Lift cylinder assembly

Claim 2

A lift cylinder assembly comprising a cylinder having an open end and a closed end, a piston telescopically received in said cylinder, said piston containing an axial passage, an annular groove formed in the outer surface of said piston, a first annular groove formed in said cylinder adjacent its open end, a scraper member mounted in said first groove, said scraper member being continually biased into engagement with the outer surface of said piston, a second annular groove formed in the inner surface of said cylinder inwardly of said first groove, a seal assembly secured in said second groove, a third annular groove formed in the inner surface of said cylinder inwardly of said second groove, all three of said grooves being serially positioned toward the open end of said cylinder, a split spring steel locking ring radially slidable in both said third annular groove and said piston groove when said piston is sufficiently extended aligning said grooves thereby locking said piston in a predetermined extended position, and a cam surface in one side only of one of said aligned grooves independently moving said ring radially outwardly into said third groove out of its locking position during retracting movement of said piston while simultaneously said scraper assembly removes foreign particles from the exterior surface of said piston prior to its entrance within the cylinder and said seal prevents discharge of pressure fluid through the open end of said cylinder.

Claim 3

A lift cylinder assembly comprising a sleeve-type cylinder having a closed end and an open end, a sleeve-type piston having a closed end and an open end, the open end of said piston being telescopically received within the cylinder open end for extension and retraction therein, a first annular groove formed in the inner surface of said cylinder adjacent its open end, an elastomeric wiper member disposed within said first annular groove and positioned to resiliently engage the outer surface of said piston, a frustoconical cap member secured to the outer surface of said cylinder and including an annular scraper edge at the smaller portion of the frustum of the cone lightly biased into engagement with the outer surface of the piston, Said scraper edge removing foreign particles from the piston outer surface during retracting movement thereof, a second annular groove formed in the inner surface of said cylinder inwardly of said first annular groove but toward said cylinder open end, a seal assembly secured in said second annular groove fluid tightly sealing the mating inner cylinder surface and the outer piston surface, a third annular groove formed in the inner surface of said cylinder in serial arrangement with said first and second grooves, a spring steel split locking ring disposed for radial movement in said third annular groove, an annular groove formed in the outer surface of said piston, a cam surface extending from said annular groove in said piston toward the closed end of said piston and presenting a 15* angle with the outer piston surface thereof, said piston closed end containing an axially extending stepped bore, a fluid supply conduit threadably connected in said stepped bore, a bushing ball valve seat member secured in said bore, a ball valve member, a spring biasing said ball valve member against one end surface of said bushing valve seat member, said one end surface of said valve seat member containing a plurality of radially extending grooves therein, said supply conduit conducting pressure fluid to unseat said ball member and supply fluid through said piston to said cylinder closed end whereby sufficient accumulation of fluid extends said piston until said locking ring engages the annular groove in said piston and retraction of said piston moving said cam surface against said locking ring moving it out of locking engagement with said piston allowing said piston to continue in a retracting direction while the fluid in said cylinder is forced upwardly through said piston and through the coined grooves in said valve seat member regulating the retraction of said piston.

