GB2053153A

GB2053153A - Lift truck

Info

Publication number: GB2053153A
Application number: GB8021566A
Authority: GB
Original assignee: Jungheinrich Unternehmensverwaltung KG
Current assignee: Jungheinrich AG
Priority date: 1979-07-02
Filing date: 1980-07-01
Publication date: 1981-02-04
Also published as: SE8004479L; DE2926657A1; FR2460883B1; FR2460883A1; DE2926657C2; GB2053153B; IT8023157A0; IT1132147B

Abstract

A lift truck (1) has a lifting mast (6) having fixed and traveling portions and a lifting cylinder arrangement (11) is located either in front of or behind a frame strut which establishes a blind spot (7) as far as the driver of the vehicle is concerned when located in the control position (5). A load chain is connected to a central point on the load carrier (14) and a chain guide roller arrangement is angularly disposed with respect to the lateral extent of the mast. The invention is applicable to simple non-telescoping masts (Figures 2 and 3) or to single or multiple telescopic masts (Figures 4 to 9). <IMAGE>

Description

SPECIFICATION Lift truck The invention relates to lifttrucks.

It is known, with respect to lift trucks having a conventionally constructed simply telescoping lifting masts with a lifting cylinder arranged centrally or substantially centrally between the carrying profiles of the carrying frame to improve the visibility in such a way that instead of this one cylinder for dead lift and main lift, at least two lift cylinders are arranged in the region of the lateral mast frame parts, load chains guided independently and reversed being arranged for each cylinder arrangement. The larger construction costs associated therewith as well as the lower degree of overall effectiveness makes this disadvantageous.

Often, with still greater disadvantage, because from the sectional point of view it again hinders visibility, it is necessary in a multiple telescopic lifting mast, additionally to place centrally with respect to the lateral multiple cylinder arrangement a still further cylinderforthe achievement of a large dimension of dead lift which must include as a general rule a hydraulic connection which influences the operational security as it is arranged for vertical movement since it is connected to the parts arranged for vertical movement.

An object lying at the basis of the present invention is to create a lift truck having a lifting mast which guides either only a load carrier or, on the other hand, at least one travelling mast and is constructed as a frame type, which is also true of the travelling mast and, having simple chain arrangement, which as a result of the rational construction in combination with the vehicle construction makes possible a broadly dimensioned sight window through the frame type lifting mast, which is also attainable with a telescopic lifting mast in such a way that a lifting cylinder arrangement constructed also with essentially smaller dimensions does not lead to a restriction of the field of visibility and vertical movement of hydraulic cylinder connections are avoided.

In accordance with the invention, there is provided a lift truck having a lifting cylinder arrangement arranged to one side with respect to the central longitudinal axis of the lift truck on a frame type lifting mast, at least one load chain connecting the lifting cylinder arrangement to a central point of a load carrier and a control position arranged asymmetrically behind the lifting mast, and wherein the lifting cylinder arrangement is arranged in a given blind spot immediately in front of or behind a frame strut of the fixed portion of the lifting mast, and wherein a load chain guide roller arrangement is disposed angularly to the transverse extent of the lifting mast.

The lateral, and therewith asymmetric, arrangement of a piston and cylinder arrangement presents initially a surprising solution since with the asymmetrical arrangement of the control position the blind spot behind the two lateral frame structure groups of the lifting mast, also on a telescopic lifting mast, is rather large so that the invention makes use of such a dead spot. As a result, the asymmetric, i.e.

laterally displaced arrangement, of the control position with respect to the travel direction of the lift truck, corresponding to the lateral arrangement of the steering wheel in a vehicle is practical, whereby however in combination with such a vehicle construction in a surprising manner the visibility of a frame type lifting mastthrough the centre region is substantially improved and it is also possible to use relatively large lifting cylinder arrangements (with respect to diameter) in such a way that they do not appear in the field of view of the driver.

Such a lifting mast arrangement already presents a surprising solution which, even with a one-sided application of the lifting forces, can create a laterally parallel constant lifting movement. Thus, the cooperating guide parts can be constructed corres pondingly.

