LIFTING MAST FOR AN INDUSTRIAL TRUCK WITH TWO LOAD CARRYING DEVICES

Description

[0001] The present invention relates to a lifting mast for an industrial truck with two load-bearing elements. The lifting mast comprises a pair of outer mast profiles and a pair of inner mast profiles, which are movably arranged within the outer mast profiles and are height-adjustable via a mast lifting unit.

[0002] EP 2 159 186 A1 discloses an industrial truck with a lifting mast featuring two independently operable load-bearing elements. A lower load-bearing element is raised via a centrally positioned short-stroke cylinder. The other load-bearing element is height-adjusted in a lifting mast with inner and outer mast profiles, using a free lift and a mast lift.

[0003] The invention is based on the object of providing a lifting mast for an industrial truck which enables the operation of two load-bearing devices using simple means.

[0004] According to the invention, the object is achieved by a lifting mast having the features of claim 1. Advantageous embodiments form the subject matter of the subclaims.

[0005] The lifting mast according to the invention has the features of claim 1. The lifting mast is provided and intended for an industrial truck with two load-bearing means, each of the load-bearing means having two forks. The lifting mast consists of a pair of outer mast profiles and a pair of inner mast profiles, which are movably arranged in the outer mast profiles and are height-adjustable via a mast lifting unit in the outer mast profiles. The outer mast profiles can also be characterized as vehicle-fixed mast profiles. Furthermore, a mast lifting unit is provided, with which the height of the inner mast profiles can be adjusted. A free lifting unit is also provided.

[0006] According to the invention, a lower load-bearing element is connected to the inner mast profiles and is height-adjustable via the mast lifting unit. An upper load-bearing element is mounted in the inner mast profile for height adjustment and is height-adjustable via the free-lift unit. The lifting mast according to the invention has the advantage that very few design changes are required compared to a conventional lifting mast, in which a single load-bearing element is height-adjustable via the mast lifting unit and free-lift unit.

[0007] In a preferred embodiment, the free lift unit has a lifting cylinder located between the mast profiles. The lifting cylinder can, for example, have a chain that is attached to the upper load-bearing means. When reference is made to upper and lower load-bearing means in the context of the present invention, this does not mean that one load-bearing means is always arranged above the other. Rather, the case is also included that both load-bearing means are arranged at the same height. In this context, upper and lower load-bearing means are to be understood such that the load-bearing means is suitable for being moved into an upper position relative to the other load-bearing means. The lower load-bearing means is characterized in this sense in that it cannot be moved into a position above the other load-bearing means.

[0008] In a preferred embodiment, the lifting cylinder of the free-lift unit is arranged on a crossbeam between the inner mast profiles. This means that when the inner mast profiles are raised by the mast lifting unit, the lifting cylinder of the free-lift unit is also raised. The particular advantage of this embodiment is that if the upper load-bearing element has been moved into a position relative to the lower load-bearing element, this distance is maintained when the lower load-bearing element is raised.

[0009] In a preferred embodiment, the mast lifting unit has one or two lifting cylinders arranged laterally on the mast profiles. The lifting cylinders of the mast lifting unit are preferably arranged laterally close to the mast profiles, out of the field of vision through the lifting mast.

[0010] In a preferred embodiment, the free lift and mast lift units can be hydraulically controlled independently of each other. Hydraulically independent control means that a driver can control both load-bearing elements independently of each other, with the upper load-bearing element being raised together with the lower load-bearing element. Unlike conventional lifting masts, there is no automatic transition between free lift and mast lift, so these functions are hydraulically independent.

[0011] In a preferred embodiment, the forks of the load-bearing means are arranged side by side in a lowered state. Preferably, the forks of one load-bearing means are both arranged within the forks of the other load-bearing means. Here, it has proven advantageous to arrange the lower load-bearing means, which is connected to the inner profiles, within the upper load-bearing means.

[0012] A preferred embodiment is explained in the following figures. It shows: Fig. 1 the lifting frame according to the invention in three views with lowered load-bearing means, Fig. 2 the load-bearing means from Figure 1 with the upper load-bearing means raised and Fig. 3upper and lower load-bearing means raised.

[0013] Figure 1shows a mast 10 with an outer pair of mast profiles 12a, 12b. The outer mast profiles 12a, 12b are connected to each other via a crossbeam 14. The crossbeam 14 has two connection areas 16a, 16b, which are connected to each other via a crossbeam 18. At their lower end, the outer mast profiles 12a, 12b are connected to each other by a lower crossbeam 20. The mast with its outer mast profiles 12 is additionally stabilized by a middle crossbeam 22. This is usually located at the level of the drive part of the industrial truck so that the middle crossbeam 22 does not obstruct the view. The inner mast profiles 24a, 24b are arranged within the outer mast profiles 12. The inner mast profiles 24 are mounted in the outer mast profiles 12 in a height-adjustable manner, for example via rollers.

