Methods and systems relating to improvements in reliability of fluid power actuators are disclosed. An exemplary fluid power actuator (300) comprises, an actuator body (305) having a cylindrical cavity (310), fitted with a first end cap (315) and a second end cap (320) at longitudinal ends, a piston (325) with a piston rod (330) disposed inside the cylindrical cavity (310), wherein the actuator (300) is characterised by, a hollow tie rod (335) in the cylindrical cavity (310), wherein the hollow tie rod (335) is for conveying a pressurised fluid into a volume (A) in the cylindrical cavity (310) between the second end cap (320) and the piston (325) for exerting a force on the piston (325) for a stroke or stroke reversal. The hollow tie rod 335 serves dual purpose of holding the pressure retaining components together, providing a flow path for the fluid enabling actuator stroking and stroke reversal.

A manufacturing method for manufacturing a cylinder tube includes a joining step of joining a tube main body and a head member by friction welding by abutting an end surface of the tube main body and a flange portion of the head member in a state in which a through hole of the tube main body and a projecting portion of the head member are fitted to each other so as to form a predetermined clearance. In the joining step, a non-contact portion of the flange portion of the head member facing the clearance is joined to the tube main body by heating the non-contact portion with friction heat generated by relative rotation between the tube main body and the head member.

A cylinder includes a cylinder tube, a first closure part, a second closure part, and a piston unit. The cylinder tube has a first tube end and a second tube end. The tube and end closure parts define a cylinder interior. The piston unit defines at least one working space in the cylinder interior. The first closure part is connected to the tube by a first peripheral laser ring weld and the second closure part is connected to the tube by a second peripheral laser ring weld. The laser ring welds each define a fluid-tight sealing plane. A peripheral sealing ring is located between each closure part and a tube inner wall at an axial distance from the associated laser ring weld seam. The peripheral sealing ring defines a pressure-separated ring section between the peripheral sealing ring and the associated laser ring weld seam.

A working cylinder has a cylinder tube, a first closure part, a second closure part and a piston unit. The first closure part is arranged on a first cylinder tube end, the second closure part is arranged on a second cylinder tube end to define a cylinder interior. The piston unit defines at least one working chamber in the cylinder interior. The piston unit slides through the first closure part. The first closure part is joined to the cylinder tube by a first peripheral laser ring weld seam and the second closure part is joined to the cylinder tube by a second peripheral laser ring weld seam. The laser ring weld seams each define a fluid-tight sealing plane. A method for producing the working cylinder is provided.

A working cylinder has a cylinder tube, a first closure part, a second closure part and a piston unit. The first closure part is arranged at a first cylinder tube end and the second closure part is arranged at a second cylinder tube end, the cylinder tube and the first and second closure parts define a cylinder interior. The piston unit defines at least one working chamber in the cylinder interior. The piston unit slidably passes through the first closure part. The first closure part us joined to the cylinder tube in a positive-locking manner by a first circumferential laser ring weld seam. The second closure part is joined to the cylinder tube in a positive-locking manner by a second circumferential laser ring weld seam, and each of the laser ring weld seams define a fluid-tight sealing plane. At least one of the closure parts has an axially opening that is a circumferential concave receiving contour in which the cylinder tube engages. The receiving contour radially overlaps the cylinder tube, and a ring weld seam inclination angle thereof is 110 to 160 degrees.

Disclosed is a method for repairing a piston-cylinder unit within a working machine or within an attachment, wherein a connection of the piston rod with the machine or implement structure is released and the piston rod, the piston and at least one bearing head is jointly removed from the cylinder housing as an assembly and replaced by a premounted substitute assembly consisting of piston rod, piston and at least one bearing head.

A dual-direction piston-based actuator housing assembly has a housing disposed over a hollow cylindrical liner configured to accept within a movable piston. A compression block having a pin engagement hole is disposed adjacent to a proximal end of the liner. A tension strap is disposed over the compression block, the tension strap starting from a first end near the proximal end of the liner, extending around the engagement hole and back to a second end near the proximal end of the liner. An overwind extends over the first and second ends of the tension strap, over the compression block, and over the proximal end of the housing. A tension clip is disposed at the distal end of the liner and embedded within the housing. The housing, tension strap and overwind may be a continuous fiber reinforced plastic composite and the compression block may be a chopped fiber filled thermoplastic composite.

A pump rod has a head extending from a neck, and the head is received within a drive slot of a drive link. The head includes a projection, and has an area smaller than an area of the head. The projection contacts an inner surface of the drive slot. The drive link may include a projection aligned with a centerline of the drive link. The drive link projection contacts a head of the pump rod. The projections provide a reduced contact area between the pump rod and the drive link, thereby reducing any side-loading on the pump rod and increasing a lifespan of the wear parts.

Disclosed is a method for repairing a piston-cylinder unit within a working machine or within an attachment, wherein a connection of the piston rod with the machine or implement structure is released and the piston rod, the piston and at least one bearing head is jointly removed from the cylinder housing as an assembly and replaced by a premounted substitute assembly consisting of piston rod, piston and at least one bearing head.

An actuator is provided. The actuator includes a first body defining an interior, a second body disposed about the first body and defining space between an exterior of the first body and an interior of the second body, a plunger including a head sealably disposed in the interior and a rod connected to the head and sealably extended through the first and second bodies and first and second fluid systems. The first fluid system is insulated from the space. A first fluid is moved relative to the interior for causing the plunger to extend or retract by way of the first fluid system. A second fluid is moved through the space by way of the second fluid system.