With the arrangement at least of one lateral lifting cylinder arrangement in a given dead spot the location of the lifting cylinder arrangement is out of the plane of the lifting mast. Preferably, the chain guide roller arrangement provides guidance for the load chain between essentially the centre line of the load carrier and of the at least one lifting cylinder arrangement. As a result it is possible to obtain a suitable load connection on the load carrier in a lateral arrangement of the lifting cylinder arrangement. In a particularly preferred embodiment of the invention this roller arrangement is mounted on the upper or lower part of a fixed mast or on a travelling mast in the form of a carrier arranged at an angle to the transverse plane of the lifting mast.With reference to the roller arrangement preferably at least two chain guide rollers are arranged on a common carrier which is constructed to extend at an angle to the transverse extension of the lifting mast.

In this connection a preferred embodiment lies in that two load chain guide rollers on the carrier are mounted at different heights along the vertical axis of the lifting mast and a return roller is correspond inglyarranged on a head of a movable piston of the lifting cylinder arrangement.

In a further preferred embodiment the load chain has one end anchored to the fixed portion of the mast and is guided to the load carrier over the return roller by way of two chain guide rollers arranged at different heights and an abutment for the piston head is arranged on the travelling mast. As a result it is possible to operate a telescopic lifting mast in such a way that the load carrier is lifted through a predetermined distance until the piston head contacts its abutment on the travelling mast whereupon the travelling mast and the load carrier are moved in the same sense, nevertheless with different velocities, in such a way that the load carrier reaches its upper position on the travelling mast when this has been withdrawn so far that the piston head has lifted the abutment on the travelling mast into its uppermost position.The chain guide rollers arranged in different vertical positions means that, on further operation of the piston and cylinder arrangement or further lifting of the movable piston head a lifting of the abutment and a further movement of the load carrier to a greater height occurs. Thus, the invention provides a construction which after exhaustion of the dead lift the travelling mast is directly moved by way of the cylinder while the load carrier moves further up to its upper end position.

To provide a particular advantage the load carrier is movable in a limited dead lift through the approach of the piston head to the abutment and, after withdrawal of the travelling- mast by the spacing of its abutment from the piston head is movable through a further lift when the two chain guide rollers are arranged in the upper section of the travelling mast.

The lifting cylinder is extensively protected in installation in the apparatus-with respect to external impact effects if, preferably, the abutment is pro vided on a rearwardly extending transverse carrier of the moving mast and the lifting cylinder is arranged within the lateral external- periphery of the travelling mast frame underneath this transverse carrier.

With respect to the described embodiment it is seen that in addition to the obtaining of a good visibility through the mast, the constructional cost is kept low. Furthermore, the hydraulic efficiency and the small construction weight are economic, the latter in particular being important for lift trucks.

constructed in accordance with the counterweight principle since the part of the weight lying outside of the wheel base of the load handling device must be compensated behind the front wheels by means af a counterweight having regard to a longitudinal stability factor.

Also with reference to the simple lifting cylinder arrangement and load chain guidance it leads to the weight saving that the second and third chain guide rollers are arranged in the upper section of the travelling mast laterally in the neighbourhood of the lifting cylinder by way of carrying plates on the upper transverse carrier of the travelling mast frame, seen from the lifting cylinder centre point, in inclined location with reference to the chain abutment of the load carrier.

A constructional advantage is also maintained in the multiple telescopic mast embodiment when, in the case of the aforementioned basic arrangement, it has one lifting cylinder effective only for the main lift and additionally a dead lift cylinder is provided in a mirror image position to this cylinder on the other carrying frame side.

A particularly advantageous solution of this kind lies in that the lifting cylinder arrangement effecting the main lift cooperates with or is connected with an abutment on the neighbouring travelling mast and a dead lift cylinder arrangement is arranged in a mirrar image position on the other fixed mast side and the chain guide roller arrangement on the travelling mast is arranged therefor.

Preferably, the lift load requirements of the main lift cylinder arrangement, which is longer than the head lift cylinder arrangement, is reduced in such a way that this lifts the first travelling mast directly.

As inthe case of the simply telescoping lifting mast, in the case of the multiply telescoping mast, a very simple load chain guidance is obtained if, for the head lift, the load chain anchored at one end extends over a first chain roller supported on a cylinder head and movable by means of the dead lift cylinder and over a second chain roller avoiding the cylinder angle pull and supported on a travelling mast part of the first travelling mast, further over a third chain roller equally supported on the aforementioned travelling mast part as well as over a fourth chain roller supported on a travelling mast part ofthe second travelling mast centrally or approximately centrally of a load carrier arranged to be movable upwardly on the second travelling mast and lifting this up into its uppermost end position.

