Abstract: A tappet assembly for use in the valve train of an automotive type internal combustion engine has a roller at one end adapted to be engaged by the cam lobe of a camshaft for that engine. A spring biased piston is incorporated in the assembly for movement into frictional engagement with the roller at low engine speeds to dampen out vibrational or shaking forces present in the engine at this speed level by increasing the resistance to rotation of the roller. At higher engine speeds, the piston is moved progressively away from frictional contact with the roller by engine oil galley oil pressure, which increases with engine speed, to a point where the piston is completely removed from engagement with the roller and the roller is permitted to freely rotate at a point when the engine vibration or shaking forces are no longer present.

Abstract: A driveshaft for a motor vehicle having a double tapered tubular body with its largest diameter near its midpoint and its least diameter adjacent its opposite ends. The body is substantially and continuously tapered from the midpoint to each of the ends. The tapered section of the tubular body has its outer surface positioned near a surface defined by a parabola revolved about the longitudinal axis of the body. The parabola has its apex at the midpoint of the driveshaft and intersects two points on the longitudinal axis at approximately the mounting planes where the driveshaft is supported at its ends. In addition, a method of manufacturing the tapered tubular body of the driveshaft includes a mold having a tapered wall section and cylindrical shaped end sections to receive the cylindrical tube. The cylindrical tube is able to receive varying lengths of elastomeric plugs which can be sequentially compressed to deform the tube outwardly to abut the tapered wall section of the mold.