EP0029384B1 - Lift truck with synchronised adjustement of variable rolling and gripping surfaces - Google Patents

Description

The invention relates to a forklift truck, the rolling surface and the gripping surface of which can be varied synchronously.

Currently, most industries (food, textiles, metallurgical, etc.) use, for handling parts resulting from manufacturing, bins which considerably facilitate the transport and storage of these parts as well as the supply of personal work places.

These bins have very diverse formats and, for high capacity and large tonnage bins, they are made to be handled using motorized forklifts. By cons in small handling, which covers loads varying between 30 kg and 500 kg, there are only trolleys suitable for a single tray format which requires having at its disposal several trolleys of different formats. In addition, these trolleys are made only to remove the tray from the ground in order to move it and they do not have the option of lifting them to stack them, put them in shelving or place them at a suitable height for the supply of workstations. job. For their rigidity these boxes are made with external reliefs located on the upper edge and also include passages for their grip with the hands in order to handle and stack them, which obliges the user to physical efforts in poor conditions .

By the document FR-A-1 474 111 it is common to make a forklift with variable rolling surface, composed of a chassis comprising two independent elements, identical and of adjustable spacing. The chassis of such a carriage is composed of vertical masts which are indirectly integral with horizontal beams fitted with rolling means and integral with two parallel crosspieces arranged at different heights, and supports for lifting arms mounted to slide along the masts. The corresponding crosspieces of each of the two chassis elements are designed to slide relative to each other using a rack and pinion mechanism to allow the width of the carriage to be adjusted. Such a carriage, by adapting its rolling surface, makes it possible to adapt the stability of the carriage to the load which it supports, but the fixed spacing of its lifting arms does not allow the entry of loads of different formats.

The subject of the invention is a carriage of particularly simple design and practical use, allowing a single person to easily and effortlessly grasp relatively heavy bins and of different formats, and then to be able not only to move them but also lift them within the elevation limits provided in the cart. It has already been proposed, by document FR-A-1 174 976, to produce a carriage for which the rolling surface and the elevation surface can be modified simultaneously by adjusting the spacing of two lateral frames, but this known carriage has a complicated structure and is not easy to use.

Compared to FR-A-1 474111 which already describes a carriage composed of a chassis which comprises two identical independent elements and of adjustable spacing, each chassis element consisting of a vertical mast along which a lifting arm moves , by a horizontal spar integral with the mast and provided with rolling means and by two parallel cross members integral with the mast and arranged at different heights, rack and pinion means being associated with said cross members to allow synchronized transverse sliding of the two groups of sleepers with respect to each other, the invention is characterized in that each vertical mast is directly integral with the corresponding side member, the lifting arms each comprising a set of sleepers arranged at different heights and corresponding to one lifting arms to each other, the crosspieces equipping the masts and those equipping the lifting arms being telescopic, and each telescopic crosspiece connecting th between them the masts comprising a rack and a pinion which meshes with the latter, while an endless chain connects the said pinions to allow control of a synchronized sliding of all the telescopic crosspieces allowing the spacing to be varied simultaneously between the running rails and between the lifting arms, so as to adapt the carriage to the particular format of the load to be grabbed.

To ensure good rigidity of the crosspieces when the carriage is in a position of fairly large spacing, a triple telescopic crossbar system is provided in which, inside the movable internal crossbar, an additional crossbar is disposed in free sliding. This additional cross member, which, thanks to the action of a spring system, is automatically placed in the middle of the assembly formed by the external cross member and the internal cross member in cooperation, ensuring perfect rigidity of this set.

To obtain an excellent grip on any object, the invention provides to provide the lifting arms with movable sliding parts in the form of vertical sheets with lower ends having an angled fold inwardly for grasping objects flush with the ground. with very small grip surfaces.

According to another characteristic of the invention, the elevation of the fork support of the carriage can be obtained by a central hydraulic cylinder, the movable rod of which acts by means of a pulley on a synthetic strap, one end of which is connected to a sliding cross member of the fork support and the other end is connected to the chassis of the carriage. As this cross member has the necessary games to allow easy sliding of the tubes one inside the other, it is understood that it would be liable to undergo bending under the effect of the load applied to the forks which, when the cross member is fully deployed , would cause a deformation of the parallelism of the slides of the fork support. To avoid this drawback, the ends of this crossmember are hingedly mounted on the fork support, while the other connecting crossmember of the fork supports, which is integral with these supports, ensures the rigid assembly of these supports with a squaring perfect.

The hydraulic elevation system can be variable speed and for this purpose, according to another characteristic of the invention, the piston of the actuator control pump is connected to a pedal-shaped actuating lever designed so that the user can vary the distance between the pivot axis of the actuating lever and the hinge axis of the piston to this lever thus allowing, depending on the conditions of use of the carriage, to obtain for example an elevation fast when empty or at low load and a slow rise but with minimal effort when the truck is at its maximum load.

