GB2086843A

GB2086843A - Lifting frame for a lifting truck

Info

Publication number: GB2086843A
Application number: GB8128453A
Authority: GB
Original assignee: Jungheinrich Unternehmensverwaltung KG
Current assignee: Jungheinrich AG
Priority date: 1980-11-06
Filing date: 1981-09-21
Publication date: 1982-05-19
Also published as: DE3041910C2; DE3041910A1; GB2086843B

Abstract

In a lifting truck comprising a stationary column section 4 an extensible column section 5, 6 and a load carriage movable along said extensible column section, said column sections have side struts 27-32 consisting of I-sections receiving guiding rollers 53-62 and the side struts are connected by a plurality of transverse hollow struts e.g. 23. Laterally disposed rear stiffeners 50, 51 are provided behind the transverse struts. Channel members e.g. 41 are also provided. <IMAGE>

Description

SPECIFICATION Lifting frame for a lifting truck This invention relates to a lifting frame for a lifting truck comprising a load carrier which is movable along the lifting frame, a stationary column section, at least one extensible column section, and a load carriage movable along said extensible column section and adapted to carry the load carrier, wherein said column sections have profiled side struts consisting of I-sections formed with profiled openings for forward guiding rollers and lateral guiding rollers, the side struts are connected by a plurality of transverse struts, lateral rear stiffeners are provided on the rear side of the column and spaced behind the transverse structs, and channel members for receiving the lateral guiding rollers are provided in the central portion behind the transverse struts.

In such known lifting frames, the side struts of different column sections are spaced different distances apart from the transverse struts and connecting members extending at right angles to the transverse plane of the column are provided between the transverse struts and the side struts.

These connecting members progressively decrease in length in the direction from the stationary column section to the inwardly disposed column sections, so that all column sections terminate substantially in the same plane on the forward face of the column. Such lifting frame has different strengths, particularly different torsional strengths, in different column sections. In the known design the rear stiffeners are also set off by connecting members and consist of steel sections which are small in cross-section and intended to take up only tensile stresses, particularly of square sections.

That known design has an adequate strength but will be twisted to some extent when used at high stacks and with an extended lifting frame; this will render lateral stacking more difficult and require a careful attention by the operator.

It is also known to provide the stationary column section with transverse struts, which consist of hollow sections relatively small in crosssection. Transverse struts consisting of flat sections are provided in inner column sections so that the lifting frame is relatively flat.

In the known lifting frames, the lateral guidance is provided as a single-line guidance in that lateral guiding rollers of adjacent column sections run in the channel members of the central portion, For this reason a relatively large overlap of the column sections is required for an adequate lateral guidance.

It will be understood that a lifting frame is provided in known manner with at least one lifting cylinder-piston device and chains trained around reversing sprockets are provided between the column sections. The load carriage is also correspondingly arranged and guided so that the load carriage is vertically movable with a plurality of column sections, possibly in conjection with a simultaneous extension of the lifting frame. The term "load carrier" on the load carriage includes the provision of cages, load-carrying forks and other load-handling means on a carriage which is vertically movable along a column section of the lifting frame.

German Early Disclosure 28 11 964 discloses a lifting frame that is designed in accordance with the above considerations. In that known lifting frame the side struts consist of S-sections, which are connected by central transverse struts. Those of said transverse struts which are associated with outer column sections are connected to the side struts, consisting of S-sections, by connecting members which extend at right angles to the transverse dimension of the lifting frame so that the entire arrangement has in plan view the configuration of a U having legs which comprise the connecting members and increase in length towards the stationary column section. This arrangement results in undesired force actions, particularly owing to the considerable lever arms obtained relative to the central portions and with the optional connecting members interposed.

Whereas the S-sections afford advantages as regards the arrangement of the forward guiding rollers, they must have large dimensions.

As regards the forward guiding rollers the known arrangement is included from the aspect that the load carrier exerts a forward torque on the lifting frame and said forward torque must be taken up so that with respect to each column section that is extensible above the adjacent column section there will be a support toward the rear at the lower end of the overlap and a support in the forward direction at the upper end of the overlap. Particularly in lifting frames for high-level lifting trucks, the stability is decisive and the torsional strength is also significant because substantial loads are turned on a high level and are pushed laterally beyond the contour of the column.

For this reason it is known to use column sections which have a relatively large transverse dimension and oblique side walls that extend outwardly and forwardly in order to ensure that the column will have a high torsional strength even when it is extended. But that design is inconsistent with the requirement for a relatively flat lifting frame so that a truck having a relatively small wheelbase can be used. This is important for the manoeuvrability particularly outside narrow passages between racks.

