In the third working chamber, there is formed {TAIL ~ an oscillating column} of {HEAD ~ the working medium}, which presses against the inner sides of both pistons 
In the third working chamber , there is formed { TAIL ~ an oscillating column } of { HEAD ~ the working medium } , which presses against the inner sides of both pistons
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH