Brake disk?

Much like last year we quickly realized that at the end of the match when the power shuts off any robot not locked into place will come tumbling back down. Last year we used a ratchet but this year is a little bit different since what ever we use to lift the robot will have to go in both directions “up and down”. One thing we noticed on robots in previous years were small brake disk from bicycles. My question to you guys is how you would keep the disk brake closed even when the power turns off. Thanks in advance!

Pneumatic solenoids have an “off” position, so having the robot off default to a locked brake would yield the results you’re looking for.

pneumatic cylinder.

If you power it with pneumatics, this is pretty simple. Double acting solenoids will always hold the last commanded position regardless of power. Single acting solenoids will return to a given position when power is removed.

One way would be with an pneumatic cylinder that set the brake when the solenoid is de-energized. Disable De-energizes all solenoids.

I would think that a single acting cylinder, tension with a spring. when the match starts, push air into the cylinder, pushing against the spring, and play the game. When the match ends, the air can vent, and the spring closes the cylinder, gripping the brake lever and braking. or you could just use the air cylinder and not vent, when the match ends, the air will not change, and the brake will be active. Hope that makes sense!

I would challenge the assertion that it has to go both up and down. It is entirely possible (and I think many teams will do it) to have a system that only requires travel in one direction, making a ratchet perfectly valid.

Springloaded Pneumatic Piston

We had a disk brake in one iteration of our 2015 robot, I believe it was controlled with a spring loaded pneumatic piston, the piston was spring loaded so that the disk brake was engaged without air. That did not make it to the final version. for rotational motion I personally prefer the beach bots (330) method of using a giant sprocket ratio and use a van door moter that has a worm gear and can’t backdrive, but both options defiantly work.

These all seem like great ideas but it is for a problem that doesn’t have to exist unless you plan to go higher than 13-15 inches up. In Table 4-1 of the Match Play Section in the rules, the robots bumpers have to be above the 12 inch mark at T=0. This means, unlike 2017 and 2016, the robot is allowed to fall beneath the line after the end of the match. Now I understand the desire to not want to continuously drive the mechanism until the end of the match and have it fall however high your robot climbs (especially if it has other robots on it). Depending on the strategy, you may not have to have a design that locks it at all.