EP2322465A1

EP2322465A1 - Load-lifting system

Info

Publication number: EP2322465A1
Application number: EP09175971A
Authority: EP
Inventors: Thomas Linder; Torben Nielsen
Original assignee: Atlet AB
Current assignee: Atlet AB
Priority date: 2009-11-13
Filing date: 2009-11-13
Publication date: 2011-05-18
Anticipated expiration: 2029-11-13
Also published as: EP2322465B1

Abstract

A load-lifting system (10) comprising a first (1a) and a second (1b) part that are displaceable in relation to each other by means of a guide roller arrangement (20) is disclosed. The load-lifting system (10) comprises
a stub shaft (21) arranged on the second part (1b);
a roller bearing (22) mounted on the stub shaft (21), the roller bearing comprising an outer rotatable bearing element (22a) forming a guide roller, arranged to be in contact with a channel (2a) in the first part; and
at least one displaceable shim (23), arranged on the stub shaft (21) between the second part (1b) and the roller bearing (22), for displacing the roller bearing (22) laterally relative the second part (1b), the displaceable shim (23) being radially insertable to the stub shaft (21), to partially surround the stub shaft (21).
A corresponding method for adjusting the load-lifting system (10) is also disclosed.

Description

Technical Field

The present invention relates to a load-lifting system and a displaceable shim arranged in such a system. The present invention also relates to a method for adjusting a load-lifting system.

Background of the Invention

In load-lifting systems comprising two parts that are displaceable in relation to each other, there is conventionally a guide means arranged between the two displaceable parts. For example, industrial trucks conventionally comprises a load-lifting system, such as mast uprights that are displaceable in relation to each other. Naturally, the guide means between the displaceable parts of an industrial truck is subject to wearing and therefore, or for adjustment or readjustment due to for example variations in construction, the system must be adjusted periodically. Shims are conventionally used for such adjustments. Shims are added and/or removed depending on the type of adjustment.
In industrial trucks shims are moreover used to obtain a sufficient play between two parts that are displaceable in relation to each other, so that the friction is not too high or the gap between the parts too large. Therefore shims are added or removed to adjust the play.
A problem when performing the above mentioned adjustments is that the entire mast system of an industrial truck must be disassembled to be able to exchange, add or remove a shim. This procedure is both costly and inefficient, since important operating time is lost. It may also be hazardous to disassemble parts of a load-lifting system, that are often heavy and cumbersome.
In an attempt to simplify the adjustment US 4 354 579 teaches an apparatus for guiding lift truck mast segments, comprising a guide roller arranged between two mast segments that are displaceable in relation to each other. The proposed solution in US 4 354 579 is to provide an arrangement wherein inter alia a stub shaft is arranged on a plate which is fastened by fasteners.
Although providing an arrangement which is easier and more efficient to adjust than conventional arrangements, there are still several steps of execution such as loosening and fastening bolts, removing parts to reach other parts or areas etc, in the solution provided in US 4 354 579 . For many types of industrial trucks the solution provided in US 4 354 579 still requires that the entire mast system is dissassambled to be able to perform the adjustments. Therefore, there is room for improvement, by providing an improved load-lifting system.

