Rotatable shaft with fluid actuated lock piston

1. A system comprising:

a lock housing having an internal region;

a rotatable shaft having a coupling bore extending into the internal region of the lock housing;

a pressure chamber formed within the internal region of the lock housing;

a lock piston positioned within the pressure chamber, the lock piston operable for selectively locking the rotatable shaft; and

a fluid pump in fluid communication with the pressure chamber;

wherein the rotatable shaft includes a plurality of key splines protruding radially outward around an outer circumferential wall.

2. The system of claim 1 , wherein the lock piston is engaged about a portion of the rotatable shaft.

3. The system of claim 1 , wherein the lock piston is moveable between first and second positions; and

wherein the rotatable shaft is locked when the piston is in the first position and unlocked when the piston is in the second position.

4. The system of claim 3 further comprising a resilient member engageable with the lock piston to urge the lock piston toward the first position.

5. The system of claim 3 , wherein pressurized fluid is discharged from the pump into the pressure chamber such that a net hydraulic force causes the lock piston to move from the first position to the second position.

6. The system of claim 1 further comprising:

a bearing housing positioned adjacent the lock housing; and

a bearing assembly located within the bearing housing configured to rotatably support the rotatable shaft.

7. The system of claim 6 further comprising a plurality guide pins extending from a side wall of the bearing housing.

8. The system of claim 7 , wherein lock piston includes:

a cylindrical bore engaged around the coupling bore of the shaft;

a plurality of lugs extending radially outward from the cylindrical bore, each lug having an outer perimeter wall with an opposing first face and second face extending between the outer perimeter wall and the cylindrical bore; and

a guide slot formed between each adjacent pair of lugs.

9. The system of claim 8 , wherein each of the guide pins of the bearing housing slidingly engage within a corresponding guide slot of the lock piston as the lock piston moves between first and second positions.

10. The system of claim 1 , further comprising a motor operably coupled to the rotatable shaft.

11. The system of claim 1 , wherein the lock piston includes a plurality of grooves formed on an inner circumferential wall, each groove configured to slidingly receive a corresponding key spline when the lock piston is in a locked position.

12. A method comprising:

inserting a rotatable shaft within a lock housing;

rotatably supporting the rotatable shaft in a bearing housing adjacent the lock housing;

positioning a lock piston around a portion of the rotatable shaft within a pressure chamber located within the lock housing, the lock piston movable between first and second positions within the pressure chamber such that the lock piston engages and disengages a guide pin that extends from a side wall of the bearing housing;

pumping pressurized fluid into the pressure chamber; and

moving the lock piston from the first position to the second position in response to the pumping of the pressurized fluid into the pressure chamber.

13. The method of claim 12 further comprising:

locking the rotatable shaft when the lock piston is in the first position; and

unlocking the rotatable shaft when the lock piston is in a second position.

14. The method of claim 12 further comprising moving the lock piston from the second position to the first position with a resilient member when the pressure chamber is depressurized.

15. The method of claim 12 , rotating the rotatable shaft with a motor when the lock piston is the second position.

16. An apparatus comprising:

a motor coupled to a rotatable shaft;

a bearing housing having a bearing assembly configured to rotatably support the rotatable shaft;

a lock housing connected to the bearing housing;

a pressure chamber formed within the lock housing;

a source of pressurized fluid in fluid communication with the pressure chamber;

a lock piston positioned within the pressure chamber, the lock piston configured to move to from a first position to a second position when pressurized fluid is pumped into the pressure chamber; and

a plurality of guide pins extending from the bearing housing into the pressure chamber of the lock housing.

17. The apparatus of claim 16 further comprising a fluid pump operable for pumping pressurized fluid into the pressure chamber.

18. The apparatus of claim 16 further comprising a resilient member operable for urging the lock piston toward the first position when the pressure chamber is depressurized.

19. The apparatus of claim 16 , wherein the lock piston further comprises:

a piston bore configured to receive a portion of the rotatable shaft internally thereto;

a plurality of lugs extending radially outward from the piston bore; and

a guide slot formed between each adjacent pair of lugs.

20. The apparatus of claim 19 , wherein each guide slot slidingly engages along a length of a corresponding pin when the lock housing moves between locked and unlocked positions.

21. The apparatus of claim 16 , wherein the rotatable shaft includes a plurality of key splines positioned about an outer circumferential wall.

22. The apparatus of claim 21 , wherein the lock piston includes a plurality of internal grooves formed within the piston bore configured to slidingly receive the key splines when the lock piston is moved from the second position to the first position.

23. The apparatus of claim 16 , wherein the motor is a hydraulic motor in fluid communication with the pressure chamber.