Stirling cycle machine

An external combustion engine comprising:

• a burner element;
• at least two heater heads defining a working space;
• at least two pistons;
• a cooler;
• a crankcase comprising:
• a crankshaft for producing an engine output;
• two piston rods each connected at a proximal end of the piston rod to one of the at least two pistons;
• a rocking beam rotating about a fixed rocker pivot for driving the crankshaft, the rocking beam including two end pivots and a connecting pivot, wherein the two end pivots and the connecting pivot are in a single plane and equidistant from the rocker pivot, the connecting pivot is separate from either end pivot, and the rocking beam drives the two piston rods via the two end pivots;
• two link rods, each link rod connected at a proximal end of the link rod to one of the two piston rods at a distal end of the piston rod and to one of the two end pivots at a distal end of the link rod, the length of each link rod being not greater than a distance from one of the two end pivots to the rocker pivot;
• and
• a connecting rod located on the side of the rocking beam that is opposite from the at least two pistons and connected at a first end to the connecting pivot of the rocking beam and at a second end to the crankshaft to convert rotary motion of the rocking beam to rotary motion of the crankshaft wherein the at least two pistons reciprocate along substantially linear piston axes in the crankcase and the crankshaft is arranged on the side of the rocking beam that is opposite from the at least two pistons.