Engine using compressed air

An engine driven by a compressed air, comprising:

• means for generating compressed air
• an intake manifold connected with an outlet of said means;
• a cylinder block including a plurality of cylinders communicating with the intake manifold;
• a crank shaft connected to a piston in the cylinder via a connecting rod, wherein the crank shaft have first, second, third, and fourth crank pins each of which is connected to the corresponding connecting rod, and wherein the first and fourth crank pins are oppositely disposed, the second and third crank pins oppositely disposed, and an angle between the first and second crank pins is a right angle;
• a cam shaft comprising intake and exhaust cams;
• and
• power transmitting means between the cam shaft and the crank shaft.