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A locking hydraulic actuator has a cylinder and a main piston that is movable from an extend position to a retract position by a hydraulic circuit. The actuator has a locking mechanism that includes a lock piston that slides within a lock piston bore of the main piston. One or more lock segments are

A locking hydraulic actuator has a cylinder and a main piston that is movable from an extend position to a retract position by a hydraulic circuit. The actuator has a locking mechanism that includes a lock piston that slides within a lock piston bore of the main piston. One or more lock segments are held by slots within the main piston and may be radially constrained within a tailstock housing and cylinder. The lock segments maintain the main piston in a locked position. The lock segments have two straight tapers, one on a proximal face and the other on a distal face, which transmit axial loading forces to and from the cylinder and main piston by distributed loading, thereby avoiding point-contact loading and material deformation. The lock piston, lock segments, piston, and cylinder may have different hardnesses.

대표청구항 ▼

1. A locking hydraulic actuator comprising:a cylinder having an inner radial surface, a longitudinal axis, and a cylinder stop surface;a main piston slidingly disposed within said cylinder and having a lock piston bore, said main piston having one or more slots therethrough disposed from an outer ra

1. A locking hydraulic actuator comprising:a cylinder having an inner radial surface, a longitudinal axis, and a cylinder stop surface;a main piston slidingly disposed within said cylinder and having a lock piston bore, said main piston having one or more slots therethrough disposed from an outer radial surface to said lock piston bore, wherein said main piston is movable along said longitudinal axis;a lock piston slidably disposed within said lock piston bore from a first position to a second position in either direction along said longitudinal axis, said lock piston having a first section with a first diameter, and a second section with a second diameter greater than said first diameter;an elastic coupler connecting said main piston to said lock piston, wherein said elastic coupler preloads said lock piston in one direction; andone or more lock segments disposed within said one or more slots and having a proximal straight taper and a distal straight taper and a cylinder-abutting surface, each of said one or more lock segments having an outer radial surface and an inner radial surface, a first and a second lateral face, and a proximal face and a distal face, said one or more lock segments being radially moveable from a locked position wherein each of said cylinder-abutting faces contacts said cylinder stop surface and wherein said main piston is immovable along said longitudinal axis to an unlocked position, wherein said one or more lock segments transfer forces between said piston and said cylinder by distributed loading. 2. The locking hydraulic actuator of claim 1, further comprising a tailstock housing connected to said cylinder. 3. The locking hydraulic actuator of claim 2, further comprising a hydraulic circuit operable to supply and receive hydraulic fluid to and from said cylinder to move said main piston relative to said cylinder. 4. The locking hydraulic actuator of claim 3, wherein said hydraulic circuit comprises a first hydraulic port and a second hydraulic port in said cylinder. 5. The locking hydraulic actuator of claim 1, wherein in said locked position said cylinder-abutting surface contacts said stop surface, and wherein each said inner radial face contacts said second section, each of said proximal tapers contacts a corresponding proximal slot face, and each of said distal tapers contacts a corresponding distal slot face, wherein in said unlocked position each of said inner radial faces contacts said first section. 6. The locking hydraulic actuator of claim 5, wherein said main piston further comprises a main piston head having a main piston head diameter. 7. The locking hydraulic actuator of claim 6, wherein said piston head diameter exceeds said main piston diameter in said cylinder by about 5 mils to about 10 mils. 8. The locking hydraulic actuator of claim 6, wherein a clearance between said each of said one or more lock segments and a corresponding slot is between about one-half mil to about three mils. 9. The locking hydraulic actuator of claim 5, wherein each said proximal straight taper comprises an intersection of two flat faces of said proximal face. 10. The locking hydraulic actuator of claim 5, wherein each said distal straight taper comprises an intersection of two flat faces of said distal face. 11. The locking hydraulic actuator of claim 5, wherein each said proximal straight taper comprises a beveled intersection of two flat faces of said proximal face. 12. The locking hydraulic actuator of claim 5, wherein each said distal straight taper comprises a beveled intersection of two flat faces of said distal face. 13. The locking hydraulic actuator of claim 5, wherein each said proximal straight taper comprises a rounded intersection of two flat faces of said proximal face. 14. The locking hydraulic actuator of claim 5, wherein each said distal straight taper comprises a rounded intersection of two flat faces of said distal face. 15. The locking hydraulic actuator of claim 5, further comprising a lock position indicator mechanism in communication with said lock piston. 16. The locking hydraulic actuator of claim 15, wherein said lock position indicator mechanism comprises:a lock position indicator piston in communication with said lock piston and moveable from a locked position corresponding to said locked position of said lock piston to an unlocked position corresponding to said unlocked position of said lock piston, said lock position indicator piston having a cam surface with a diameter varying from a first diameter to a second diameter larger than said first diameter;a lock position ball in contact with said lock position indicator piston, wherein said lock position indicator ball is disposed within a bore within a tailstock housing and moveable from a first position in said bore to a second position in said bore; anda switch operable to produce a locked signal or an unlocked signal, wherein said switch is in contact with said ball;wherein said switch produces said locked signal in response to said lock position ball moving from said first position to said second position upon force of said cam surface as said lock position indicator piston is moved to said locked position from said unlocked position. 17. The locking hydraulic actuator of claim 16, wherein said switch produces said unlocked signal in response to said lock position ball moving from said second position to said first position as said cam surface moves as said lock position indicator piston is moved from said locked position to said unlocked position. 18. The locking hydraulic actuator of claim 17, further comprising a bias spring tending to force said lock position indicator piston to said unlocked position. 19. The locking hydraulic actuator of claim 18, further comprising a bias spring in said switch tending to force said lock position ball away from said switch. 