In order to secure a reached extension position of a piston rod (22, 22) of an in particular multi stage operating cylinder device (100) with at least one operating cylinder unit (50) not only through the operating pressure in the cylinder (1, 1) of the operating cylinder unit (50) but additionally mechanically, a mechanical safety through interlocking safety elements (4a, b) in the interior of the operating cylinder device (100) is provided which is activated exclusively by the operating pressure in the first pressure cavity and disengaged by a pressure in a second operating cavity.

In order to secure a reached extension position of a piston rod (22, 22) of an in particular multi stage operating cylinder device (100) with at least one operating cylinder unit (50) not only through the operating pressure in the cylinder (1, 1) of the operating cylinder unit (50) but additionally mechanically, a mechanical safety through interlocking safety elements (4a, b) in the interior of the operating cylinder device (100) is provided which is activated exclusively by the operating pressure in the first pressure cavity and disengaged by a pressure in a second operating cavity.

A central column allowing a 360 rotation on its central axis comprises mechanical safety locks and load sensors for safe operation in vertical and horizontal movements. The central rotating column may be part of a mounting and dismounting system for mining truck dump bodies and water truck bodies, providing two adjacent working areas. The lifting system for dump bodies of mining trucks and bodies of water trucks comprises a vertically adjustable mechanical lock; a spring-actuated automatic lock horizontally holding the column in position; an automatic rotation lock preventing the column from rotating while in operation; a toothed crown and pinion assembly integrated to the rotating base and allowing a 360 movement, and a load sensor preventing the horizontal movement of the column under load.

A central column allowing a 360 rotation on its central axis comprises mechanical safety locks and load sensors for safe operation in vertical and horizontal movements. The central rotating column may be part of a mounting and dismounting system for mining truck dump bodies and water truck bodies, providing two adjacent working areas. The lifting system for dump bodies of mining trucks and bodies of water trucks comprises a vertically adjustable mechanical lock; a spring-actuated automatic lock horizontally holding the column in position; an automatic rotation lock preventing the column from rotating while in operation; a toothed crown and pinion assembly integrated to the rotating base and allowing a 360 movement, and a load sensor preventing the horizontal movement of the column under load.

A lifting device including a first platform, a second platform, a gas spring and a locking device is provided. The first platform includes a base and a first column connected to each other. The second platform includes a working table and a second column connected to each other. The second column and the first column are movably connected. The second column has a plurality of engaging holes. The gas spring includes a first end and a second end opposite to each other. The first end connected to the first column, and the second end connected to the second column. The locking device partially disposed at the first column, and a portion of the locking device being adapted to penetrate the engaging holes to fix a relative position between the second column and the first column.

A lifting device including a first platform, a second platform, a gas spring and a locking device is provided. The first platform includes a base and a first column connected to each other. The second platform includes a working table and a second column connected to each other. The second column and the first column are movably connected. The second column has a plurality of engaging holes. The gas spring includes a first end and a second end opposite to each other. The first end connected to the first column, and the second end connected to the second column. The locking device partially disposed at the first column, and a portion of the locking device being adapted to penetrate the engaging holes to fix a relative position between the second column and the first column.

A jack for lifting segments of a structure includes a pair of masts, a mast base, a mast cap, a hydraulic ram, a bottom bracket and a shuttle. The masts are identical and upright with a plurality of evenly spaced holes. The mast base supports the mast and the mast cap receives the upper ends of the masts and maintains the masts in a parallel, relationship. The hydraulic ram moves between a retracted position and an extended position with a stroke distance which is significantly less than the mast height. The bottom bracket is removably pinned to the masts and receives and supports the lower end of the hydraulic ram. The shuttle receives the upper end of the hydraulic ram. The bottom bracket and shuttle, when not pinned to the masts, can slide vertically up the masts. The shuttle includes features for connecting to a segment of a structure.

A jack for lifting segments of a structure includes a pair of masts, a mast base, a mast cap, a hydraulic ram, a bottom bracket and a shuttle. The masts are identical and upright with a plurality of evenly spaced holes. The mast base supports the mast and the mast cap receives the upper ends of the masts and maintains the masts in a parallel, relationship. The hydraulic ram moves between a retracted position and an extended position with a stroke distance which is significantly less than the mast height. The bottom bracket is removably pinned to the masts and receives and supports the lower end of the hydraulic ram. The shuttle receives the upper end of the hydraulic ram. The bottom bracket and shuttle, when not pinned to the masts, can slide vertically up the masts. The shuttle includes features for connecting to a segment of a structure.

A lift system includes a cylinder having an end surface, a threaded member supported for movement with a piston, and a nut threadedly engaging the threaded member and selectively engageable with the end surface. Engagement of the nut and the end surface limits axial movement of the piston relative to the cylinder in at least one direction. A drive mechanism rotates the nut relative to the threaded member, and a control valve controls movement of the piston relative to the cylinder. A drive control mechanism controls operation of the drive mechanism and rotation of the nut. A nut sensor senses a portion of the nut. The nut sensor is in communication with at least one of the control valve and the drive control mechanism. When the nut sensor detects a portion of the nut, the control valve stops movement of the piston or the drive control mechanism stops rotation of the nut.

A lift system includes a cylinder having an end surface, a threaded member supported for movement with a piston, and a nut threadedly engaging the threaded member and selectively engageable with the end surface. Engagement of the nut and the end surface limits axial movement of the piston relative to the cylinder in at least one direction. A drive mechanism rotates the nut relative to the threaded member, and a control valve controls movement of the piston relative to the cylinder. A drive control mechanism controls operation of the drive mechanism and rotation of the nut. A nut sensor senses a portion of the nut. The nut sensor is in communication with at least one of the control valve and the drive control mechanism. When the nut sensor detects a portion of the nut, the control valve stops movement of the piston or the drive control mechanism stops rotation of the nut.