1. IN COMBINATION, FIRST AND SECOND CYLINDER UNITS, EACH CYLINDER UNIT COMPRISING, A BASE CYLINDER HAVING AN OPEN TOP AND A CLOSED BOTTOM PORTION, A SHAFT MEANS RIGIDLY SECURED TO THE BOTTOM PORTION OF SAID BASE CYLINDER AND EXTENDING UPWARDLY AND OUTWARDLY FROM THE UPPER END THEREOF, A MOVABLE CYLINDER SLIDABLY MOUNTED ON SAID SHAFT MEANS AND HAVING AT LEAST ONE OF ITS ENDS SLIDABLY MOUNTED WITHIN SAID BASE CYLINDER, A PISTON ELEMENT RIGIDLY SECURED TO SAID SHAFT WITHIN SAID MOVABLE CYLINDER TO FORM SEPARATE FLUID COMPARTMENTS WITHIN SAID MOVABLE CYLINDER ABOVE AND BELOW SAID PISTON ELEMENT, A FIRST CONDUIT CONNECTING THE COMPARTMENT ABOVE SAID PISTON IN SAID FIRST CYLINDER UNIT TO THE COMPARTMENT BELOW SAID PISTON IN SAID SECOND CYLINDER UNIT, A SECOND CONDUIT CONNECTING THE COMPARTMENT BELOW SAID PISTON IN SAID FIRST UNIT WITH THE COMPARTMENT ABOVE SAID PISTON IN SAID SECOND CYLINDER UNIT, A HYDRAULIC POWER MEANS IN COMMUNICATION WITH SAID FIRST AND SECOND CONDUITS, A VALVE MEANS IMPOSED IN SAID CONDUITS TO CONTROL THE FLOW OF FLUID THROUGH SAID CONDUITS TOWARDS OR AWAY SAID COMPARTMENTS AT DIFFERENT TIMES BY SAID HYDRAULIC POWER MEANS, AND AN ACTUATING MEANS ON SAID VALVE MEANS AND IN THE MOVABLE PATH OF ONE OF SAID MOVABLE CYLINDERS WHEREUPON THE MOVEMENT OF SID ONE MOVABLE CYLINDER WILL ENGAGE SAID ACTUATING MEANS TO OPERATE SAID VALVE MEANS.