A hydraulic system can include a hydraulic actuator including a piston rod slidably disposed within a housing having a base-side port and a rod-side port, a hydraulic pump, a hydraulic reservoir, an accumulator, a first control valve operable to selectively control flow from the pump to the base-side port and from the base-side port to the reservoir, a second control valve operable to selectively control flow from the pump to the rod-side port and from the rod-side port to the reservoir, a third control valve operable to selectively allow flow between the base-side port and the accumulator, and a controller for operating the hydraulic system and including a ride control mode in which damping is provided to the hydraulic actuator by operation of the first, second, and third control valves.

A device for the deaeration of a hydraulic fluid of a hydraulic system has at least one hydraulic motor arrangement and a hydraulic fluid storage which is hydraulically coupled with this hydraulic motor arrangement. A suction device for sucking out the hydraulic fluid is associated with the at least one hydraulic motor arrangement such that the suction device guides hydraulic fluid out of the hydraulic motor arrangement into the hydraulic fluid storage by means of vacuum pressure (Δp). The suction device is constructed as a jet pump and is integrated in the return line between the hydraulic motor arrangement and hydraulic fluid storage.

A device for the deaeration of a hydraulic fluid of a hydraulic system has at least one hydraulic motor arrangement and a hydraulic fluid storage which is hydraulically coupled with this hydraulic motor arrangement. A suction device for sucking out the hydraulic fluid is associated with the at least one hydraulic motor arrangement such that the suction device guides hydraulic fluid out of the hydraulic motor arrangement into the hydraulic fluid storage by means of vacuum pressure (Δp). The suction device is constructed as a jet pump and is integrated in the return line between the hydraulic motor arrangement and hydraulic fluid storage.

Mainframes for a self-propelled machine are disclosed. The mainframe includes first and second pockets that extend from the front end to the rear end of the mainframe. A hydraulic reservoir housing extends from the first side to the second side of the mainframe. The hydraulic reservoir housing is disposed between the front end of the mainframe and first and second drive openings.

Mainframes for a self-propelled machine are disclosed. The mainframe includes first and second pockets that extend from the front end to the rear end of the mainframe. A hydraulic reservoir housing extends from the first side to the second side of the mainframe. The hydraulic reservoir housing is disposed between the front end of the mainframe and first and second drive openings.

When a fluid control valve is opened and closed, the port pressure of fluid control valve is guided to a main relief valve through a first passage, and its maximum pressure is controlled by the main relief valve. At the same time, the port pressure of fluid control valve is guided to pressure compensation valves of the respective fluid control valves. As a result, even when functions having different load pressures are simultaneously operated in the fluid control valves, constant operability can be always secured without depending on the load pressures. In addition, when the fluid control valve, which drives a tilt cylinder for a function of tilting a fork, is opened and closed, the port pressure of the fluid control valve is guided to a secondary relief valve through a second passage, and is also guided to the main relief valve and the pressure compensation valves of the respective fluid control valves through the first passage.

When a fluid control valve is opened and closed, the port pressure of fluid control valve is guided to a main relief valve through a first passage, and its maximum pressure is controlled by the main relief valve. At the same time, the port pressure of fluid control valve is guided to pressure compensation valves of the respective fluid control valves. As a result, even when functions having different load pressures are simultaneously operated in the fluid control valves, constant operability can be always secured without depending on the load pressures. In addition, when the fluid control valve, which drives a tilt cylinder for a function of tilting a fork, is opened and closed, the port pressure of the fluid control valve is guided to a secondary relief valve through a second passage, and is also guided to the main relief valve and the pressure compensation valves of the respective fluid control valves through the first passage.

A forklift truck includes a carriage that moves up and down by a mast assembly in a multi-stage structure including an outer mast, a first inner mast accommodated in the outer mast, and a second inner mast accommodated in the first inner mast. The forklift truck includes a first lift cylinder configured to move the first inner mast up and down; a second lift cylinder configured to move the second inner mast up and down and having a pressure reception area less than a pressure reception area of the first lift cylinder. A first lift hydraulic line supplies hydraulic oil to the first lift cylinder. A second lift hydraulic line supplies hydraulic oil to the second lift cylinder. A pressure regulating valve is provided to increase a pressure of the hydraulic oil to a pressure capable of driving the second lift cylinder.

A forklift truck includes a carriage that moves up and down by a mast assembly in a multi-stage structure including an outer mast, a first inner mast accommodated in the outer mast, and a second inner mast accommodated in the first inner mast. The forklift truck includes a first lift cylinder configured to move the first inner mast up and down; a second lift cylinder configured to move the second inner mast up and down and having a pressure reception area less than a pressure reception area of the first lift cylinder. A first lift hydraulic line supplies hydraulic oil to the first lift cylinder. A second lift hydraulic line supplies hydraulic oil to the second lift cylinder. A pressure regulating valve is provided to increase a pressure of the hydraulic oil to a pressure capable of driving the second lift cylinder.

A computer-implemented method is provided for controlling a work tool coupled to a frame of a work vehicle and moveable relative thereto, wherein the work tool is configured in a first mode to apply an enclosing pressure on a load and in a second mode to release the enclosing pressure on the load. At least one work state of the work vehicle is determined. In association with the first mode, which may for example be user-selectable or otherwise determined in view of the work state, a configuration setting corresponding to the at least one work state of the work vehicle is automatically selected from data storage, and a control signal is generated for controlling an actuator associated with an amount of enclosing pressure applied by the work tool and upon the load, based at least in part on the selected configuration setting.