Abstract: An industrial truck (2) with a lift mast (4), a hydraulic system (10), and a method for operating a hydraulic system (10). The lift mast (4) of the industrial truck (2) is driven by a mast lift cylinder (12) and includes at least one mast lift stage (42). A free lift stage is present that is driven by a free lift cylinder (8) with which a load receiving means (6) can be displaced along the lift mast (4). The industrial truck (2) includes a hydraulic system (10) for supplying the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) with a hydraulic fluid (14). The hydraulic system (10) is configured to at least at times simultaneously actuate the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) in load lifting operation and/or in load lowering operation.

Abstract: An industrial truck (2) with a lift mast (4), a hydraulic system (10), and a method for operating a hydraulic system (10). The lift mast (4) of the industrial truck (2) is driven by a mast lift cylinder (12) and includes at least one mast lift stage (42). A free lift stage is present that is driven by a free lift cylinder (8) with which a load receiving means (6) can be displaced along the lift mast (4). The industrial truck (2) includes a hydraulic system (10) for supplying the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) with a hydraulic fluid (14). The hydraulic system (10) is configured to at least at times simultaneously actuate the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) in load lifting operation and/or in load lowering operation.

Abstract: The invention relates to an industrial truck (2) with a lift mast (4), a hydraulic system (10) as well as a method for operating a hydraulic system (10). The lift mast (4) of the industrial truck (2) is driven by a mast lift cylinder (12) and comprises at least one mast lift stage (42, 42). Furthermore, a free lift stage is present that is driven by a free lift cylinder (8) with which a load receiving means (6) can be displaced along the lift mast (4). The industrial truck (2) comprises a hydraulic system (10) for supplying the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) with a hydraulic fluid (14), wherein the hydraulic system (10) is configured to at least at times simultaneously actuate the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) in load lifting operation and/or in load lowering operation.

Abstract: A lifting device for an industrial truck comprises a lift frame with a moveably guided load carrier and at least one moveably guided mast stage. A free lift cylinder is configured to actuate the load carrier and at least one mast lift cylinder is configured to actuate the at least one mast stage. A hydraulic assembly supplies the free lift cylinder and the at least one mast lift cylinder with hydraulic fluid and further comprises at least one delivery valve and at least one recirculating valve.

Abstract: The invention relates to an industrial truck (2) with a lift mast (4), a hydraulic system (10) as well as a method for operating a hydraulic system (10). The lift mast (4) of the industrial truck (2) is driven by a mast lift cylinder (12) and comprises at least one mast lift stage (42, 42). Furthermore, a free lift stage is present that is driven by a free lift cylinder (8) with which a load receiving means (6) can be displaced along the lift mast (4). The industrial truck (2) comprises a hydraulic system (10) for supplying the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) with a hydraulic fluid (14), wherein the hydraulic system (10) is configured to at least at times simultaneously actuate the at least one mast lift cylinder (12) and the at least one free lift cylinder (8) in load lifting operation and/or in load lowering operation.

Abstract: A lifting device for an industrial truck comprises a lift frame with a moveably guided load carrier and at least one moveably guided mast stage. A free lift cylinder is configured to actuate the load carrier and at least one mast lift cylinder is configured to actuate the at least one mast stage. A hydraulic assembly supplies the free lift cylinder and the at least one mast lift cylinder with hydraulic fluid and further comprises at least one delivery valve and at least one recirculating valve.

Abstract: Device for the emergency lowering of a load carrying means for a stacker truck, in particular a reach-type forklift truck, with a valve arrangement accommodated in a valve block, via which the inflow and outflow of a hydraulic means is regulated to and from a lift cylinder for the load carrying means, with a bypass between the lift cylinder and a tank, with a barrier element in the bypass. The barrier element is screwed into a threaded bore of the valve block and, in the fully screwed-in position, closes off the bypass branch. One end of a cable transmitting a torque is rotationally fixedly connected to the barrier element and the other end of the cable has a handle for turning the cable.

