Safety holding valve rod eye assembly

Claim 1

In a double-acting hydraulic cylinder and piston unit comprising a cylinder, a piston, and a piston rod in which the hydraulic fluid is supplied to both sides of said piston through the piston rod, an improved rod eye assembly comprising, a rod eye body attached to one end of said piston rod and having first and second sides, a fluid passageway in each side of the rod eye body, each of said passageways having an external port in its respective rod eye body side and an internal port for communication with the interior of said piston rod for conveying actuating fluid to and from said unit, swivel joint means at each of said external ports for conveying actuating fluid to and from the respective passageways and for rotatably supporting said one end of said piston rod, safety valve means in at least one of said passageways for sealing said one passageway in a fluid-tight manner when no pressure of greater than a first predetermined amount is exerted on the safety valve means from the external port of said one passageway, and no pressure of greater than a second predetermined amount is exerted on said safety valve means from either of (a) the internal port of said one passageway and (b) the other of said passageway, the other of said passageways being in fluid contact with said safety valve means, said second predetermined pressure being greater than the first predetermined pressure, said safety valve means further including, first and second conduit means connecting said external and internal ports of said one passageway in fluid communication, first, normally closed, sealing means in said first conduit means for opening said first conduit means when subjected to a pressure of greater than said first predetermined amount on the side of the first sealing means closest to the external port of said one passageway, said first sealing means further including, an annular seat in said passage, a ball closure member spring biased into first engagement with said annular seat with said predetermined amount of pressure, the ball being located between the annular seat and the internal port of said one passageway, second, normally closed, sealing means in said second conduit means for opening said second conduit means when subjected to a pressure of greater than said second predetermined amount on the side of the second sealing means closest to the internal port of said one passageway, said second sealing means further including, a cylindrical spool slidable within said one passageway and being of a smaller diameter than said one passageway, said first conduit means being defined as a passage extending through said spool, the second conduit means being defined as an annulus formed between the spool and said one passageway, an annular flange on said spool, an annular flange in said one passageway between the flange on the spool and the internal port, for contacting the flange on said spool in sealing engagement, spring means for forcing the flange on the spool into contact with the passageway flange with said second predetermined amount of pressure, means on the safety valve means for opening the second, normally closed, sealing means in response to pressure in the other of said passageways in excess of a third predetermined amount, and manually operated cam means partially extending into said one passageway for moving the flange on the spool against the force exerted by said spring means and out of contact with the passageway flange.