An advantageous embodiment of the invention is obtained when the dead lift cylinder arrangement is suspended and the chain guide roller arrangement is arranged in the upper zone of the adjacent travelling mast so that the lifting cylinder and the dead movement cylinder arrangement are arranged symmetrically to each other in mirror image in plan view.

In this way, in an embodiment including a multiple telescopic mast having at least two travelling masts, wherein a load chain for the dead lift supported at one end an the fixed mast is. guided aver a movable chain guide roller on the dead lift cylinder arrangement and over a lower chain guide roller on the first travelling mast to an upper chain guide roller on the second guide mast, it is advantageously included that the lifting cylinder arrangement cooperates immediately with an abutment on the second travelling mast and at least one further load chain is provided from the lower end of the second travelling mast over a chain guide roller on the upper part of the firsttravel ling mast to the fixed mast, whereby the chain guide roller arrangement is provided with chain rollers at the lower end of the first travelling mast and arranged at an angle to the transverse direction of the lifting mast.

For an economic construction and for a small spare parts requirement it is particularly important that the working faces of the lift cylinders are kept to the same dimension, namely in the simple telescopic lifting mastembodimentwith small dead lift and in the multipletelescopic lifting mast embodiment.

Since, for the necessary movement requirements of the dead lift and the main lift cylinder in the present arrangement no particular measures are to be met, both lifting cylinders can be supplied by one fixed hydraulic connection lead at the same time. A fixedtubular connection is efficient although if necessary a flexible section can be introduced in order to prevent rubbing of the pipes.

The required constructional simplicity can be obtained among other things in that chain connections exist between the fixed mast and the second travelling mast which are led over chain rollers supported on the first travelling mast.

According to a preferred construction the chain guide rollers for the two load chains are provided laterally and a first load chain is guided from the side to the middle try way of the chain roller arrangement. As a result two carriers can be provided with chain guide rollers arranged at an angle to the transverse extension of the lifting mast.

In a particular advantageous manner such parts of the described lifting mast construction characteris tics are combinable with the simple telescopic lifting mast with small dead lift and with the multiple telescopic lifting mast with large dead lift which makes it possible to manufacture a simple telescopic lifting mast with large dead lift; in particularthis refers to the lifting cylinder and load chain arrangement.

The invention is hereinafter further described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective general view of a simple telescopic lifting mast for a lift truck having one lifting cylinder.

Figure 2 is a schematic representation of the mast of Figure 1 showing the completed dead lift; Figure 3 is a view as in Figure 2 but with fully completed overall lift; Figure 4 is a perspective general view of a simple telescopic lifting mast for a lift truck with greater dead lift and two lifting cylinders; Figure 5 is a schematic representation of the mast of Figure 4 showing the fully completed larger dead lift; Figure 6 is a view as in Figure 5 but with fully completed overall lift; Figure 7 is a perspective general view of a two-part telescopic mast having two lifting cylinders; Figure 8 is a schematic representation of the mast of Figure 7 showing the fully completed large dead lift; Figure 9 is a view as in Figure 8 but with fully completed overall lift; Figure 10 is a view of a lift truck with a lifting mast according to Figures 1 to 3 and seen in plan view.

The following description refers to the parts essential to the understanding of the function so that cooperating guide elements even if they are illustrated are not otherwise described as long as one is dealing with known construction details.

The described lifting mast stands as is understood from Figure 10 on a lifting vehicle 1 which has, for example, two forward wheels 2,3 and a drive and steering wheel 4 arranged at the rear. The control position 5 is arranged asymmetrically to the longitudinal central line, in accordance with Figure 10 for example set to the left of the longitudinal middle line.

The mast parts of a lifting mast illustrated as a whole by 6 are arranged symmetrically to the longitudinal middle line. With reference to the asymmetric arrangement of the control position 5 it is noticeable that the dead spot 7 related to the strut arrangement 8 of the lifting mast 6 is larger than the dead spot 9 related to the strut arrangement 10. The lifting cylinder arrangement 11 is therefore arranged in the zone of the strut arrangement 8 within the larger dead spot 7 and the location between the strut arrangement 8 and the control position 5 has the advantage that an embodiment protected against external interference is provided.