20. The locking hydraulic actuator of claim 5, wherein said one or more lock segments have a lock segment material hardness, said cylinder has a cylinder material contact surface hardness, and said main piston has a main piston material contact surface hardness, wherein said main piston material contact surface hardness is different from each of said lock segment material hardness and said cylinder material contact surface hardness, and said lock segment hardness is different from said cylinder material contact surface hardness. 21. The locking hydraulic actuator of claim 20, wherein said lock segment material hardness is between about 58 to about 60 on a Rockwell C hardness scale. 22. The locking hydraulic actuator of claim 20, wherein said cylinder material contact surface hardness is between about 52 to about 56 on a Rockwell C hardness scale. 23. The locking hydraulic actuator of claim 20, wherein said lock piston has a lock piston hardness different from each of said lock segment material hardness and said cylinder material contact surface hardness, and said lock segment material hardness is different from said cylinder material contact surface hardness. 24. The locking hydraulic actuator of claim 23, wherein said lock piston hardness is between about 60 to about 65 on a Rockwell C hardness scale. 25. The locking hydraulic actuator of claim 20, wherein said one or more lock segments are made of type AISI S-5 tool steel. 26. The locking hydraulic actuator of claim 20, wherein said lock piston is made of type AISI E52100 steel. 27. The locking actuator of claim 1, wherein said lock piston further comprises an intermediary section with a diameter that varies from said first diameter to said second diameter. 28. The locking hydraulic actuator of claim 1, wherein said diameter of said second section is constant. 29. The locking hydraulic actuator of claim 1, wherein said elastic coupler comprises a spring. 30. In a locking hydraulic actuator of the type in which a main piston is slidably disposed within a cylinder, and wherein said main piston has a main piston diameter and a lock piston slidably disposed within said main piston, and wherein one or more lock segments are radially slidingly disposed within slots in said main piston and radially moveable from a locked position to an unlocked position, wherein the improvement comprises:a proximal straight taper disposed on a proximal face of each lock segment, and a distal straight taper disposed on a distal face of each lock segment, wherein said proximal straight taper transmits and distributes stresses of an axial load developed in said locking hydraulic actuator across said width of said lock segment to said proximal face of said slot, and wherein said distal straight taper transmits and distributes stresses of said axial load developed in said locking hydraulic actuator across said width of said lock segment to said distal face of said slot. 31. The improvement of claim 30, wherein said one or more lock segments have a lock segment material hardness, said cylinder has a cylinder material contact surface hardness, and said main piston has a main piston material contact surface hardness, wherein said main piston material contact surface hardness is different from each of said lock segment material hardness and said cylinder material contact surface hardness, and said lock segment material hardness is different from said cylinder material contact surface hardness. 32. The improvement of claim 30, wherein said main piston has a main piston head having a main piston head diameter in said cylinder that exceeds a diameter of said main piston by about 5 mils to about 10 mils. 33. The locking mechanism of claim 32, wherein a diameter of a piston head exceeds a main piston diameter in said cylinder by about 5 mils to about 10 mils. 34. The locking mechanism of claim 33, further comprising a bias spring tending to force said lock position indicator piston to said unlocked position. 35. The locking mechanism of claim 32, wherein a clearance between said each of said one or more lock segments and a corresponding slot is between about one-half mil to about three mils. 36. The improvement of claim 30, wherein said clearance between said each of said one or more lock segments and a corresponding slot is between about one-half mil to about three mils. 37. A locking mechanism for a piston and cylinder assembly, said locking mechanism comprising:a lock piston slidingly disposed within said piston of said piston and cylinder assembly; andone or more lock segments disposed in one or more corresponding slots disposed through said piston from an outer radial surface to an inner radial surface, said one or more lock segments each having a proximal face having a proximal straight taper, a distal face having a distal straight taper, and a width, said one or more slots each having a proximal face and a distal face, wherein said proximal straight taper transmits and distributes stresses of an axial load developed in said piston and cylinder assembly across said width of said lock segment to said proximal face of said slot, and wherein said distal straight taper transmits and distributes stresses of said axial load developed in said piston and cylinder assembly across said width of said lock segment to said distal face of said slot, and wherein said one or more lock segments, in response to movement of said lock piston, are moveable radially from a locked position wherein said piston is locked within said cylinder to an unlocked position wherein said piston is moveable within said cylinder. 38. The locking mechanism of claim 37, further comprising a lock position indicator mechanism in communication with said lock piston. 39. The locking mechanism of claim 38, wherein said lock position indication mechanism comprises:a lock position indicator piston in communication with said lock piston and moveable from a locked position corresponding to said locked position of said lock piston to an unlocked position corresponding to said unlocked position of said lock piston, said lock position ind icator piston having a cam surface with a diameter varying from a first diameter to a second diameter larger than said first diameter;a lock position ball in contact with said lock position indicator piston, wherein said lock position indicator ball is disposed within a bore within a tailstock housing and moveable from a first position in said bore to a second position in said bore; anda switch operable to produce a locked signal or an unlocked signal, wherein said switch is in contact with said lock position ball;wherein said switch produces said locked signal in response to said lock position ball moving from said first position to said second position upon force of said cam surface as said lock position indicator piston is moved to said locked position from said unlocked position. 40. The locking mechanism of claim 39, wherein said switch produces said unlocked signal in response to said lock position ball moving from said second position to said first position as said cam surface moves as said lock position indicator piston is moved from said locked position to said unlocked position. 41. The locking mechanism of claim 39, further comprising a bias spring in said switch tending to force said lock position ball away from said switch.