US Patent 7766088 System and method for actuating wellbore tools

An actuator operatively coupled to a wellbore tool is activated upon receiving fluid that a predetermined applied pressure. When the fluid string reaches the predetermined applied pressure, the actuator undertakes a specified action such as longitudinal movement, rotation, expansion, etc. that actuates or operates the wellbore tool. Premature actuation of the wellbore tool is prevented by applying a resistive force to the actuator that, alone or in cooperation with another mechanism, arrests movement of the actuator. This resistive force is generated by applied pressure of the fluid in the work string.