Patent ID: 8584765

Claim:
Apparatus useful for preventing the premature setting of upper slips of a downhole tool in a well bore prior to reaching the desired setting location in the well bore and assisting in setting the upper slips in the well bore, the downhole tool having a main body and upper and lower ends, the apparatus comprising: at least one locking mechanism movable radially inwardly relative to the main body of the downhole tool from at least a first position to at least a second position, said at least one locking mechanism in said first position configured to prevent the upper slips from engaging the well bore wall before being positioned at the desired setting location in the well bore and in said second position, said at least one locking mechanism allowing the upper slips to be moved into engagement with the well bore wall; a sleeve axially moveable relative to the main body of the downhole tool in the direction of the lower end of the downhole tool and configured to move said at least one locking mechanism from said first position to said second position as said sleeve moves axially toward the lower end of the downhole tool, said sleeve also being configured to move the upper slips axially relative to the main body of the downhole tool as said sleeve moves axially toward the lower end of the downhole tool to engage the upper slips with the well bore wall; and an upper ring disposed around the main body of the downhole tool between said at least one locking mechanism and the upper slips, said upper ring being configured to push the upper slips axially relative to the main body of the downhole tool in the direction of the lower end thereof into engagement with the well bore wall, said at least one locking mechanism including at least one collet finger engaged with said upper ring in said first position of said locking mechanism and disengaged from said upper ring in said second position of said locking mechanism, wherein said sleeve is configured to bias said at least one collet finger radially inwardly to disengage said collet finger from said upper ring as said sleeve moves axially toward the lower end of the downhole tool.