Claim 4

A lift cylinder assembly comprising a sleeve-type cylinder having a closed end and an open end, a sleeve-type piston having a closed end and an open end, the open end of said piston being telescopically received within the cylinder open end for extension and retraction therein, a first annular groove formed in the inner surface of said cylinder adjacent its open end, an elastomeric wiper member disposed within said first annular groove and positioned to resiliently engage the outer surface of said piston, a frustoconical cap member secured to the outer surface of said cylinder and including an annular scraper edge at the smaller portion of the frustum of the cone lightly biased into engagement with the outer surface of the piston, Said scraper edge removing foreign particles from the piston outer surface during retracting movement thereof, a second annular groove formed in the inner surface of said cylinder inwardly of said first annular groove but toward said cylinder open end, a seal assembly secured in said second annular groove fluid tightly sealing the mating inner cylinder surface and the outer piston surface, a third annular groove formed in the inner surface of said cylinder in serial arrangement with said first and second grooves, a spring steel split locking ring disposed for radial movement in said third annular groove, an annular groove formed in the outer surface of said piston, a cam surface extending from said annular groove in said piston toward the closed end of said piston and presenting a 15* angle with the outer piston surface thereof, said piston closed end containing an axially extending stepped bore, a fluid supply conduit threadably connected in said stepped bore, a bushing ball valve seat member secured in said bore, a ball valve member, a spring biasing said ball valve member against one end surface of said bushing valve seat member, said one end surface of said valve seat member containing a plurality of radially extending grooves therein, said supply conduit conducting pressure fluid to unseat said ball member and supply fluid through said piston to said cylinder closed end whereby sufficient accumulation of fluid extends said piston until said locking ring engages the annular groove in said piston and retraction of said piston moving said cam surface against said locking ring moving it out of locking engagement with said piston allowing said piston to continue in a retracting direction while the fluid in said cylinder is forced upwardly through said piston and through the coined grooves in said valve seat member regulating the retraction of said piston.

Claim 5

A lift cylinder assembly comprising a sleeve-type cylinder having a closed end and an open end, a sleeve-type piston having a closed end and an open end, said piston being telescopically received within said cylinder open end and movable toward and away from said cylinder closed end, a first groove machined in the inner surface of said cylinder adjacent its open end, a plastic scraper assembly retained in said first annular groove in constant engagement with the outer surface of said piston, a second annular groove formed in the inner surface of said cylinder, a seal assembly secured in said second annular groove preventing the discharge of pressure fluid through the open end of said cylinder, a third annular conically shaped groove formed in the inner surface of said cylinder at a predetermined location therein, an annular groove formed on the outer surface of said piston at a predetermined location thereon, a frustoconical split spring steel locking ring disposed in said annular piston groove compressed therein to continuously exert an outward force against the inner surface of said cylinder, a fluid passage in said piston closed end, a valve seat member located in said passage, and a ball valve spring biased into continual engagement with one end of said valve seat member, said one end of said valve seat member including a plurality of radially extending coined grooves, pressure fluid flowing into said fluid passage unseating said ball valve and passing into said cylinder adjacent the closed cylinder end for accumulation sufficient to extend said piston until said locking ring engages said third annular groove retaining the piston in its furthermost extended position, said conically shaped locking ring and said conical annular groove comprising mating cam surfaces which upon the application of a sufficient retracting force moves the locking ring into the piston annular groove and said piston is retracted at a rate controlled by fluid flow through the coined grooves in said one end of said valve seat member.

Claim 6

A lift cylinder assembly comprising a sleeve-type cylinder having a closed end and an open end, a sleeve-type piston having a closed end and an open end, said piston being telescopically received within said cylinder open end and movable toward and away from said cylinder closed end, a first groove machined in the inner surface of said cylinder adjacent its open end, a plastic scraper assembly retained in said first annular groove in constant engagement with the outer surface of said piston, a second annular groove formed in the inner surface of said cylinder, a seal assembly secured in said second annular groove preventing the discharge of pressure fluid through the open end of said cylinder, a third annular conically shaped groove formed in the inner surface of said cylinder at a predetermined location therein, an annular groove formed on the outer surface of said piston at a predetermined location thereon, a frustoconical split spring steel locking ring disposed in said annular piston groove compressed therein to continuously exert an outward force against the inner surface of said cylinder, a fluid passage in said piston closed end, a valve seat member located in said passage, and a ball valve spring biased into continual engagement with one end of said valve seat member, said one end of said valve seat member including a plurality of radially extending coined grooves, pressure fluid flowing into said fluid passage unseating said ball valve and passing into said cylinder adjacent the closed cylinder end for accumulation sufficient to extend said piston until said locking ring engages said third annular groove retaining the piston in its furthermost extended position, said conically shaped locking ring and said conical annular groove comprising mating cam surfaces which upon the application of a sufficient retracting force moves the locking ring into the piston annular groove and said piston is retracted at a rate controlled by fluid flow through the coined grooves in said one end of said valve seat member.