According to yet another characteristic of the invention, the hydraulic lifting device can comprise two lateral jacks, the movable rod of each cooperating by means of a pinion with a chain fixed on the one hand to a cross member of the fork support and secondly to the chassis of the carriage. To avoid an uneven distribution of the load on the two forks, when the carriage is wide open, does not cause a pressure difference between the two cylinders detrimental to a good sliding of the support, the invention provides for synchronizing the action of the two jacks by joining the pinions together by means of a telescopic gimbal.

• la figure 1 est une vue en élévation de l'arrière d'un chariot selon une première forme d'exécution de l'invention;
• la figure 2 est une vue en plan du chariot de la figure 1;
• la figure est, à plus grande échelle, une vue en coupe longitudinale d'une liaison à trois traverses coulissantes;
• la figure 4 est une vue de face d'un chariot extensible à système élévateur hydraulique selon une seconde forme d'exécution de l'invention;
• la figure 5 est une vue partielle, de côté, du chariot de la figure 4;
• la figure 6 est une vue en plan montrant la commande mécanique du système d'élévation hydraulique;
• la figure 7 est une vue de côté d'une variante de la commande mécanique d'élévation hydraulique; et
• les figures 8 et 9 sont des vues, respectivement de côté et d'arrière, d'un chariot avec système d'élévation hydraulique à deux vérins selon une troisième forme d'exécution de l'invention.

To better understand the invention, several preferred embodiments will be described below with reference to the attached schematic drawing in which:

• Figure 1 is an elevational view of the rear of a carriage according to a first embodiment of the invention;
• Figure 2 is a plan view of the carriage of Figure 1;
• the figure is, on a larger scale, a view in longitudinal section of a connection with three sliding crosspieces;
• Figure 4 is a front view of an extendable carriage with hydraulic lifting system according to a second embodiment of the invention;
• Figure 5 is a partial side view of the carriage of Figure 4;
• Figure 6 is a plan view showing the mechanical control of the hydraulic lifting system;
• Figure 7 is a side view of a variant of the mechanical control of hydraulic elevation; and
• Figures 8 and 9 are views, respectively from the side and from the rear, of a carriage with hydraulic lifting system with two jacks according to a third embodiment of the invention.

The variable surface forklift shown in Figures 1 and 2 is composed of two elements (right and left) each comprising a mast 1, 1 ', welded vertically on a beam 2, 2' which has at its end a yoke 3 receiving in free rotation of a wheel 4 (see figure 2). On the mast 1 are fixed at different levels, by their ends, parallel crosspieces 5, 7 for example with a square section. On the mast 1 'are fixed, at corresponding heights, parallel crosspieces 6, 8 inside which are intended to slide the crosspieces 5, 7. On each lower crosspiece 5, 6 is fixed a support 9 on which is mounted a swivel wheel 10.

The elongation and retraction movement of the two elements constituting the carriage is obtained by the simultaneous sliding of the crosspieces 5, 6 on the one hand and of the crosspieces 7, 8 on the other hand. This movement, which must be carried out freely and without effort with perfect parallelism of the two carriage elements is obtained by fixing by means of screws 13, on the end of each of the internal crosspieces 5, 7, of a rack 11 designed to be able to slide against the underside of the corresponding external cross-member 6, 8.

As can be seen in the detailed view of FIG. 3, the animation of each rack 11 is obtained by means of a pinion 14 which is intended to mesh with the rack 11 and which is mounted in free rotation on a bearing 15 in the form of a yoke integral with the corresponding external cross member 6, 8. The synchronization of the movements of the two movable internal cross members 5, 7 with respect to the fixed external cross members 6, 8 is obtained by an endless chain 18 which circulates around two pinions d gear 17 mounted on the same axis 16 as the pinions 14. A crank 19, integral with the axis 16 of the upper gear pinion 14, thus makes it possible to control the variation of the width of the carriage to adapt it to the load to handle.

Advantageously, provision is made for a structure of sliding crosspieces ensuring perfect rigidity of these crosspieces, even when the carriage is in a position of great spacing for gripping objects of large width. To this end, a system with three telescopic crosspieces is produced as shown in FIG. 3 and in which an additional crosspiece 20 is mounted to slide in the internal crosspiece 7. To compensate for the difference in section with the external crosspiece 8 on which it becomes bent, the additional cross member 20 presents at a end with an external relief 20 '. For this system to be effective, it is necessary that, whatever the amplitude of the movement of exit from the internal cross member 7, the additional cross member 20 comes to be placed in the middle of the assembly formed by the external cross members 8 and internal 7, and it therefore does not have to get stuck in the outer cross member 8 or remain fitted in the inner cross member 7. For this purpose, an automatic adjustment device for positioning the additional cross member 20 is provided, this device having object, when leaving the inner cross member 7, automatically drive with it the additional cross 20, then release the latter while the inner cross 7 continues its movement.

