136446 ⎘
Reciprocating-piston machines or engines without rotary main shaft, e.g. of free-piston type in which the movement in the two directions is obtained by one double acting piston motor one side of the double acting piston motor being always under the influence of the fluid under pressure the fluid under pressure being continuously delivered to one motor chamber and reacting the other chamber through a valve located in the piston, to bring the piston back in its start-position