Summary of the invention

In view of the above, a general object of the present invention is to provide an improved load-lifting system. This and other objects are achieved through a load-lifting system, an open shim and a method for adjusting a load-lifting system according to the appended claims.
According to an aspect of the present invention there is provided a load-lifting system comprising a first and a second part that are displaceable in relation to each other by means of a guide roller arrangement comprising
a stub shaft arranged on the second part;
a roller bearing mounted on the stub shaft, the roller bearing comprising an outer rotatable bearing element forming a guide roller, arranged to be in contact with a channel in the first part; and
at least one displaceable shim, arranged on the stub shaft between the second part and the roller bearing, for displacing the roller bearing laterally relative the second part, the displaceable shim being radially insertable to the stub shaft, to partially surround the stub shaft.
The first and second part may be any parts of a load-lifting system that are displaceable in relation to each other, such as uprights, horizontal reach movements, or tilted upright movements.
By a roller bearing may mean any object comprising a rotatable surface to be arranged in contact with a displaceable part. Examples of a roller bearing may be a conventional ball or roller bearing comprising an inner and outer race and a set of balls or cylinders arranged therebetween, whereby two parts, such as the stub shaft and the second part of the load-lifting system, may be moved in relation to each other with very little resistance.
By laterally displacing means displacement in the axial direction of the stub shaft.
By radially insertable means that the displaceable shim is insertable to the stub shaft across the axial direction of the stub shaft.
The present invention is based on the understanding that adjustment of the load-lifting system, such as for compensating for variations in construction, or wear factors, may be made by adding or removing shims to or from the stub shaft. Further, the displaceable shims are radially insertable to the shaft, with the result that a shim may be added, or removed without disassembly of any parts of the load-lifting system. In the case that a displaceable shim is to be added, it may simply be snapped on to the stub shaft. If a displaceable shim is to be removed it is pulled from its place on the stub shaft. That is, the steps of execution for adjusting the load-lifting system are reduced and simplified in comparison to prior art. In addition, an optimal play between the two parts that are displaceable in relation to each other may be obtained in an easy manner. Since the system do not have to be disassembled when adding or removing a displaceable shim the play may be adjusted frequently and as soon as needed for obtaining an optimal friction and a sufficient gap between the parts of the system, which otherwise would tend to be left unchanged if the play is operational but not optimal. Hence, a system with a higher quality and performance may be obtained with the solution of the present invention.
Further, to facilitate mounting or dismounting of the displaceable shim to or from the stub shaft, and for the displaceable shim to be fixedly arranged on the stub shaft the displaceable shim may inwardly form an open ring. The inward shape does however not control the outer form of the displaceable shim.
In addition, the displaceable shim, as previously mentioned, provide a simple and cost-effective handling. Especially adjustments by means of the displaceable shim is rendered cheap and easy..
The outer circumference of the displaceable shim may correspond to the inward form of a ring like traditional shims. However, alternative shapes of the outer circumference, such as oblique, triangular or square, may be possible or even advantageous. Certain shapes of the outer circumference may for example facilitate gripping of the displaceable shim.
Moreover, an opening of said displaceable shim may be smaller than a diameter of said stub shaft, whereby the displaceable shim may be snapped on to the stub shaft, and be securely arranged on the shaft without falling off.
Alternatively, e.g. with a larger opening, a first displaceable shim and a second displaceable shim may be joined by a joint, and the two displaceable shims may be arranged on different sides of the stub shaft, by closing the two displaceable shim arrangement by means of the joint. Two displaceable shims may also be joined by means of for example barbs or Velcro tape. These arrangement may especially be advantageous with an increased displaceable shim thickness.
Further, the opening size may depend on for example the material of the displaceable shim. The displaceable shim may be made of a resilient material, preferably spring steel. By using a resilient material the displaceable shim may be easily snapped on to the stub shaft. The opening size may moreover be made smaller with a resilient material, yet return to the original shape after insertion to the shaft, whereby the displaceable shim may be fixedly arranged on the stub shaft. Another example of material is plastic.
Moreover, the displaceable shim may have a thickness in the range between 0.05 and 2 mm, and preferably between 0.2 and 1 mm, and most preferably the thickness may be about 0.5 mm. A shim may be made having a thickness that compensate for for example variations in construction by itself, or a plurality of shims may be arranged on the shaft to together compensate for such or other factors.
Alternatively, the displaceable shim may have a larger thickness, such as 5 millimeters or more. In this way the displaceable shim may form also the basic shim arrangement on the stub shaft. A thicker displaceable shim may for example be advantageous if the displaceable shim is made of a light material, such as plastic. Such thicker shims may be used in the same way as discussed in the foregoing, where simple adjustments are rendered possible by e.g. exchanging a first shim with a slightly thicker or slightly narrower second shim. Accordingly, a set of shims with small thickness increments may be used to obtain the intended thickness for any particular situation.
Further, the displaceable shim may comprise an operatingmeans, the operating means preferably protruding away from said direction of insertion for facilitating insertion and/or removal of the displaceable shim. The operating means may be a flat ear, or have alternative shapes, depending on what tool to be used when inserting or removing the displaceable shim. The operating means may be integrated to the displaceable shim, or a detached part that may be fastened to the shim when needed. For example, pliers may be used to keep the operating means during insertion or removal of the displaceable shim. Alternatively, the operating means may protrude in a direction such that the operating means may be passed over the stub shaft before the displaceable shim. For example, the operating means may be formed as two protruding parts that may be pulled over the stub shaft to thereby arrange the displaceable shim on the stub shaft.
Furthermore, the operating means may comprise an aperture. An aperture may further facilitate especially removal of the operating shim, by allowing a hook to be inserted to the aperture before pulling.
In addition, the aperture may be used for attaching a displaceable shim to the stub shaft by means of for example inserting a screw to the aperture. Attachment through the aperture may be used as the only means of attachment or as a complementary attachment depending on the form of the displaceable shim.
According to another aspect of the present invention, there is provided a method for adjusting a load-lifting system comprising a first and a second part that are displaceable in relation to each other by means of a guide roller arrangement comprising
a stub shaft arranged on the second part;
a roller bearing mounted on the stub shaft, the roller bearing comprising an outer rotatable bearing element forming a guide roller, arranged to be in contact with a channel in the first part; and
at least one displaceable shim, arranged on the stub shaft between the second part and the roller bearing, for displacing the roller bearing laterally relative the second part, the displaceable shim being radially insertable to the stub shaft, to partially surround the stub shaft, the method comprising the steps of:

separating the first and second part without disassembling the load-lifting system; and
inserting the displaceable shim to said stub shaft radially, between the first and second part.

Hence, the present invention facilitates adjusting of a load-lifting system by allowing exchange, addition or removal of a displaceable shim with only a few execution steps. For example, if inserting a displaceable shim, only two steps are necessary, none of the steps requiring disassembling of the load-lifting system. There is for example no need to remove or add fasteners when adjusting the system. The method is advantageous since it saves time and with that also money. The method moreover renders adjusting of the system simplified, and it may therefore be performed by individuals without any specific skills. It is advantageous that the system may be adjusted by the users of the system and not only the manufacturer or experts, since especially wear factors but also variations in construction may appear after shorter or longer usage of the load-lifting system in the industry.
According to another aspect of the present invention, there is provided a displaceable shim which is partly formed as a ring comprising an opening allowing radial insertion of the displaceable shim to a shaft. The displaceable shim may typically be c-shaped but other shapes are feasible. Many of the advantages relating to the load-lifting system is also valid for the displaceable shim. Moreover, such a displaceable shim may be used with advantage in other applications comprising a stub shaft than load-lifting systems.
According to yet another aspect of the present invention there is provided an industrial truck comprising the load-lifting system. An industrial truck may comprise several load-lifting systems, whereby improved simplified adjustment of such systems is advantageous.

Brief description of the drawings

In the following, embodiments of the present invention will be described in detail, with reference to the accompanying, exemplifying drawings on which:

Figure 1 is a perspective view of a load-lifting system according to the present invention.
Figure 2 is an exploded view of a guide roller arrangement according to the present invention.
Figure 3 is a perspective view of a displaceable shim.
Figure 4 is a perspective view of an industrial fork-lift truck.