For this reason it is an object of the invention to provide an improved lifting truck which is of the kind described first hereinbefore and while involving only a small structurai expenditure has a high stability and particularly a high torsional strength whereas the lifting frame as a whole should have a small depth.

This object is accomplished in accordance with the invention in that at least those transverse struts which are associated with the extensible column sections consist of transverse hollow sections, the transverse struts extend as far as to the outside of the respective column section, the side struts consist of I-sections and are provided directly on the forward face of the transverse struts as forward stiffeners, and the rear stiffeners on at least one side are directly provided on the rear side of the transverse struts and consist of section members for guiding lateral guiding rollers. This design results in a compact lifting frame having column sections which have a considerably higher stability and torsional strength than are obtained in known designs. The side struts may be weaker than in known designs because they are directly connected to the transverse hollow sections.The section beams provided as rear stiffeners on the rear may be relatively flat and owing to their sectional shape contribute to the stability of the compact arrangement. Besides, a single-line lateral guidance is provided and the lateral guiding rollers between adjacent column sections are offset also in the direction of the width of the column so that a smaller overlap will be permissible when the lifting frame has been extended and the lifting frame can be utilized to a larger extent.

The distance between the forward and rear stiffeners, which are directly secured to the transverse struts, is desirably determined by the ends of the transverse struts, which consist of hollow box sections.

One rear stiffener at least on one side desirably consists of a rearwardly open channel member, This ensures a flat arrangement having a high stability and torsional strength. One rear stiffener on the side opposite to the channel member is bar-shaped and comprises spacing ribs cooperating with the transverse strut and is designed to have with respect to the channelshaped rear stiffener with an area ratio resulting in the same moment of inertia as the channel member.

This results in an. additional saving of material and weight.

In accordance with the preferred embodiment, rear stiffeners consisting of a channel member are provided on respective relatively movable column sections and on alternating sides of column sections succeeding from the outside inwardly, and another channel member is provided on the forward side in the central region. As a result, the side line guidance changes from column section to column section so that the lateral deflectability is decreased.

The expression "transverse hollow section" used for the transverse struts includes also open sections, such as channel members. The use of box-shaped transverse hollow sections is particularly preferred.

The invention provides a lifting frame in which the transverse struts consisting of hollow sections constitute runglike connecting members between the spaced apart forward and rear stiffeners when a column section is viewed in side elevation.

In a preferred arrangement, transverse struts consisting of hollow sections have in the horizontal direction substantially the same depth as the I-section members used as forward stiffeners. This results in a favorable dimensioning for a flat column in which a single-line lateral guidance between adjacent column sections is provided by a lateral guiding roller in the central channel section and a lateral guiding roller in a channel member which constitutes a rear stiffener and is provided laterally of the column section. An arrangement in which the transverse struts for all column sections consist of hollow closed box sections having the same cross-sectional dimensions.

To provide a flat lifting frame, a carrying section for a load-carrying roller is secured to each I-section member of a column section on that side of the flange that is remote from the transverse strut and said load-carrying roller extends into an outwardly directed opening of an I-section side strut associated with an inner column section.

The invention will now be explained with reference to embodiments shown by way of example on the accompanying drawings, in which Figure 1 is a diagrammatic side elevation showing a lifting truck provided with a lifting frame, Figure 2 is a transverse sectional view taken on line Il-Il and showing the lifting frame of Figure 1 adjacent to the stationary column section; Figure 3 is a diagrammatic top plan view showing the lifting frame comprising three column sections, namely, a stationary column section, two extensible inner column sections, and a load carrier shown only in part.

The guiding rollers are shown in different elevations.

In all Figures, like parts are designated with like reference characters.

Figure 1 shows a lifting truck 1 which constitutes a rack-feeding truck and comprises a driver's seat 2 and a lifting frame 3. That lifting frame consists of three column sections 4 to 6, comprising a stationary column section 4 and extensible column sections 5 and 6. A load carriage 7 provided with a load carrier 8 is vertically movably guided particularly on column section 6, which is extensible to the largest height.

A particularly hydraulically operable cylinderpiston device 9 is provided for extending the lifting frame 3 and has a piston rod which engages an abutment 9' at the top end of column section 5.

Chains 75, 76 trained in known manner around sprockets 71, 72 are connected between parts which are vertically movable relative to each other. The ends of each of said chains are respectively connected to the lower end of an adjacent inner column section and to the lower end of an adjacent outer column section. One end of the chain 75 is connected to the load carriage 7.

