Abstract: A silent chain power transmitting apparatus includes a silent chain and two or more sprockets with different number of teeth, wherein the sprockets each have a tooth form formed by hobbing with a hob cutter having teeth profiled similarly with the profile of a series of trapezoidal teeth formed by the inside flanks of longitudinally overlapping link plates of the silent chain so as to cut the periphery of a cylindrical workpiece with an amount of addendum modification set in such a manner that an engagement height of the inside flank at the onset of the meshing engagement between the silent chain and the sprocket is in equal to the distance between the sprocket center and the connecting pin centers when the silent chain is wrapped around and seated on the sprocket. The outside flanks of the silent chain have a first portion profiled by an envelope that is tangent to every one of a group of tooth forms of the sprockets when the silent chain is wrapped around the sprockets with different numbers of teeth.

Abstract: An oscillatory drive unit for use in an oscillating system to be oscillated substantially at the resonance point of the oscillating system, wherein the oscillating system includes a mass to be oscillated and a countermass to which the mass is connected by resilient coupling members. The oscillatory drive unit includes a piston-cylinder-component that is operatively connected to the mass and the countermass. The piston-cylinder-component includes a cylinder chamber and a piston. The piston is arranged for reciprocal movement between a first end position and a second end position. Gas is introduced under pressure into the cylinder chamber within an energizing range of piston positions defined by a first energizing position and a second energizing position of the piston, and gas is vented from the chamber within a venting range of piston positions defined by a first venting position and a second venting position of the piston.