a compressed fluid motor has a plurality of cylinders with a piston and a piston rod . a main bearing is concentric with a crankpin and coupled to a shaft . compressed fluid on the piston pushes on the main bearing via its corresponding piston rod . bearing guide plates hold the one or more piston rod in place on the main bearing . a timing and control mechanism controls flow of compressible fluid to press on the piston and turn the shaft to perform work .