biases piston 48 and actuator pin to the right as seen in fig4 upon pressurization of chamber 50 by the pump pin 46 is retracted into cylinder 38 forward of cylinder 38 as viewed in fig3 is a pivot rod 56 extending through parallel plates 24 and having fixed at each end a hook 30 hooks 30 are faced against the outside surface of a parallel plates 24 and are rotatable about the axis of pivot rod 56 hook 30 forms a generally circular aperture with notch 23 when hook 30 is in the closed position shown in fig3 projecting rearwardly from hook 30 is a hook finger 58 which engages actuator pin 46 to prevent hook 30 from swinging counterclockwise under the influence of gravity hooks 30 may be detachably fastened to pivot rod 56 by a threaded fasteners 25 screwed through hook 30 to bear against a flat surface at the end of pivot rod 56 also shown in fig3 is a connector beam 60 connected to a conventional mine roller assembly such as that described in conjunction with fig1 and 2 at the end of connector beam 60 are two transverse pins 28 each of which fits into one of notches 23 when connector beam 60 is inserted between parallel plates 24 operation of my connection mechanism shown in fig3 is relatively simple to release the mine roller assembly from tank 6 a crew member inside tank 6 actuates a pump to pressurize chamber 50 and retract actuator pin 46 into cylinder 38 hook.