Detailed description of preferred embodiments

In the following examples the present invention will be described in relation to a load-lifting system 10 wherein the displaceable parts are uprights, although the same may be advantageously applied also for other parts, such as a reach carriage, telescopic forks, or horizontal or tilted uprights.
In fig. 1 three uprights 1 a-c are illustrated, that are displaceable in relation to each other. The first upright 1 a is stationary, whereas the second upright 1 b is axially displaceable in relation to the first upright 1 a, and the third upright 1 c is axially displaceable in relation to the second upright 1 b. At least the first 1 a and second 1 b upright forms a channel in the longitudinal direction, the channel opening of the first upright 1 a being directed toward the second upright 1 b, and the channel opening of the second upright 1 b being directed toward the third upright 1 c. Here, the second 1 b and third 1 c uprights have I-beam and/or U-beam cross-sections for supporting the arrangement against the neighbouring upright. A guide roller 20a is arranged in the channel 2a of the first upright 1 a between the first and second upright, and another guide roller 20b is arranged in the channel 2b of the second upright 1 b between the second 1 b and third 1 c upright, respectively. The guide roller arrangement 20 is described in more detail in relation to fig. 2.
In the initial position, the three uprights are arranged essentially in parallel, side by side, the channel of each upright facing the corresponding neighboring upright. When extending telescopically, the second upright 1 b is axially displaced in relation to the first upright 1 a by means of the guide roller arrangement 20a which is arranged therebetween. Simultaneously, the third upright 1 c is axially displaced in relation to the second upright 1 b by means of the guide roller arrangement 20b which is arranged therebetween. For simplicity, the following description will relate mainly to two uprights, the first 1 a and the second 1 b upright and the corresponding guide roller arrangement 20a.
As can be seen in the exploded view of fig. 2, the guide roller arrangement 20 comprises a stub shaft 21, which extends horizontally between neighboring uprights, such as between the second 1 b and first 1 a upright. A roller bearing 22 comprises an outer rotatable element forming a guide roller 22a and an inner element 22b that is arranged on the stub shaft 21. There is a closed shim 24 arranged between the roller bearing 22 and the second upright 1 b. Further, a displaceable shim 23 is arranged on the stub shaft 21 between the closed shim 24 and the second upright 1 b. The displaceable shim 23 is here formed as an open ring, like a c-shape. The diameter of the opening 27 is slightly smaller than the diameter of the stub shaft 21. In the illustrated example the displaceable shim 23 further comprises an operating means 25, here in form of a flat ear with an aperture 26. The displaceable shim 23 is preferably made of a resilient material, such as spring steel that return to the original shape after bending.
In operation, the guide roller 22a of the roller bearing 22, arranged in contact with the channel 2a of the first upright 1 a in which the guide roller 20a is arranged, rotates as the displaceable second upright 1 b is axially displaced in relation to the stationary first upright 1 a. Variations in construction may be seen in an early phase, which variations need to be compensated for, often already at the manufacturing site. Later on, adjustments must be made due to wearing of the load-lifting system. The play between the first 1 a and second 1 b uprights may be adjusted when required for an optimal play.
The closed shim is mounted to the guide roller arrangement 20 already in the construction phase. The displaceable shim however may be mounted thereafter to for example compensate for mentioned variations in construction, or for wearing factors of for example the guide roller 22 or beam profile during use of the system. Alternatively, displaceable shims 23 are arranged to the guide roller arrangement 20 from the beginning. A displaceable shim 23 may however be easily arranged on the stub shaft 21 also after assemblement of the complete system by snapping it over the stub shaft 21. A tool may be used to grip the protruding operating means 25 to facilitate insertion, while a hook may be inserted in the aperture 26 of the operating means 25 to facilitate removal of the displaceable shim 23 when needed, for example for exchangment of an already inserted displaceable shim 23. The fact that the displaceable shim 23 is inwardly ring formed and has an opening renders it easy to remove from or add to the stub shaft 21, especially since a resilient material is used.
Fig. 3 illustrates an example of a displaceable shim 23 according to the present invention. In the illustrated example the displaceable shim is c-shaped, inwardly 28 and outwardly 29 forming a ring. The diameter of the opening 27 is made slightly smaller than the diameter of the stub shaft onto which the displaceable shim 23 is to be arranged. A operating means 25, here in the form of a flat ear is integrated to the displaceable shim, which ear comprises a round aperture adapted to receive a hook which may simplify especially removal of the displaceable shim 23. Such a displaceable shim 23 may be used in any system where it may be inserted to a stub shaft.
Fig. 4 illustrates an example of a load-lifting system of the present invention. The load-lifting system is here an industrial fork-lift truck 30 comprising three pairs of uprights 1 a-c that forms a frame that is telescopically displaceable. The first pair 1 a is stationary.The second pair 1 b is axially displaceable in relation to the first stationary pair 1 a, and the third pair 1 c in relation to the second pair 1 b, respectively. A fork carriage 31 is arranged on the third upright 1c, and is axially displacable along the third upright 1 c, from bottom to top. In the non-extended position all the three pairs of uprights 1 a-c are arranged side by side, while, in the most extended position, the uprights are telescopically displaced so that the third pair of uprights1 c are arranged on top of the second pair of uprights 1 b, and the second pair 1 b on top of the first pair 1 a of uprights. In this manner, the fork carriage 31 may be elevated along with telescopical displacement of the uprights 1 a-c from the bottom of the truck 30 to the top, where full extension is reached, to for example lift a load arranged thereon. First, the fork carriage 31 is free lifted along the third upright 1 c, and thereafter, the second 1 b and third 1 c uprights are simultaneously displaced in the axial direction. Likewise, the uprights can return to the initial position from the most extended position to lower the fork carriage 31 again.
It can be seen that there are two guide roller arrangements arranged between each of the first 1 a and second 1 b uprights, as well as two guide rollers between each of the second 1 b and third 1 c uprights. In addition, there are guide rollers between the third uprights 1 c and the fork carriage 31.
The person skilled in the art realizes that the present invention is not limited to the preferred embodiments. For example the displaceable shim may have various open forms, for example square or oblique, with and without operating means and be made of various materials, such as plastic. The guide roller may have various forms, such as oval or ball formed, and there are other types of load-lifting systems, such that stationary load-lifting systems, etc.
Such and other obvious modifications must be considered to be within the scope of the present invention, as it is defined by the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word "comprising" does not exclude the presence of other elements or steps than those listed in the claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Further, a single unit may perform the functions of several means recited in the claims.

