Rack-Pinion Jack 26 November 2019, 19:35 Sorry, your browser doesn't support embedded videos, but don't worry, you can download it and watch it with your favorite video player! Turn pink crank clockwise to move blue rack up. Pink ratchet wheel and yellow pawl prevent the rack from falling down. Push the pawl to bring it out of contact with the ratchet wheel and let the rack move down slowly by holding the crank. « previous mechanism Barrel Cam Mechanism next mechanism » One-Pan Balance load comments Please enable JavaScript to view the comments.