Piston lock for power cylinders

Claim 2

The combination with a cylinder and a piston reciprocable in said cylinder of a locking mechanism adjacent one end of said cylinder selectively engageable with and releasable from said piston when the latter is at the end of its travel at the mentioned end of the cylinder, the locking mechanism including means operative by engagement of said locking mechanism with said piston to hold the later at the end of its travel and simultaneously to apply a constant pressure thereagainst axially in the direction of said travel and toward said mentioned end of the cylinder.

Claim 3

The combination as set forth in claim 1 wherein said piston is provided with a part having a shoulder; and wherein said locking mechanism comprises a powered actuator movable into and out of position behind said shoulder, at least one of said shoulder and said actuator having a beveled surface and said actuator being operative through said beveled surface to lock said piston in the held position and to exert said axial pressure against said piston.

Claim 4

The combination as set forth in claim 2 wherein the mentioned part of said piston is in the form of headed pin means carried by and projecting axially from said piston; and wherein said powered actuator interfits with said headed pin means to lock and exert axial pressure against said piston.

Claim 5

The combination as set forth in claim 2 wherein the mentioned part of said piston comprises a plurality of headed pins on and projecting axially from said piston; and wherein said cylinder is provided in the mentioned end thereof with sockets disposed to receive said headed pins and operative to position the latter for engagement by said powered actuator.

Claim 6

The combination as set forth in claim 4 wherein said powered actuator comprises a rotatably movable ring mounted in the mentioned end of the cylinder and a fluid motor including a plunger operatively connected to said ring to oscillate the same, said ring having a plurality of keyhole slots disposed to receive said headed pins in one oscillatory position of said ring and to engage behind the headed portions of said pins in another oscillatory position of said ring, at least one of said pins and said keyhole slots having beveled surfaces operable by oscillating movement of said ring to exert axial pressure on said piston through said pins.

Claim 7

The combination as set forth in claim 5 wherein the operative connection between said plunger and said ring comprises a pivot on and movable with said ring, and a bearing block journaled on said pivot and carried by and slidable transversely relative to said plunger; and wherein one of said headed pins and the socket associated therewith is relatively longer than the other of said pins and operative to position said ring and said piston selectively rotatably in said cylinder properly with respect to said plunger.

Claim 8

The combinaTion with a cylinder and a piston reciprocable in said cylinder between predetermined limit positions by a fluid medium under pressure, of a locking mechanism for holding said piston under mechanical pressure in at least one of said limit positions against a load upon release of pressure on said fluid medium, said locking mechanism comprising a locking element operably associated with said piston and movable therewith, and a locking member independent of said piston and said locking element movable between nonlocking and locking positions, said locking member in nonlocking position being disengaged and released from said piston and said locking element so as to permit the piston to reciprocate in said cylinder and said locking member in locking position being in locking engagement with said locking element to hold said piston under mechanical pressure, said locking element and said locking member being movable relative to each other without interference during movement of said piston to said one limit position, and means operably associated with sad locking member for moving the latter into said locking relationship and engagement with said locking element when the latter and said piston are in said one limit position, whereby said locking member exerts a resistance to reciprocating movement of said piston from said one limit position at least equal to the load on said piston upon release of pressure on said fluid medium, said means being operable to release said locking member from said locking element to permit a return reciprocatory travel of said position.

Claim 9

The combinaTion with a cylinder and a piston reciprocable in said cylinder between predetermined limit positions by a fluid medium under pressure, of a locking mechanism for holding said piston under mechanical pressure in at least one of said limit positions against a load upon release of pressure on said fluid medium, said locking mechanism comprising a locking element operably associated with said piston and movable therewith, and a locking member independent of said piston and said locking element movable between nonlocking and locking positions, said locking member in nonlocking position being disengaged and released from said piston and said locking element so as to permit the piston to reciprocate in said cylinder and said locking member in locking position being in locking engagement with said locking element to hold said piston under mechanical pressure, said locking element and said locking member being movable relative to each other without interference during movement of said piston to said one limit position, and means operably associated with sad locking member for moving the latter into said locking relationship and engagement with said locking element when the latter and said piston are in said one limit position, whereby said locking member exerts a resistance to reciprocating movement of said piston from said one limit position at least equal to the load on said piston upon release of pressure on said fluid medium, said means being operable to release said locking member from said locking element to permit a return reciprocatory travel of said position.

Claim 10

The combination with a cylinder and a piston reciprocable in said cylinder of a locking mechanism for said piston comprising locking means on said piston, and retaining means independent of said piston movable into wedging locking engagement with said locking means, said locking means and said retaining means being axially movable relative to each other without interference during reciprocation of said piston to and from a predetermined limit position in said cylinder in which said locking means and said retaining means are movable relative to each other into a wedging relationship, and actuator means operably associated with said retaining means for moving the latter into said wedging relationship, whereby said retaining means exerts a force on said locking means which creates a resistance to return reciprocatory movement of the piston at least equal to any load on the piston, said actuator means being operable to release said retaining means from said locking means to permit return travel of the piston.

