Abstract: Disclosed is an infinitely variable speed transmission, including: a speed changing mechanism for primarily changing power from an engine into a necessary speed ratio, including: a sun gear disposed on an input shaft for transmitting power generated from the engine; a plurality of planet rollers which are disposed around the sun gear at a predetermined distance from each other, each planet roller having a truncated cone-shape and being revolvable around the sun gear and rotatable about its axis; a carrier for connecting the planet rollers with each other; a movable ring disposed to be circumscribed on outer tangential line of the planet rollers and movable by moving member along a longitudinal direction of the planet rollers to change a rotational speed of the planet rollers by varying an operating diameter so that an output speed outputted through the carriers connecting the planet roller with each other can be varied; and a second speed changing mechanism for changing the output speed from the speed changin

Abstract: An Fe-Mn vibration damping alloy steel having a mixture structure of .epsilon., .alpha.' and .gamma.. The alloy steel consists of iron, manganese from 10 to 24% by weight and limited amounts of impurities. The alloy steel is manufactured by preparing an ingot at a temperature of 1000.degree. C. to 1300.degree. C. for 12 to 40 hours to homogenize the ingot and hot-rolling the homogenized ingot to produce a rolled alloy bar or plate, performing solid solution treatment on the alloy steel at 900.degree. C. to 1100.degree. C. for 30 to 60 minutes, cooling the alloy steel by air or water, and cold rolling the alloy steel at a reduction rate of greater than 0% and below 30% at around room temperature.