Compound Gear Compound Gear davidovitsh (Civil/Environmental) (OP) 22 Oct 17 17:08 How much is the maximum RPM that have been ever achieved by the using of sequence of compound gears. RE: Compound Gear JohnRBaker (Mechanical) 22 Oct 17 18:32 Depends on the size. I would suspect that for a set of smaller gears, the speeds could be quite high. John R. Baker, P.E. (ret) EX-Product 'Evangelist' Irvine, CA Siemens PLM: UG/NX Museum: The secret of life is not finding someone to live with It's finding someone you can't live without RE: Compound Gear BrianPetersen (Mechanical) 23 Oct 17 20:54 Drive mechanisms for centrifugal superchargers (automotive applications) can have very high output speeds. The centrifugal supercharger on a Kawasaki H2 motorcycle drives the supercharger at 9.2 times crankshaft speed, and max crankshaft speed is 13,000 rpm, so supercharger rpm would be 120,000 rpm under those conditions. The final output stage is a planetary-geared speed increaser with an 8:1 speed ratio. RE: Compound Gear EdStainless (Materials) 24 Oct 17 19:11 I have a hand held mini-grinder that has a 40k rpm motor and ~130k rpm output. The guys that built it said that they tested one with ~250k rpm output, but it too bulky and ran hot. = = = = = = = = = = = = = = = = = = = = P.E. Metallurgy, Plymouth Tube RE: Compound Gear jgKRI (Mechanical) 25 Oct 17 15:06 Speeds achieved in the real world are directly and inversely related to size of the gears, as others have stated. You'll also find that if you do the math, the speed is directly limited by contact velocities. There's an upper limit based on gear material.