Complex sentence: The powerplant, a compound steam engine with cylinder bores of 3 and 6 inches and a stroke of 6 inches, was capable of developing 12 bhp at 150 psi or 15 bhp at 300; side-train drive was used to transmit power to the wheels.
Split into simpler sentences: The powerplant, a compound steam engine with cylinder bores of 3 and 6 inches and a stroke of 6 inches, was capable of developing 12 bhp at 150 psi or 15 bhp at 300. Side-train drive was used to transmit power to the wheels.