In accordance with Figures 1 to 3 the lifting mast 6 consists of the fixed mast 12 and the load carrying travelling mast 13 suitably guided thereon. Both masts consist of lateral outer frame struts so that they leave free between themselves a wide viewing window. A load carrier 14 is suitably guided on the travelling mast 13 and is fixed in its alignment on the travelling mast by guide rollers.

In correspondence with the illustration with respect to Figure 10 a lifting cylinder arrangement 11 is provided, with reference to Figure 1, behind the strut arrangement 8 of the fixed mast and of the travelling mast, the cylinder 15 of which is supported on the lower part of the fixed mast and the piston rod 16 of which is movable upwardly underneath an abutment 17 which abutment 17 is arranged to extend rearwardly (in this embodiment) of the travelling mast 13. If the lifting cylinder arrangement were provided in front of the lifting mast the abutment 17 would be correspondingly provided on the forward side.

It can be seen that support means 20 to 23 are provided on the lateral struts 18, 19 of the fixed mast in order to locate the lifting mast on the lift truck and also to orient it in a defined position with respect to the vertical. Furthermore, it can be seen that the struts interengage by way of lateral flanges and, in general, rollers (not illustrated) are provided for guidance on the opposed sides.

In the illustrated embodiment the piston rod 16 of the lifting cylinder arrangement carries a chain reversing roller 24 at its upper end on the piston head 25 which can come into engagement with the abutment 17 on the travelling mast and is located on the piston rod 16.

The abutment 17 is, according to Figure 1, united with a carrier 26 which is arranged on the travelling mast 13 and as a whole, or at least includes a section 27 which, runs at an angle to the transverse extension of the lifting mast 6. Two chain guide rollers 28, 29 are supported at different heights in this carrier and are movable upwardly therewith and with the travelling mast 13.

In this context nevertheless it is additionally pointed out that the two chain guide rollers 28, 29 are aligned in the direction of the reversing roller 24 arranged on the piston rod 16 at an angle to the transverse extension to the lifting mast, so that a load chain 31 is guided from a central fixing point provided on the load carrier 14 vertically upwardly and over the reversing roller 24 to a fixing point 23 on the fixed mast, for example for the simplification ofthe embodimenttothe upper end ofthe cylinder 34 of the lifting cylinder arrangement 11.

Thus, with reference to Figures 2 and 3, it is understood that the lifting cylinder arrangement 11, in the case of a retracted piston rod, is arranged with its piston head 25 and the reversing roller 24 initially underneath the abutment 17. Upon operation of the lifting cylinder the load carrier 14 is lifted out of the dotted line position by a distance 30, that is it is lifted through a limited dead lift without the lifting mast being moved. As a result the lifting cylinder arrangement 11 also operates as a dead lift cylinder arrangement. After the dead lift the lift path 35 is traversed by direct involvement of the travelling mast 13so that the load carrier finds itself then in the position 14". In this situation the reversing roller 24 lies approximately at the same height as the upper load chain guide roller 29. With further movement of the piston rod 16 a lifting movement 36 is obtained so that the load carrierfinishes in its uppermost position 14s in which the abutment 17 is lifted from the piston head 25 as a result of the chain guide rollers 28, 29 being arranged in different heights.

Thus, it is seen that by way of the described embodiment a particularly rational lifting arrangement is obtained whereby the spacing between the chain guide rollers 28,29 can also be larger than illustrated.

If one is speaking of load chains it is understood that other tension elements such as cabies or the like are utilisable.