Claims

A load-lifting system (10) comprising a first (1a) and a second (1 b) part that are displaceable in relation to each other by means of a guide roller arrangement (20) comprising
a stub shaft (21) arranged on said second part (1 b);
a roller bearing (22) mounted on said stub shaft, the roller bearing comprising an outer rotatable bearing element (22a) forming a guide roller, arranged to be in contact with a channel (2a) in said first part (1 a); and
at least one displaceable shim (23), arranged on said stub shaft (21) between said second part (1 b) and said roller bearing (22), for displacing said roller bearing (22) laterally relative said second part (1 b), said displaceable shim (23) being radially insertable to said stub shaft (21), to partially surround the stub shaft (21).
The load-lifting system according to claim 1, wherein said displaceable shim (23) inwardly forms an open ring.
The load-lifting system according to any of the preceding claims, wherein an opening of said displaceable shim (23) is smaller than a diameter of said stub shaft (21).
The load-lifting system according to any of the preceding claims, wherein said displaceable shim (23) is made of a resilient material, preferably spring steel.
The load-lifting system according to any of the preceding claims, wherein said displaceable shim (23) has a thickness in the range between 0,05 and 2 mm, preferably in the range between 0.2 and 1 mm, and most preferably about 0.5 mm.
The load-lifting system according to any of the preceding claims, wherein said displaceable shim (23) comprises an operating means (25), said operating means (25) preferably protruding away from said direction of insertion.
The load-lifting system according to claim 6, wherein said operating means (25) comprises an aperture (26).
A method for adjusting a load-lifting system (10) comprising a first (1 a) and a second (1 b) part that are displaceable in relation to each other by means of a guide roller arrangement (20) comprising
a stub shaft (21) arranged on said second part (1 b);
a roller bearing (22) mounted on said stub shaft (21), the roller bearing (22) comprising an outer rotatable bearing element (22a) forming a guide roller, arranged to be in contact with a channel (2a) in said first part (1 a); and
at least one displaceable shim (23), arranged on said stub shaft (21) between said second part (1 b) and said roller bearing (22), for displacing said roller bearing (22) laterally relative said second part (1 b), said displaceable shim (23) being radially insertable to said stub shaft (21), to partially surround the stub shaft (21), the method comprising the steps of:
separating said first (1 a) and second (1 b) part without disassembling said load-lifting system; and

inserting said displaceable shim (23) to said stub shaft (21) radially, between said first (1 a) and second (1 b) part.
A displaceable shim (23) which is partly formed as a ring comprising an opening (27) allowing radial insertion of said displaceable shim (23) to a shaft.
The displaceable shim according to claim 9, wherein said displaceable shim (23) is made of a resilient material, preferably spring steel.
The displaceable shim according to any of claim 9 to 10, wherein said displaceable shim (23) has a thickness in the range between 0.05 and 2 mm, preferably in the range between 0.2 and 1 mm, and most preferably about 0.5 mm.
The displaceable shim according to any of claims 9 to 11, comprising an operating means (25),said operating means (25) preferably protruding away from said direction of insertion.
The displaceable shim according to claim 13, wherein said operating means (25) comprises an aperture (26).
An industrial truck (30) comprising the load-lifting system according to claim 1-7.