The displacing piston remains at its lower resting position and hinders contact with the warm cylinder wall, while the working piston compresses the gas.
The working piston remains at its lower resting position and the displacing piston is forced upwards, whereby it shifts the gas from the cold temperature reservoir to the underlying warm temperature reservoir.
While the displacing piston remains at its upper resting position, the gas expands in the warmer underside and the working piston moves upwards.
The displacing piston moves down, while the working piston is at its upper resting position. The gas is forced upwards and comes in contact with the colder upper side of the aperture, whereupon it cools and shrinks.