Claim 7

A lift cylinder assembly comprising a sleeve-type cylinder having a closed end and an open end, a sleeve-type piston having a closed end and an open end, the piston open end being telescopically received within the cylinder open end for extension and retraction toward and away from the cylinder closed end, the open piston end and the cylinder closed end forming a fluid chamber therebetween, the piston closed end containing an axial passage therethrough, a ball check valve positioned in said axial passage, a valve seat member secured in said passage, said ball valve being spring biased against one surface of said valve seat, said one surface of the valve seat containing a plurality of radially extending passages, a supply line connected to said piston closed end supplying pressure fluid into said axial passage, said ball valve being moved away from said valve seat by said pressure fluid flowing into said sleeve-type piston, sufficient accumulation of pressure fluid in said fluid chamber extending said piston out of said cylinder, said piston containing an annular groove in the outer surface thereof, a first annular groove formed in the inner surface of said cylinder adjacent its open end, a scraper assembly positioned in said first annular groove engaging the outer surface of said piston, a second annular groove formed in the inner surface of said cylinder inwardly of said first annular groove, a fluid seal assembly secured in said second annular groove, said seal assembly fluid tightly engaging the outer surface of said piston, a third annular groove formed in the inner surface of said cylinder inwardly of said second annular groove, a split spring steel locking ring radially slidable in said third annular groove and expanded to constantly retract against the outer surface of said piston, and a cam surface in said annular piston groove, extension of said piston to a predetermined maximum distance aligning said piston annular groove and said locking ring whereby the latter contracts into said piston groove and prevents further withdrawal of the piston, movement of said piston in a retracting direction initially resulting in said cam surface moving said locking ring outwardly within said third annular groove and simultaneously resulting in a discharge of pressure fluid from said fluid chamber through the radial passages in said valve seat surface in a reverse direction through said supply line.

Claim 8

A lift cylinder assembly comprising a sleeve-type cylinder having a closed end and an open end, a sleeve-type piston having a closed end and an open end, the piston open end being telescopically received within the cylinder open end for extension and retraction toward and away from the cylinder closed end, the open piston end and the cylinder closed end forming a fluid chamber therebetween, the piston closed end containing an axial passage therethrough, a ball check valve positioned in said axial passage, a valve seat member secured in said passage, said ball valve being spring biased against one surface of said valve seat, said one surface of the valve seat containing a plurality of radially extending passages, a supply line connected to said piston closed end supplying pressure fluid into said axial passage, said ball valve being moved away from said valve seat by said pressure fluid flowing into said sleeve-type piston, sufficient accumulation of pressure fluid in said fluid chamber extending said piston out of said cylinder, said piston containing an annular groove in the outer surface thereof, a first annular groove formed in the inner surface of said cylinder adjacent its open end, a scraper assembly positioned in said first annular groove engaging the outer surface of said piston, a second annular groove formed in the inner surface of said cylinder inwardly of said first annular groove, a fluid seal assembly secured in said second annular groove, said seal assembly fluid tightly engaging the outer surface of said piston, a third annular groove formed in the inner surface of said cylinder inwardly of said second annular groove, a split spring steel locking ring radially slidable in said third annular groove and expanded to constantly retract against the outer surface of said piston, and a cam surface in said annular piston groove, extension of said piston to a predetermined maximum distance aligning said piston annular groove and said locking ring whereby the latter contracts into said piston groove and prevents further withdrawal of the piston, movement of said piston in a retracting direction initially resulting in said cam surface moving said locking ring outwardly within said third annular groove and simultaneously resulting in a discharge of pressure fluid from said fluid chamber through the radial passages in said valve seat surface in a reverse direction through said supply line.