An engine designed by engineers at Sanderson Engine Development LLC, Upton, Mass., uses a U-joint that replaces the crankshaft and connecting rods.
The U-joint lets a transition arm oscillate in a controlled wobble while keeping the output shaft spinning smoothly. And although the engine is powered by pistons and cylinders similar to those in automotive engines, it can also use cylinders containing two end-to-end pistons for higher power densities.
The company claims that without the crankshaft and connecting rods, the engine is almost perfectly balanced, reducing bearing loads to a minimum. Without the side loading common to traditional combustion engines, the Sanderson engine improves mechanical efficiency by 5 to 8%, as demonstrated in tests, according to its inventors. The company also claims a threefold increase in power-to-weight over traditional diesel engines, and that the engine can be run in reverse as a pump.