US Patent 7797841 Drive mechanism for a reciprocating saw

Embodiments of a reciprocating drive apparatus are disclosed which comprise a housing, a drive shaft rotatably mounted in the housing, an elongated plunger mounted in the housing for reciprocating motion; the plunger having a rear end portion configured to engage a wobble plate interface structure and a front end portion for attaching a tool, a first bushing positioned in the housing for retaining the front end portion in a manner whereby the plunger is not restrained from rotating about a first axis of rotation, a second bushing positioned in the housing for receiving the rear end portion of the elongated plunger in a manner whereby the plunger is not restrained from rotating along a second axis of rotation as the plunger reciprocates in the bushing, a wobble plate assembly operatively connected to the drive shaft and having an elongated arm with a wobble plate interface structure for engaging the rear end portion of the plunger and reciprocating the plunger in the first and second bushings.