Hello fellow PF members, This is my first post. I am wondering if there is a mechanism that alters the gear ratio in worm gear-worm wheel setup.. Something like a variable pitch worm gear that can be used instantaneously to alter the gear ratios. If not for worm gear, is there anything in any type of mechanical gear system? Thanks in advance. --- Edit: BTW, when I said worm gear, I meant the worm itself & by worm gear I meant something like a spur/helical gear.