Well tool which changes reciprocating movement to rotary motion

A well tool comprising:

• a. a tubular housing connectable in fluid communication with the lower end of a pipe string;
• b. a piston assembly carried by said housing for relative reciprocal movement therein between first and second terminal positions in response to fluid pressure communicated to said housing through said pipe string, said piston assembly sealingly engaging said housing and defining at least one annular chamber therebetween;
• c. a working member carried by said housing for movement between first and second terminal positions in response to said reciprocal movement of said piston assembly;
• and
• d. valve means carried by said housing blocking fluid communication between said pipe string and a portion of said piston assembly, when said piston assembly is in said first terminal position, but responsive to predetermined movement of said piston assembly toward said second terminal position to open and permit fluid communication with said portion of said piston assembly for returning said piston assembly to said first terminal position;
• e. in which said piston assembly includes an annular surface within said annular chamber against which the pressure within said pipe string acts to force said piston assembly toward said first terminal position when said valve means is opened.

A well tool comprising:

• a. a tubular housing connectable in fluid communication with the lower end of a pipe string;
• b. a piston assembly carried by said housing for relative axial movement therein from a first to a second terminal position in response to fluid pressure communicated through said pipe string to a first pressure area on said piston assembly;
• c. valve means carried by said housing movable from a closed position to an open position, in response to predetermined axial movement of said piston assembly, to permit said fluid pressure to be communicated to a second pressure area on said piston assembly oppositely directed from said first pressure area and forcing said piston assembly to return to said first terminal position;
• d. a working member carried by said housing for movement in response to a reciprocal movement of said piston assembly;
• and
• e. retainer means cooperative between said valve means and said piston assembly to retain said valve means in said closed position when said piston assembly is in said first terminal position, but releaseable responsive to predetermined movement of said piston assembly toward said second terminal position to permit movement of said valve means to said open position.