A multiple watt-linkage force transfer mechanism is provided for an internal-combustion engine. The force transfer mechanism comprises two "bell cranks" that are used to drive a single crankshaft through a watt linkage mechanism. Each bell crank, in turn, is driven by two pistons through corresponding watt linkage mechanisms. The watt linkages connected to the pistons enable the connection ends of the pistons to travel along substantially straight paths, significantly reducing side loads against the piston walls. Also, all four pistons preferably drive a single connecting rod. This changes the role of the crankshaft--and the corresponding strength and rigidity requirements for the crankshaft--by reducing the necessary number of rod journals and main journals on the crankshaft.