Claim 11

The combination with a cylinder and a piston reciprocable in said cylinder of a locking mechanism for said piston comprising locking means on said piston, and retaining means independent of said piston movable into wedging locking engagement with said locking means, said locking means and said retaining means being axially movable relative to each other without interference during reciprocation of said piston to and from a predetermined limit position in said cylinder in which said locking means and said retaining means are movable relative to each other into a wedging relationship, and actuator means operably associated with said retaining means for moving the latter into said wedging relationship, whereby said retaining means exerts a force on said locking means which creates a resistance to return reciprocatory movement of the piston at least equal to any load on the piston, said actuator means being operable to release said retaining means from said locking means to permit return travel of the piston.

Claim 12

The combination with a cylinder and a piston reciprocable in said cylinder between predetermined limit positions by a fluid medium under pressure of a locking mechanism for holding said piston in at least one of said limit positions against a load upon release of pressure on said fluid medium, said locking mechanism comprising a locking element carried by said piston, and a powered actuator swingable relative to said locking element into a wedging locking position with said locking element, at least one of said locking element and said actuator having a beveled surface, said locking element and said actuator being movable relative to each other without interference during reciprocatory movement of said piston to said limit position, said actuator being movable into said wedging relationship with said locking element and operable through said beveled surface to lock said piston in the limit position, said actuator adapted to exert an axial force on said locking element which resists return movement of said piston from said limit position, said force being at least equal to any load that may occur on the piston upon release of pressure on said fluid medium, said actuator being releasable from said locking element to permit said return movement of said piston.

Claim 13

The combination with a cylinder and a piston reciprocable in said cylinder between predetermined limit positions by a fluid medium under pressure of a locking mechanism for holding said piston in at least one of said limit positions against a load upon release of pressure on said fluid medium, said locking mechanism comprising a locking element carried by said piston, and a powered actuator swingable relative to said locking element into a wedging locking position with said locking element, at least one of said locking element and said actuator having a beveled surface, said locking element and said actuator being movable relative to each other without interference during reciprocatory movement of said piston to said limit position, said actuator being movable into said wedging relationship with said locking element and operable through said beveled surface to lock said piston in the limit position, said actuator adapted to exert an axial force on said locking element which resists return movement of said piston from said limit position, said force being at least equal to any load that may occur on the piston upon release of pressure on said fluid medium, said actuator being releasable from said locking element to permit said return movement of said piston.

Claim 14

The combination with a cylinder and a piston reciprocable in said cylinder of a lockIng mechanism comprising a locking element on said piston and a camming element independent of said piston, said camming element having a cam surface selectively engageable with and releasable from said piston-locking element at one end position of said piston travel in said cylinder in which at least a portion of said piston-locking element is in a position forward of the cam surface of said camming element, said camming element being operative by a camming action on said piston-locking element to hold the piston at the end of its travel and being adapted to exert a force on said camming element sufficient to resist any external load on said piston and at least equal to the forces applied by the piston against such load.

Claim 15

The combination with a cylinder and a piston reciprocable in said cylinder of a lockIng mechanism comprising a locking element on said piston and a camming element independent of said piston, said camming element having a cam surface selectively engageable with and releasable from said piston-locking element at one end position of said piston travel in said cylinder in which at least a portion of said piston-locking element is in a position forward of the cam surface of said camming element, said camming element being operative by a camming action on said piston-locking element to hold the piston at the end of its travel and being adapted to exert a force on said camming element sufficient to resist any external load on said piston and at least equal to the forces applied by the piston against such load.

Claim 16

The combination with a cylinder and a piston reciprocable in said cylinder of a locking mechanism adjacent one end of the cylinder selectively engageable with and releasable from said piston when the latter is at the end of its travel at said one end of the cylinder, said piston being provided with a part having a shoulder, said locking mechanism comprising a powered actuator movable into and out of a position behind said shoulder, at least one of said shoulder and said actuator having a beveled surface against which said actuator wedges when positioned behind said shoulder, said actuator being operative through said beveled surface to hold and lock said piston at the mentioned end of said cylinder and by pressure against said beveled surface being operative to exert an axial force urging said piston in the direction of its travel toward said one end of said cylinder.

Claim 17

The combination with a cylinder and a piston reciprocable in said cylinder of a locking mechanism adjacent one end of the cylinder selectively engageable with and releasable from said piston when the latter is at the end of its travel at said one end of the cylinder, said piston being provided with a part having a shoulder, said locking mechanism comprising a powered actuator movable into and out of a position behind said shoulder, at least one of said shoulder and said actuator having a beveled surface against which said actuator wedges when positioned behind said shoulder, said actuator being operative through said beveled surface to hold and lock said piston at the mentioned end of said cylinder and by pressure against said beveled surface being operative to exert an axial force urging said piston in the direction of its travel toward said one end of said cylinder.