Actuator lock

Claim 2

A linear actuator comprising a cylinder, a piston axially slidably received in said cylinder, a hollow rod extending from said piston through the rod end of said cylinder, and an actuator lock for selectively limiting axial movement of said rod relative to said cylinder comprising a lock shaft, means mounting said lock shaft against axial movement relative to said cylinder, said lock shaft being rotatably journaled in the head end of said cylinder, said lock shaft extending through an opening in said piston into said hollow rod, said rod and lock shaft having multi-splined portions of corresponding shape which when properly aligned and in mating engagement with each other permit axial movement of said rod relative to said cylinder while preventing relative rotation between said rod and lock shaft and when out of alignment with each other limit such axial movement, the splined portion on one of said rod and lock shaft having at least one relieved area of a length at least equal to the length of the splined portion on the other of said rod and lock shaft, and means for rotating said lock shaft relative to said rod when the splined portion on the other of said rod and lock shaft is in axial alignment with said relieved area for selectively aligning and misaligning said splined portions.

Claim 3

The linear actuator of claim 1 wherein there are a plurality of axially spaced relieved areas interrupting the splined portion on said one of said rod and lock shaft to provide plural lock positions for said actuator permitting rotation of the splined portion on the other of said rod and lock shaft when brought into axial alignment with any one of said relieved areas.

Claim 4

The linear actuator of claim 1 wherein said relieved area and said splined portion on the other of said rod and lock shaft are of approximately the same length, whereby when said splined portion on the other of said rod and lock shaft is rotated in said relieved area to misalign said splined portions, said rod is locked against axial movement.

Claim 5

The linear actuator of claim 1 wherein said relieved area is of a length greater than the length of the splined portion on the other of said rod and lock shaft to permit limited movement of said splined portion on the other of said rod and lock shaft between the ends of said relieved area when rotated therewithin to misalign said splined portions.

Claim 6

The linear actuator of claim 1 wherein said relieved area is on said hollow rod, and said lock shaft has a land on the free end thereof having said splined portion thereon.

Claim 7

The linear actuator of claim 1 wherein said relieved area is on said lock shaft.

Claim 8

The linear actuator of claim 1 wherein there are splined portions adjacent opposite ends of said relieved area.

Claim 9

The linear actuator of claim 7 wherein said splined portions adjacent opposite ends of said relieved area are out of alignment with each other, whereby when said splined portion on the other of said rod and lock shaft is in alignment with the splined portion adjacent one end of said relieved area, it is out of alignment with the splined portion adjacent the other end of said relieved area.

Claim 10

The linear actuator of claim 8 wherein said splined portions adjacent opposite ends of said relieved areas are of the same shape but misaligned by making such splined portions unsymmetrical at different places around their circumferential extent, and said splined portion on the other of said rod and lock shaft is of a corresponding shape to permit selective alignment and misalignment of said splined portion on said other of said rod and lock shaft with said splined portions adjacent opposite ends of said relieved area by rotating said lock shaft relative to said rod.

Claim 11

The linear actuator of claim 1 further comprising a screw shaft journaled for rotation in said cylinder, said screw shaft extending into said hollow rod and having a threaded connection with said piston, said screw shaft having a central opening for extension of said lock shaft therethrough, said lock shaft having a land on which one of said splined portions is provided adjacent the free end of said screw shaft for direct transmission of column loads applied to said lock shaft to said screw shaft.

Claim 12

The linear actuator of claim 1 wherein said means for rotating said lock shaft comprises a hydraulic cylinder, and crank means on said lock shaft for converting the linear input of said hydraulic cylinder to a rotational torque input.

Claim 13

The linear actuator of claim 1 wherein said means for rotating said lock shaft comprises a linear input device, crank means on said lock shaft for converting the linear input to a rotational torque input, and spring means between said linear input device and crank means to limit the force applied to said lock shaft by said linear input device.

Claim 14

A linear actuator comprising a cylinder, a piston axially slidably received in said cylinder, a hollow rod extending from said piston through the rod end of said cylinder, and an actuator lock for selectively limiting axial movement of said rod relative to said cylinder comprising two lock shafts rotatably journaled in the head end of said cylinder, said lock shafts extending through an opening in said piston into said hollow rod, said rod having splined portions of different diameters, and said lock shafts having different diameter splined portions for selective alignment and misalignment with the splined portions on said rod, said splined portions on said rod and lock shafts when in mating engagement with each other permitting axial movement of said rod relative to said cylinder and when out of alignment with each other limiting such axial movement, the splined portions on one of said rod and lock shafts having at least one relieved area of a length at least equal to the length of the splined portions on the other of said rod and lock shafts to permit rotation of said lock shafts relative to said rod when the splined portions on the other of said rod and lock shafts are in axial alignment with said relieved area for selectively aligning and misaligning said splined portions, and means for rotating said lock shafts.

Claim 15

A linear actuator comprising a cylinder, a piston axially slidably received in said cylinder, a hollow rod extending from said piston through the rod end of said cylinder, and an actuator lock for selectively limiting axial movement of said rod relative to said cylinder comprising two lock shafts rotatably journaled in the head end of said cylinder, said lock shafts extending through an opening in said piston into said hollow rod, said rod having splined portions of different diameters, and said lock shafts having different diameter splined portions for selective alignment and misalignment with the splined portions on said rod, said splined portions on said rod and lock shafts when in mating engagement with each other permitting axial movement of said rod relative to said cylinder and when out of alignment with each other limiting such axial movement, the splined portions on one of said rod and lock shafts having at least one relieved area of a length at least equal to the length of the splined portions on the other of said rod and lock shafts to permit rotation of said lock shafts relative to said rod when the splined portions on the other of said rod and lock shafts are in axial alignment with said relieved area for selectively aligning and misaligning said splined portions, and means for rotating said lock shafts.