The column sections are guided on each other in known manner by guiding rollers. Forward guiding rollers are diagrammatically indicated in Figure 1 and serve to take up a torque which is exerted by the load carrier 8 on the lifting frame in a counterclockwise direction in Figure 1.

With respect to column sections guiding each other, one forward guiding roller 77 or 79 is provided at the top end of an outer column section and one forward guiding roller 78 or 80 at the lower end of an inner column section. Specifically, the rollers 77 and 79 are provided in column sections 5 and 4, respectively, and the rollers 78 and 80 on column sections 6 and 5, respectively.

The manner in which these forward supporting rollers are supported will be described with reference to the following Figures of the drawings.

The column sections are provided with transverse struts, which consist of transverse hollow sections and are designated 1 9 to 23 for the stationary column section and the column section 4.

Figure 2 is a transverse sectional view showing a stationary column section. All column sections are substantially alike in cross-section, apart from modifications as regards specific sectional shapes.

In accordance with the section line shown in Figure 1, the transverse strut 22 is apparent in Figure 2 and consists of a box-shaped transverse hollow section. In Figure 3, the transverse strut 23 for the stationary column section, an uppermost transverse strut 25 for the column section 5 and an uppermost transverse strut 26 for the column section 6 are apparent. The transverse struts for each inner column section are shorter than the transverse struts for an adjacent outer column section.

Side struts 27, 28 for the stationary column section, side struts 29, 30 for the column section 5, and side struts 31, 32 for the innermost column section 6 constitute forward stiffeners and are provided at the ends of the transverse struts directly on the forward side thereof.

Verticai section members 33, 34 (or 35, 36 in Figure 3) for the stationary column section, vertical section members 37, 38 for the column section 5, and vertical section members 39, 40 for the innermost column section 6 are associated with these side struts and provided at the ends of the transverse struts on the rear side thereof. In accordance with Figure 2, these section members may consist of rearwardly open channel members.

This will be particularly recommendable if a rear stiffener is used to directly guide a lateral guiding roller. A single-line lateral guidance is preferably provided. For this purpose each column section is provided on its forward side at the centre with a vertical, forwardly open channel member.

Specifically, a channel member 41 is provided for the stationary column section 4, a channel member 42 for the column section 5 and a channel member 43 for the inner column section 6. In that design, one lateral guiding roller is arranged in the central region and a lateral guiding roller mounted on an inner column section enters the central channel member of the next outer column section. Specifically, the lateral guiding roller 44 at the lower end of the column section 5 engages the channel member 41 of the stationary column section 4; the lateral guiding roller 45 at the lower end of the column section 6 enters the channel member 42 of the column section 5; and a pair of lateral guiding rollers arranged centrally on the load carriage and disposed one under the other enter the channel member 43 of the column section 6. The upper roller 46 of said pair is shown.

This design has been adopted because the load carriage 7 always remains completely in the overlap region with the column section 6.

If the lateral guiding rollers are centrally disposed on the column sections in the manner described, each of the extensible column sections will be provided with only one laterally disposed section member 38, 39, which constitutes a rear stiffener and consists of a rearwardly open channel member for receiving a lateral guiding roller 47 or 48. The lateral guiding roller 47 is provided at the top end of the stationary column section and the lateral guiding roller 48 is provided at the top end of the extensible column section 5, which is disposed adjacent to the stationary column section 4. Each of the central lateral guiding rollers 44 and'45 is provided at the lower end of the column section 5 or 6 in which the roller is mounted.That design results in a single-line lateral guidance by means of pairs of rollers offset in the transverse direction of the lifting frame.

The section members 37 and 40 which are associated with the channel members 38, 39 used as rear stiffeners consist of bars and are provided with spacing ribs 49, 50 secured to associated transverse struts. The vertically extending barshaped portion 51, 52 is so dimensioned that in conjunction with the spacing ribs 49, 50 it has the same moment in inertia as the channel members 38,39.

This design permits a saving of weight and ensures an excellent strength.

It is apparent from Figure 3 that the stationary column section 4 is provided with bar-shaped rear stiffeners 35, 36, which comprise spacing ribs, as there is no lateral guiding roller in that region.

It is stated in this connection that the transverse struts of the stationary column section 4 may consist of solid sections so that the stationary column section will be flatter than the other column sections. This is possible because the stationary column section is not raised.

