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After the match has been played, the power from the robot / motor will be turned off by the field system, and the robot will slowly go down. By adding this extra custom made stage where an pneumatic cylinder “shoots” a pin through the gearbox, the rope can no longer unwind and the robot will not go down.
Below some screenshots, but to make it more clear you can find a CAD model of this brake on our grabcad page: Custom break REV Planetary Gearbox