Figures 4 to 6 show a further embodiment in the form of a simple telescopic lifting mast 37 having greater dead lift. This has, corresponding to the previous embodiment, a fixed mast 12 and a travelling mast 13 which has an abutment 17 for the lifting cylinder arrangement 11. In this embodiment however the piston rod 16 is connected to the abutment 17 or it remains constantly in contact with this abutment. The lifting cylinder arrangement 11 is arranged as in the previously described embodiment laterally in the region of the strut arrangement 8 of the lifting mast assembly. According to Figures 4 and 5 however a second lifting cylinder arrangement 38 is provided to hang down from the upper end of the travelling mast 13, and also in the blind spot of the strut arrangement 10, that is, the cylinder 39 is fixed to an abutment 40 at the upper end of the travelling mast 13.To this cylinder or to the abutment 40 a load chain 41 is fixed which is guided by way of a reversing roller 42 on the piston head 43 of a piston rod 44 of the lifting cylinder arrangement 38, and arranged at an angle to the transverse extension of the lifting mast 37, to a carrier 45 on which, in this case for example, two chain guide rollers 46,47 are so supported at the same height that the outward run of the load chain is guided to a central abutment 49 of the load carrier 14. The carrier 45 is thereby fixed to the withdrawable abutment 17 or 40 and is movable vertically with the withdrawable mast.

As can be seen from Figures 5 and 6 initially the lifting cylinder arrangement 38 which is also denominated as the dead lift cylinder arrangement, is operated so that the reversing roller 42 is withdrawn downwardly into the position thus shown. As a result the load chain 41 carries the load carrier 14 out of the lower into the illustrated position at the upper end of the travelling mast 13. Thereafter the lifting cylinder arrangement 11 is withdrawn into the position shown in Figure 6 so that the travelling mast 13 is also moved into the upper position. Both lifting cylinder arrangements 11 and 38 are connected with each other through a fixed connection line 48 whereby the connection can be also guided through a piston rod.With reference to the loading it is ensured by common effective cross-sections that initially the dead lift cylinder arrangement 38 is withdrawn before the lifting cylinder arrangement 11 is subject to pressure fluid. An elastic bend is preferably introduced into the fixed connection line 48 of a tubular line.

Figures 7 to 9 show a multiple telescopic lifting mast 50 having a fixed mast 12, a lifting cylinder arrangement 11 arranged thereon which cooperates with an abutment 17 on the travelling mast 13 in the manner described with reference to Figures 4 to 6. In the described embodiment a second travelling mast 51 is vertically movably guided on the first travelling mast and the load carrier 14 is in this case vertically movable thereon. The load carrying chain 52 guiding it is guided over a reversing roller 53 at the upper end of the second travelling mast 51 and over at least one reversing roller 54 at the lower end of the travelling mast 13 to a reversing roller 55 on the piston rod 56 on a dead lift cylinder arrangement 57 which in this case is arranged on the base 58 of the fixed mast 12. The load carrying chain 52 is fixed on this base for example at 59 (Figure 9) or 59' (Figure 7).The axis of the reversing roller 53 runs in the transverse direction on the mast. As a result a chain connection length is arranged in the load carrying chain in the region between the reversing roller 53 and a reversing roller 54' nearthe reversing roller 54, which length connects the vertical load chain sections to each other. The second travelling mast 51 is, as seen from Figure 7, moved by two load carrying chains 60,61 which on the one hand engage at their lower end at 62,63 on the second travelling mast 51, and pass over respective reversing rollers 64, 65 at the upper end of the side struts 66, 67 of the first travelling mast and from there to an anchoring 68,69 in the region of the base or a correspsonding part of the fixed mast.The reversing rollers 54, 54' are also arranged in this embodiment on a carrier 72 which runs at an angle to the transverse direction of the travelling mast and in any case at least in the section in which the reversing rollers 54, 54' are supported.

In this embodiment there results in accordance with Figure 8 initially a dead lift of the load carrier 14 over the second travelling mast 51, corresponding to the distance 70 and thereafter the lifting cylinder arrangement 11 becomes effective in order simultaneously to move the first travelling mast 13 and the second travelling mast 51. Both main lifting cylinder arrangement 11 and the dead lift cylinder arrangement 57 are connected with each other through a fixed parallel line 71 whereby as a result of the working faces being equal the operation is continuous.

The invention is naturally not limited to the illustrated exemplary embodiments but rather can be changed in several ways without departing from the basic concept of the invention. So, for example, instead of the single load chains guided to the respective mast centres in the mast profile zones, two load chains can be provided in other chain roller arrangements; a tendency to pull at an angle with respect to the telescopic parts can be dealt with by corresponding chain guidance; multiple telescopic lifting cylinders can be utilised and the like.

