Device for converting between rotary and rectilinear motion

A device for converting linear motion to rotary motion or vice versa, comprising a rotatable crank, having a crankpin and a bearing element rotatably mounted on said crankpin, and a slide mounted for reciprocating linear movement, said slide including a first arcuate bearing surface located on one side of said crankpin in continuous engagement with said bearing element as said bearing element moves back and forth along said first arcuate bearing surface and a second arcuate bearing surface located on an opposite side of said crankpin in continuous engagement with said bearing element as said bearing element moves back and forth along said second arcuate bearing surface, said second arcuate bearing surface being rotatable in response to the rotation of said bearing element, whereby the linear motion of said slide is continuously converted into the rotary motion of said crank or vice versa.