ACTUATOR ASSEMBLIES

1 . An actuator assembly, comprising:

a casing having an elongated body defining an interior with a longitudinal axis and an open end providing access to the interior;

a main piston having at least a portion slidably received within the interior through the open end for sliding axial movement relative to the longitudinal axis between a retracted position and an extended position; and

a locking mechanism selectively prohibiting reciprocation of the main piston relative to the casing, comprising:

at least one moveable lock segment mounted within a portion of the main piston such that sliding movement of the at least one moveable lock segment moves the at least one moveable lock segment radially, relative to the longitudinal axis, between a locked position and an unlocked position, where in the locked position a portion of the at least one moveable lock segment extends from the portion of the main piston into sliding interference with the casing preventing the main piston from reciprocating relative to the casing and an unlocked position where the main piston may reciprocate relative to the casing;

a lock piston slidable relative to the longitudinal axis between an actuated position where the at least one moveable lock segment is in the locked position and a non-actuated position, where the at least one moveable lock segment is in the unlocked position; and

a pilot piston adjacent the lock piston and moveable between a first position and a second position, where the pilot piston moves the lock piston to the non-actuated position.

2 . The actuator assembly of claim 1 wherein the casing comprises at least one port configured to provide hydraulic pressure to move the pilot piston from the first position to the second position.

3 . The actuator assembly of claim 2 wherein the casing comprises a secondary port configured to provide additional hydraulic pressure configured to move the main piston towards the extended position.

4 . The actuator assembly of claim 1 , further comprising a biasing element configured to bias the pilot piston into the second position.

5 . The actuator assembly of claim 1 , further comprising a lockout mechanism configured to selectively engage the lock piston to prevent the lock piston from moving to the non-actuated position.

6 . The actuator assembly of claim 5 wherein the lockout mechanism comprises a moveable bar selectively receivable within a recess of the lock piston.

7 . The actuator assembly of claim 1 wherein the locking mechanism comprises a biasing mechanism configured to bias the lock piston towards the locked position.

8 . The actuator assembly of claim 7 wherein the biasing mechanism comprises multiple springs biasing the lock piston towards the locked position.

9 . The actuator assembly of claim 1 wherein the locking mechanism comprises multiple moveable lock segments.

10 . The actuator assembly of claim 9 wherein the multiple moveable lock segments are radially spaced around the lock piston.

11 . An actuator assembly comprising:

a casing having an elongated body defining an interior with a longitudinal axis and an open end providing access to the interior;

a main piston having at least a portion slidably received within the interior through the open end for sliding axial movement relative to the longitudinal axis between a retracted position and an extended position;

a lock segment slidably mounted to a portion of the main piston such that sliding movement of the lock segment moves the lock segment radially, relative to the longitudinal axis, between locked and unlocked positions; and

a lock segment actuator slidable relative to the longitudinal axis between an actuated position and a non-actuated position;

wherein the sliding movement of the lock segment actuator to the actuated position slidably moves the lock segment to the locked position where a portion of the lock segment extends from the portion of the main piston into sliding interference with the casing and the lock segment abuts a portion of the lock segment actuator to define a contact interface such that only radial forces are transferred through the contact interface.

12 . The actuator assembly of claim 11 wherein the contact interface is defined by a zero degree interface between the lock segment and the portion of the lock segment actuator.

13 . The actuator assembly of claim 11 , further comprising a pilot piston adjacent the lock segment actuator and moveable between a first position and a second position, where the pilot piston moves the lock segment actuator to the non-actuated position.

14 . An actuator assembly comprising:

a casing having an elongated body defining an interior with a longitudinal axis and an open end providing access to the interior;

a main piston having at least a portion slidably received within the interior through the open end for sliding axial movement relative to the longitudinal axis between a retracted position and an extended position;

a lock segment slidably mounted to a portion of the main piston such that the sliding movement of the lock segment moves the lock segment radially, relative to the longitudinal axis, between locked and unlocked positions;

a lock segment actuator having a lock piston slidable relative to the longitudinal axis between an actuated position and non-actuated position; and

wherein the sliding of the lock piston to the actuated position slides the lock segment to the locked position, where a portion of the lock segment extends from the portion of the main piston into sliding interference with the casing and the lock segment abuts a portion of the lock piston, and the lock piston is pressure balanced.

15 . The actuator assembly of claim 14 , further comprising a pilot piston adjacent the lock piston and moveable between a first position and a second position, where the pilot piston moves the lock piston to the non-actuated position.