Claims

1. Alifttruckhaving a lifting cylinder arrangement arranged to one side with respect to the central longitudinal axis of the lift truck on a frame type lifting mast, at least one load chain connecting the lifting cylinder arrangement to a central point of a load carrier and a control position arranged asym metrically behind the lifting mast, and wherein the lifting cylinder arrangement is arranged in a given blind spot immediately in front of or behind a frame strut of the fixed portion of the lifting mast, and wherein a load chain guide roller arrangement is disposed angularly to the transverse extent of the lifting mast.

2. A lift truck according to claim 1, wherein the chain guide roller arrangement provides guidance for the chain between essentially the centre line of the load carrier and of the at least one lifting cylinder arrangement.

3. A lift truck according to claim 1 or claim 2, wherein at least two load chain guide rollers are arranged on a common carrier which is constructed to extend at an angle to the transverse extension of the lifting mast.

4. A lift truck according to claim 3, wherein two load chain guide rollers on the carrier are mounted at different heights along the vertical axis of the lifting mast and a return roller is correspondingly arranged on a head of a movable piston of the lifting cylinder arrangement.

5. A lift truck according to claim 4, wherein the load chain has one end anchored on the fixed portion of the mast and is guided over the said return roller and the two load chain guide rollers arranged at different heights, and wherein an abutment for the piston head is provided on a travelling mast portion.

6. A lift truck according to claim 5, wherein the load carrier is movable in a limited dead lift during approach of the piston head to the abutment and is movable through a further lift during movement of the travelling mast portion when the abutment is lifted away from the piston head, the two chain guide rollers being arranged in the upper section of the travelling mast portion.

7. A lift truck according to any one of claims 1 to 5, wherein the abutment is provided on a rearwardly extending transverse support of the travelling mast portion and the lifting cylinder arrangement is arranged within the lateral external periphery of the travelling mast portion frame underneath this transverse carrier.

8. A lift truck according to any one of claims 1 to 7, incorporating a multiple telescopic mast and wherein the lifting cylinder arrangement effects the main lift and cooperates or is connected with an abutment on the adjacent travelling mast portion and a dead lift cylinder arrangement is symmetrically arranged on the other side of the fixed mast portion and, with respect to this, the chain guide roller arrangement is arranged on the travelling mast portion.

9. A lift truck according to claim 8, wherein the lifting cylinder arrangement effecting the main lift is made longer than the dead lift cylinder arrangement.

10. A lift truck according to claim 8, wherein the dead lift cylinder arrangement depends and the chain guide roller arrangement are arranged in the upper region of the adjacent travelling mast portion, the main lift cylinder arrangement and the dead lift cylinder arrangement being arranged symmetrically with respect to each other in plan view.

11. A lift truck according to claim 8 incorporating a multiple telescopic mast having at least two travelling mast portions wherein a load carrying chain supported for the dead lift of the load carriage on one end of the fixed mast portion is guided over a movable chain guide roller on the dead lift cylinder arrangement and over a lower chain roller on a first travelling mast portion to an upper chain roller on a second travelling mast portion.

12. A lift truck according to any one of claims 8 to 11, wherein the main lift cylinder arrangement cooperates directly with an abutment on a first travelling mast portion, and at least one further load carrying chain is provided from the lower end of a second travelling mast portion over a chain guide roller arranged high on the first travelling mast portion to the fixed mast and the chain guide roller arrangement is provided with chain guide rollers arranged at an angle to the transverse direction of the lifting mast on the lower end of the first travelling mast portion.

13. A lift truck according to claim 13, wherein the chain guide rollers for the at least one further load carrying chain are arranged laterally of the lifting mast and the first load carrying chain is guided from the side to the centre by way of the chain guide roller arrangement.

14. A lift truck according to any one of claims 8 to 13, wherein the working faces of the main lifting and dead lift cylinder arrangements are equally dimensioned.

15. A lift truck according to any one of claims 7 to 14, wherein the main lift and dead lift cylinder arrangements are operated in parallel by way of a rigid hydraulic connection line and simultaneously actuated.

16. A lift truck as hereinbefore described with reference to Figures 1,2,3and 10, or Figures 4to 6, or Figures 7 to 9 of the accompanying drawings.