Jungheinrich Aktiengesellschaft

Thomas Stolten

Michael Knieriem

Nis-Georg Nissen

Uwe Allerding

Christoph Behncke

Matthias Düwel

Christian Puke

Jens Glaeske

Hans-Peter Arp

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

Industrial truck, hydraulic system for an industrial truck and method for operating a hydraulic system

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

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.

Lifting device for an industrial truck as well as an industrial truck of this type

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.

Device for the emergency lowering of a load-carrying means for a stacker truck

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.res=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 value, the difference is formed and a constant is added, and the control current correction value thus determined is attached to the case of the individual hydraulic valve as a code, upon assembly of the hydraulic valve, the code is read out and memorised into the control device, for the purpose of correction of the respective control current, when the hydraulic function is triggered, for the control current correction value according to the characteristic line I=f(Q) laid down in the control device.

Method for the adjustment of the control current of current-controlled hydraulic valves

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 that connects an exit of the hydraulic pump with the tank, and at least one further hydraulic consumer, which can be supplied by the hydraulic pump via an assigned control valve, wherein the lifting valve in the lifting branch is disposed downstream from the branching of a conduit to the secondary consumer and the conduit is connectable to the tank via a pressure balance on the upstream side of the control valve.

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Tremsbüttel, Germany

Thomas Stolten