Patent ID: 8899313

Claim:
A cutting unit for a hydro-mechanical slot-type perforator having an axis, said cutting unit is mounted in a casing, the casing having an edge with an edge's shape; said cutting unit is associated with and driven by a piston capable of moving in the casing; said cutting unit comprises: a first holder immovable relative to the piston; a second holder immovable relative to the casing; the first and the second holders are such configured to provide an interaction with each other during movements of the piston; the second holder includes a recess having a recess' shape capable of cooperation with the edge's shape, thereby providing for fixation of the second holder in the casing absent of pressure applied to the piston during the interaction of the first holder and the second holder; cutting tools mounted substantially on the first holder and on the second holder; said cutting tools are such configured to provide extending from the axis in opposite directions and retracting thereto during movements of the piston; and a retractable mechanism for bringing said cutting unit into a transportation position and fixing said cutting unit therein; said retractable mechanism including: at least one guide groove made in the second holder, and at least one connecting rod attached to the first holder; and wherein said connecting rod is configured to move through the groove, thereby ensuring a return of the second holder into said transportation position during a reverse movement of the piston.