Patent ID: 8813603

Claim:
A crank drive comprising: a crankshaft having main journals defining a crankshaft axis, a plurality of crank pins each having a bearing surface with a concavely curved region in a longitudinal crankshaft section, and webs extending radially from the crankshaft axis and connecting the crank pins to the main journals, the concavely curved region of each crank pin having a continuous concave curvature that extends into a sidewall section of the webs and defines a bearing surface; and respective conrods each having a big end fitted to a respective one of the crank pins and having a bearing surface with a convexly shaped region symmetrical to a middle of the respective crank pin bearing surface and in contact with the concave region of the bearing surface of the respective crank pin in a load-bearing area that transmits forces acting between the big end of the respective conrod and the crank pin when the drive is in use, shapes of the bearing surfaces being in accordance with the principle of uniformly distributed stresses such that essentially the same stress is distributed overall in the bearing surfaces in time average.