A hydraulic jack includes a frame and a pump connected to the frame. The pump is connected to the frame. The pump includes a rod, a housing, and a piston, with hydraulic fluid being in the housing. The rod has a cross-sectional area and has a longitudinal axis. The housing has an end through which the rod slides. The housing has an interior open cross-sectional area in a direction normal to the longitudinal axis, and the housing has an interior wall. The piston is coupled to the rod. The piston establishes a rod side chamber and a piston side chamber within the housing. The piston has a cross-sectional area, which is smaller than the cross-sectional area of the housing thereby allowing a portion of the hydraulic fluid to flow between said piston and said interior wall to and from the rod side chamber and the piston side chamber when the piston is moved in the housing.

A hydraulic jack includes a frame and a pump connected to the frame. The pump is connected to the frame. The pump includes a rod, a housing, and a piston, with hydraulic fluid being in the housing. The rod has a cross-sectional area and has a longitudinal axis. The housing has an end through which the rod slides. The housing has an interior open cross-sectional area in a direction normal to the longitudinal axis, and the housing has an interior wall. The piston is coupled to the rod. The piston establishes a rod side chamber and a piston side chamber within the housing. The piston has a cross-sectional area, which is smaller than the cross-sectional area of the housing thereby allowing a portion of the hydraulic fluid to flow between said piston and said interior wall to and from the rod side chamber and the piston side chamber when the piston is moved in the housing.

A method of extending a jack including the steps of: first stage pumping by passing pressurized fluid at a first pressure and a first volume to a jack cylinder primarily by movement of a piston; and second stage pumping by passing pressurized fluid at a second pressure and a second volume to the jack cylinder primarily by movement of a rod connected to the piston.

A method of extending a jack including the steps of: first stage pumping by passing pressurized fluid at a first pressure and a first volume to a jack cylinder primarily by movement of a piston; and second stage pumping by passing pressurized fluid at a second pressure and a second volume to the jack cylinder primarily by movement of a rod connected to the piston.

A bottle jack may be manufactured differently or converted (retro-fitted) by replacing a conventional shaft in a main lift piston to be inserted and removed, at will, without tools. The threads in the main lift piston may remain or be removed. A yoke or other head is fitted to provide registration, horizontal restraint, or both against a lifted object, component, or surface to prevent sliding off the head in use. In a smooth-walled-shaft embodiment, a set of risers (spacers, adjusters, trims, or shims) provide an extension height of the shaft, elevating the head with respect to the piston prior to beginning to lift the hydraulic piston.

A bottle jack may be manufactured differently or converted (retro-fitted) by replacing a conventional shaft in a main lift piston to be inserted and removed, at will, without tools. The threads in the main lift piston may remain or be removed. A yoke or other head is fitted to provide registration, horizontal restraint, or both against a lifted object, component, or surface to prevent sliding off the head in use. In a smooth-walled-shaft embodiment, a set of risers (spacers, adjusters, trims, or shims) provide an extension height of the shaft, elevating the head with respect to the piston prior to beginning to lift the hydraulic piston.

A cylinder assembly having a housing, a pump supported within the housing, a motor supported within the housing and operable to power the pump, and a power source supported by the housing and operable to supply power to the motor. A cylinder has a first end, an opposite second end, and a sidewall extending therebetween. A piston is movably supported by the cylinder, the pump being operable to supply hydraulic fluid to the cylinder to move the piston relative to the cylinder at least from a retracted position to an advanced position. A frame is coupled to the sidewall of the cylinder and supporting the pump and the motor.

A cylinder assembly having a housing, a pump supported within the housing, a motor supported within the housing and operable to power the pump, and a power source supported by the housing and operable to supply power to the motor. A cylinder has a first end, an opposite second end, and a sidewall extending therebetween. A piston is movably supported by the cylinder, the pump being operable to supply hydraulic fluid to the cylinder to move the piston relative to the cylinder at least from a retracted position to an advanced position. A frame is coupled to the sidewall of the cylinder and supporting the pump and the motor.

A hydraulic oil-circuit system and a hydraulic jack are proposed. The hydraulic oil-circuit system includes a hydraulic cylinder, an oil loading chamber, a storage oil chamber and an oil unloading pipeline; a piston is arranged in the hydraulic cylinder and divides the hydraulic cylinder into a first hydraulic oil chamber and a second hydraulic oil chamber; the first hydraulic oil chamber has a first oil port, and the second hydraulic oil chamber has a second oil port; the first oil port and the second oil port are both in unidirectional communication with the oil loading chamber and are both in unidirectional communication with the storage oil chamber; and the oil unloading pipeline connects the oil loading chamber and the storage oil chamber.

A hydraulic oil-circuit system and a hydraulic jack are proposed. The hydraulic oil-circuit system includes a hydraulic cylinder, an oil loading chamber, a storage oil chamber and an oil unloading pipeline; a piston is arranged in the hydraulic cylinder and divides the hydraulic cylinder into a first hydraulic oil chamber and a second hydraulic oil chamber; the first hydraulic oil chamber has a first oil port, and the second hydraulic oil chamber has a second oil port; the first oil port and the second oil port are both in unidirectional communication with the oil loading chamber and are both in unidirectional communication with the storage oil chamber; and the oil unloading pipeline connects the oil loading chamber and the storage oil chamber.