It is apparent that the I-section side struts 27 to 32 are provided between their flanges with track surfaces for forward guiding rollers 53, 54, 55, 56, 57,58,59,60,61,62. Each of the inner forward guiding rollers 53, 54, 57, 58 entering a side strut 27 or 32 is disposed at the. lower end of an extensible column section, which at its top end is provided at the side struts with bearing brackets 63, 64 or 65, 66 for the upper forward guiding rollers 55, 56, 59, 60. In this connection, reference is made to Figure 1, in which the forward guiding rollers 80 and 79 correspond to the forward guiding rollers 53 and 56, respectively, in Figure 3.

In a simple arrangement, the load carriage 7 is provided with pairs of forward guiding rollers 61, 62 disposed one under the other, Only the upper roller of each pair is shown.

Because the rear stiffeners 37 to 51 consist of section members, they may be flat and the central channel members 41 to 43 may be correspondingly flat. For this reason the column sections may be closely spaced apart and at least the extensible column sections may have the same depth.

Figure 1 indicates that the transverse struts, such as the elements 1 9 to 23 for the stationary column section 4, which consist particularly of hollow box sections, are arranged like rungs between section members used as forward and rear stiffeners when viewed in side elevation.

These forward and rear stiffeners have been described and identified with reference to Figures 2 and 3.

It is apparent from Figure 3 that the load carriage 7 comprises a rear transverse wall 67, in which the lateral guiding rollers 46 are mounted, and side walls 68,69, on which the forward guiding rollers 61, 62 or pairs of forward guiding rollers are mounted, The actual load carrier 8 is suspended within the side walls, e.g., from a forward transverse wall.

The guiding rollers are undersize with respect to the associated guiding section member.

Claims

1. A lifting frame for a lifting truck comprising a load carrier which is movable along the lifting frame, a stationary column section, at least one extensible column section, and a load carriage movable along said extensible column section and adapted to carry the load carrier, wherein said column sections have profiled side struts consisting of I-sections formed with profiled openings for forward guiding rollers and lateral guiding rollers, the side struts are connected by a plurality of transverse struts, lateral rear stiffeners are provided on the rear side of the column and spaced behind the transverse struts, and channel members for receiving the lateral guiding rollers are provided in the central portion behind the transverse struts, characterized in that at least those transverse struts which are associated with the extensible column sections consist of transverse hollow sections, the transverse struts extend as far as to the outside of the respective column section, the side struts consist of Isections and are provided directly on the forward face of the transverse struts as forward stiffeners, and the rear stiffeners on at least one side are directly provided on the rear side of the transverse struts and consist of section members for guiding lateral guiding rollers.

2. A lifting frame according to claim 1, characterized in that the distance between the forward and rear stiffeners, which are directly secured to the transverse struts, is determined by the ends of the transverse struts, which consist of hollow box sections.

3. A lifting frame according to claim 1 or 2, characterized in that one rear stiffener at least on one side consists of a rearwardly open channel member.

4. A lifting frame according to claim 3, characterized in that a rear stiffener disposed on the side opposite to the channel member is barshaped and comprises spacing ribs cooperating with the transverse strut and is designed to have with respect to the channel-shaped rear stiffener an area ratio resulting in the same moment of inertia as the channel member.

5. A lifting frame according to claim 3 or 4, characterized in that rear stiffeners consisting of a channel member are provided on respective relatively movable column sections and on alternating sides of column sections succeeding from the outside inwardly, and another channel member is provided on the forward side in the central region.

6. A lifting frame according to any of claims 1 to 5, characterized in that the transverse struts consisting of hollow sections constitute runglike connecting members between the spaced apart forward and rear stiffeners when a column section is viewed in side elevation.

7. A lifting frame according to any of claims 1 to 6, characterized in that transverse struts consisting of hollow sections have in the horizontal direction substantially the same depth as the I-section members used as forward stiffeners.

8. A lifting frame according to any of claims 1 to 7, characterized in that a single-line lateral guidance between adjacent column sections is provided by a lateral guiding roller in the central channel section and a lateral guiding roller in a channel member which constitutes a rear stiffener and is provided laterally of the column section.

9. A lifting frame according to any of claims 1 to 7, characterized in that the transverse struts for all column sections consist of hollow closed box sections having the same cross-sectional dimensions.

1 0. A lifting frame according to any of claims 1 to 8, characterized in that the transverse struts of the stationary column section consist of solid sections.

11. A lifting frame according to any of claims 1 to 10, characterized in that the side struts consist of I-section members, a bearing bracket for an upper forward guiding roller is laterally provided on that flange of each side strut which is remote from a transverse strut, and said forward guiding roller enters an outwardly directed opening of a side strut which consists of an I-section member and is associated with an inner column section.

12. A lifting frame substantially as herein described with reference to the accompanying drawings.