A pressure-balanced separation-nut device for releasably engaging a threaded element coaxial with the linear axis of the device which comprises:
- a housing forming an internal cavity,
- said internal cavity including first, second, third and fourth sections each of lesser diameter in successive order progressing toward the forward end of said housing, said fourth section forming an open end in said housing;
- a base secured to the back end of said first section of said housing;
- said base including an axial aperture therein;
- a seat member secured to said base member coaxial therewith, extending into said cavity, and having an aperture with substantially the same diameter as the aperture in said base member;
- a segmented threaded nut within said first section of said cavity juxtaposed said seat member and coaxial with said cavity in said housing;
- a piston cylinder encircling said segmented nut;
- said piston cylinder including an axially extending cylindrical portion and first and second transverse annular end walls extending radially inward, the second wall being forward of the first wall;
- a piston ring secured to one end of said axially extending cylindrical portion of said piston cylinder between the inner surface of said piston cylinder and the outer surface of said segmented nut to form a locking means for said nut segments;
- said piston ring locking said segmented nut in place to receive said threaded element;
- a buffer piston including a piston head and a piston rod extending forward from said piston head with an axial aperture extending through said buffer piston and having a transverse aperture across its diameter near said piston head and opposite said first transverse annular wall of said piston cylinder;
- said piston head positioned within said piston cylinder between said nut segments and said first transverse annular wall of said piston cylinder, said piston head having an outside diameter substantially equal to the inside diameter of said piston cylinder with a face contoured to that of said segmented nut adjacent thereto;
- said piston rod extending through said second transverse annular wall of said piston cylinder and secured within said third cavity section of said housing coaxial therewith;
- a space bounded by said piston rod, said piston cylinder, said second transverse wall of said piston cylinder and said buffer-piston head, said transverse aperture connecting with said space;
- an ejecting rod coaxially positioned within said aperture in said buffer piston for relative movement therein for ejection of said threaded element, said ejecting rod having a head at the end thereof remote from said buffer-piston head;
- an end-closure means within said fourth cavity section of said housing and positioned between said ejection rod and said open end in said housing, said end-closure means comprising a piston exposed to the surrounding medium, means for permitting axial movement of said end-closure means within said housing prior to and during release of the threaded element;
- sealing means to prevent leakage between said buffer piston and said piston cylinder, between said piston head and said ejection rod, between said piston rod and said housing, and between said end-closure means and said housing;
- at least one opening in said housing for reception of a fluid source, said opening being located between said end-closure means and said piston rod;
- a fluid confined within the space between said buffer-piston head and said first radially extending wall of said piston cylinder, inside said aperture in said buffer-piston rod, between said ejection rod and said buffer-piston cylinder, and between said ejection rod head, said end-closure means, and a fluidpressure generating means,
- said fluid-pressure generating means for increasing fluid pressure within said housing to force said piston cylinder and said locking piston ring from their locking position to an unlocked position;
- and
- whereby pressure of the surrounding medium is applied to said end-closure piston which applies pressure to said confined fluid to balance pressures on said piston cylinder created by free flooding of said housing.