[0014] In Figure 1Also clearly visible in the center of the mast is hydraulic cylinder 26, which has a chain roller at its free end. The chain of hydraulic cylinder 26 is firmly connected to the hydraulic cylinder 26 and its other end to the upper load-bearing device.

[0015] On the right side of the Figure 1 A view of the load-bearing elements 28 and 30 is shown. The load-bearing element 28 is arranged on two crossbeams 32a, 32b. A pair of forks 34a and 34b are fixedly mounted on the crossbeams 32a, 32b. The crossbeams 32 are slidably mounted in the inner mast profile 24.

[0016] The load-bearing means 30 is arranged on a back plate 36, wherein the back plate 36 is firmly connected to the inner mast profiles 24a, 24b.

[0017] Figure 2shows the operation when lifting the upper load-bearing element 28. The lifting cylinder 26, which is intended for the free lift, extends and takes the upper load-bearing element 28 with it via the chain. The lower load-bearing element 30, which is connected to the inner mast profile, remains in its lowered position.

[0018] Figure 2 shows on the left side the inner hydraulic cylinders 38, which are used to lift the mast, raising the inner mast profile relative to the outer mast profile.

[0019] Figure 3 shows the lifting frame according to the invention with both load-bearing elements raised. The lower load-bearing element 30 is raised by the mast lift via the lifting cylinders 38. In Figure 3 The inner mast profile 24 protrudes from the outer mast profile 12. The lower load-bearing element 30 moves with the inner mast profile 24. The upper load-bearing element 28 is raised via the central lifting cylinder 26. This can be clearly seen in Figure 3also that the central lifting cylinder 26 is also raised together with the inner mast profile, so that the distance between the upper load-bearing means 28 and the lower load-bearing means 30 is maintained.

[0020] A particular advantage of the illustrated mast is that its design is virtually identical to that of a conventional two-mast mast for a single load-bearing device. The only structural differences are the lower load-bearing device 30, and the lifting cylinders 26 and 38 are hydraulically coupled to ensure the smoothest possible transition from free lift to mast lift. Reference symbol

[0021] 10 Mast 12 a / b outer mast profiles 14 Crossbeam 16 a / b connection area 18 Crossbeam 20 Crossbeam 22 Crossbeam 24 a / b inner mast profiles 26 Hydraulic cylinder 28 Load-bearing device 30 Load-bearing device 32 a / b Crossbeams 34 a / b Forks 36 Back plate 38 Hydraulic cylinder

Claims

1. Lifting mast (10) for an industrial truck with two load-carrying means (28, 30), which has a pair of outer mast profiles (12a, 12b) and a pair of inner mast profiles (24a, 24b), which are arranged movably in the outer mast profiles (12a, 12b) and are height-adjustable via a mast lifting unit, a free-lifting unit being provided, characterised in that a lower load-bearing means (30) is connected to the inner mast profiles (24a, 24b) and can be adjusted in height via the mast lifting unit and an upper load-bearing means (28) is mounted in the inner mast profiles (24a, 24b) and can be adjusted in height via the free-lifting unit.

2. Lifting mast (10) according to claim 1, characterised in that the free-lifting unit comprises a lifting cylinder (26) standing between the mast profiles.

3. Lifting mast (10) according to claim 2, characterised in that the lifting cylinder (26) of the free-lifting unit has a chain which is fastened to the upper load-bearing means (28).

4. Lifting mast (10) according to claim 2 or 3, characterised in that the lifting cylinder (26) of the free-lifting unit is arranged on a transverse traverse between the inner mast profiles (24a, 24b) and is also lifted when the inner mast profiles (24a, 24b) are lifted by the mast lifting unit.

5. Lifting mast (10) according to one of claims 1 to 4, characterised in that the mast lifting unit has one or two lifting cylinders (26, 38) which are arranged laterally on mast profiles.

6. Lifting mast (10) according to one of claims 1 to 5, characterised in that the free-lifting and mast-lifting units can be hydraulically controlled independently.

7. Lifting mast (10) according to one of claims 1 to 6, characterised in that, in the lowered state, the forks (34a, 34b) of the load-bearing means (28, 30) are arranged next to one another.

8. Lifting mast (10) according to claim 7, characterised in that the forks of one load-carrying means are both located inside the forks of the other load-carrying means.