the switch very quickly.

You could connect the gear change switch to a small gear driven by the worm gear, or you might research solutions to actuating a pneumatic switch, often referred to as an auto-switch, for ideas on how to toggle your gear switch.

[MrNumbskull13]

Thanks! I thought about using a worm gear but they are very slow so ill try gearing it up :)

[Saberwing40k]

Thanks! I thought about using a worm gear but they are very slow so ill try gearing it up :)

I wouldn't do that. gearing up can put a lot of stress on the motor and the drivetrain. You'd be better off mounting the worm gear on the sliding element, and having the gear be fixed. Or, you could use a big linear actuator.

[allanp]

Or just use a gear rack or simple crank. If that is too fast or weak, gear them down slightly. A well designed crank mechanism will work fast, smoothly and reliably whilst also locking the gearbox in gear.

[AndyCW]

I built one of these gearboxes with 2 RC Buggy motors. The shifting mechanism worked flawlessly. Here is a video of the shifting mechanism in operation.

It uses a PF medium motor, a 24t clutch gear, a worm gear, a 2 stud lever arm, and a 9 stud link to create 1 stud of travel. It needs stops to prevent over travel and the clutch gear prevents the motor or framework from becoming too stressed.