Abstract: Method for the adjustment of a control current of current-controlled, hysteresis-affected hydraulic valves for the actuation of individual hydraulic functions of industrial trucks, the control current being generated in an electronic control device according to a manually pre-set transmitter signal, characterised by the following steps for each hydraulic function which is controlled by a hydraulic valve, an average characteristic line I=f(Q) is determined by experiments or via calculation, in which I is the control current and Q is the volume flux of the hydraulic medium flowing through the hydraulic valve, the specific characteristic line I.sub.

Abstract: A floor conveyor with a drive portion and a load portion, wherein the load portion has a lifting scaffold, on which a carrier for a load fork or an attachment device is guided to be adjustable in height, and at least one hydraulic adjusting cylinder is assigned to the carrier for adjusting the load fork or a part on the attachment device, and wherein a hydraulic pump driven by a motor is arranged in the drive portion, which is connected to the adjusting cylinder via a proportional valve and hydraulic tubes, wherein the proportional valve is mounted on the carrier and an on-off valve is arranged on the drive portion, which connects the hydraulic tubes with the proportional valve or disconnects them from the same at option.

Abstract: Hydraulic lifting device for battery-operated industrial trucks, with at least one hydraulic lifting cylinder, a hydraulic pump working as a pump in the load lifting operation mode, supplying the lifting cylinder with pressure medium and working as a motor in the operation mode of lowering the load, driven by the pressure medium that is displaced by the lifting cylinder, an electric machine coupled to the hydraulic pump, working as an electric motor in the load lifting mode and working as a generator in the mode of lowering the load, a rotation speed control device for the electric machine, the electric machine being controllable in its speed by the rotation speed control device, depending upon the actuation of a set-point transmitter, a lifting valve arrangement in a lifting branch leading to the lifting cylinder, a lowering branch between the lifting cylinder and a connection between a check valve and an entry of the hydraulic pump, a volume flow delimiter in the lowering branch, a bypass valve arrangement

Abstract: Device for the emergency lowering of a load carrying means for a stacker truck, in particular a reach-type forklift truck, with a valve arrangement accommodated in a valve block, via which the inflow and outflow of a hydraulic means is regulated to and from a lift cylinder for the load carrying means, with a bypass between the lift cylinder and a tank, with a barrier element in the bypass and an actuating device containing a cable which may be actuated by an operator, and by means of which the barrier element may be brought into the open position, the bypass being formed by a bypass branch in the valve block, a screw-shaped barrier element with a male thread portion being screwed into a threaded bore of the valve block and, in the fully screwed-in position, closes off the bypass branch, a cable transmitting a torque being rotationally fixedly connected with one end to the barrier element and a handle for turning the cable being attached to the other end of the cable.

Abstract: Hydraulic lifting device for battery-operated industrial trucks, with at least one hydraulic lifting cylinder, a hydraulic pump working as a pump in the load lifting operation mode, supplying the lifting cylinder with pressure medium and working as a motor in the operation mode of lowering the load, driven by the pressure medium that is displaced by the lifting cylinder, an electric machine coupled to the hydraulic pump, working as an electric motor in the load lifting mode and working as a generator in the mode of lowering the load, a rotation speed control device for the electric machine, the electric machine being controllable in its speed by the rotation speed control device, depending upon the actuation of a set-point transmitter, a lifting valve arrangement in a lifting branch leading to the lifting cylinder, a lowering branch between the lifting cylinder and a connection between a check valve and an entry of the hydraulic pump, a volume flow delimiter in the lowering branch, a bypass valve arrangement

Abstract: Method for the adjustment of a control current of current-controlled, hysteresis-affected hydraulic valves for the actuation of individual hydraulic functions of industrial trucks, the control current being generated in an electronic control device according to a manually pre-set transmitter signal, characterised by the following steps for each hydraulic function which is controlled by a hydraulic valve, an average characteristic line I=f(Q) is determined by experiments or via calculation, in which I is the control current and Q is the volume flux of the hydraulic medium flowing through the hydraulic valve, the specific characteristic line Ires=f(Q) is measured for each individual hydraulic valve, and a first average control current value for a predetermined volume flux value is determined from the characteristic line values, between the first average control current value and a second average control current value, which is derived from the determined characteristic line I=f(Q) at the pre-set volume flux val