A cycle starts with the piston–plunger combination in the bottom dead centre: most to the right. The electronic control opens the frequency control valve. This increases the pressure in the compressure cylinder, moving the piston-plunger to the left. Simultaneously, air is compressed in the combustion cylinder and oil is sucked into the power cylinder.
When the piston-plunger arrives in the top dead centre fuel is injected and ignites. The expanding gases will force the piston plunger to move back to the bottom dead centre. Oil is pumped to the high pressure side.
The burned gases are replaced by fresh air due to the loop scavenging process. In the bottom dead centre the piston-plunger will wait until the electronic control gives a new starting signal to the frequency control valve.