Impact devices

Abstract

A pair of rotating flywheels which engage a ram for moving a tool which impacts a part, such as a nail to be driven, are rotated in opposite directions from a single motor or other rotating means, through a pair of substantially identical gears, one of which drives one flywheel and the other of which drives the other flywheel. The drive connection between the respective gears and each of the flywheels may include a belt and pulley arrangement, so that each flywheel may be driven directly by the respective belt but the flywheels are pivoted toward and away from the ram so that when the flywheel moves toward the corresponding side of the ram, the connection between the belt and the corresponding pulley will tend to slacken. A special flywheel pulley has an inner V-shaped groove and parallel side walls for guiding the belt into the groove when full tension occurs. A pair of sockets for receiving pivot pins for the respective flywheels are connected by a bar which is integral with a corresponding end plate and not only withstand precession forces but also tensile forces. A friction surface on the ram, particularly when the flywheel peripheries are polished steel, is a fabric layer of natural fiber, such as long fiber cotton cloth, impregnated by and molded in polyurethane, i.e. a natural fiber embedded in a medium hard plastic or rubber. A bumper has a pyramidal socket to engage a corresponding end of the ram on its return.