The adjustment device comprises two springs 21, 22 each fixed at one end, respectively on the internal and external walls of the additional cross member 20. The spring 21, located on the side of the internal cross member 7, is in elastic support, through a notch 23 of the cross member 20, on the wall of the inner cross member 7 and is intended to engage, when exiting the cross member 7, in a notch 24 thereof thereby securing the cross members 7 and 20 and thus ensuring the automatic exit of the latter. The spring 22 is in elastic support, through a notch 25 of the additional cross member 20, on the inner cross member 7 and it will engage in a notch 26 formed at the end of the cross member 7 to come, after a certain stroke cross members 7 and 20 secured to one another, in a notch 27 in the outer cross member 8 which immobilizes the additional cross member 20.

A sliding support is provided for receiving, in a fixed or removable manner, forks 28 for gripping and lifting objects to be grasped. This support consists of two identical slides 29 designed to slide freely on the masts 1, 1 'and which, in the embodiment of Figures 1 and 2, are made of T-section tube. The slides 29 are connected between them, in extendable assembly, by upper sliding cross members 30, 31 and lower 32, 33 of an identical operation to the cross members 5, 6, 7, 8.

In Figures 4 and 5, there is shown a variant of the forklift according to the invention with hydraulic lifting device. To the fixed upper cross member 31 is fixed, by means of a yoke 34 integral with this cross member, one end of a strap 35 made of synthetic material passing over a pulley 36 which is mounted in free rotation in a yoke 37 integral with the free end of a piston rod 38 moving inside the cylinder body 39. The opposite end of the strap 35 is fixed to a yoke 40 secured to the fixed cross member 8. The ends of the sliding lower cross member 32 , 33 are fixed by welding to the corresponding slide 29, while the ends of the sliding upper cross member 20, 31 are articulated by a yoke 41 and an axis 42 to the slides 29. With this articulated assembly, although the traction of the strap 35 has the effect of causing a slight bending of the crosspiece 30, 31, this bending movement does not affect the slides 29 which remain perfectly parallel to each other and are therefore not hampered in their sliding along the masts 1, 1 '.

The gripping forks 28 are produced in the form of squares with arms of unequal lengths and are designed to be fixed in a removable manner on profiled parts 43 independent of each other and fixed by welding on the slides 29. represented in FIG. 4, in solid line and in dotted line, two possible positions of each fork 28. The shortest arm of each fork 28 is designed to be fixed by hooking on the corresponding section 43 by means of the appropriate form of its upper end 44. The angle of the fork 28 has at its base a longitudinal projection 45 ensuring the locking of the fork by its engagement under the cross-member 33. The forks 28 are produced in square or rectangular profile, so as to be able to adapting interchangeable removable elements constituted for example by a tube 46 which engages by sliding on the fork 28 and to which is assembled a vertical plate 47 positioned inside the carriage c omportant at its base, located at ground level, a square bend 48 oriented so that the folds 48 of the sheets 47 carried by the two forks 28 face each other. It is understood that, thanks to the possibility of extension of the carriage and by means of the square folding 48 of the sheets 47, it is possible to grasp on the ground, without requiring prior lifting, all kinds of objects such as handling bins, household appliances , furniture, even leaving only a very small free space compared to the ground.

The hydraulic lifting system of the fork supports 29 will now be described, which comprises a manual reciprocating pump controlling the hydraulic cylinder 39. The pump piston (not shown) is immersed in the reservoir 49 of the hydraulic fluid and its rod 50 is connected by a pin 51 to the end of two connecting rods 52 whose opposite ends 53 in the form of yokes are articulated by pins 54 on each side of a double lever 55. A coil spring (not shown) is mounted at inside the tank 49, so that it can slide along the rod 50, stops being provided to limit the stroke of the piston at its high point inside the tank, so as to allow its immediate driving action.

At the end of the double lever 55 is articulated about a longitudinal axis 56, an actuating lever 57 having at its end a convexly shaped surface 58 which constitutes a pedal operable by the foot of the user. The actuating lever 57, in the position of use, comes to bear by a stop 59 on the base 60 of the edges of the double lever 55, as can be seen in FIG. 6, while this lever 57 can be retracted into the vertical position (dotted position in Figure 5) and be held in this retracted position by a spring (not shown). The double lever 55 is articulated on an axis 61 mounted in a bore provided in a part 62 fixed by welding to the tank 49. Each arm of the double lever 55 has an oblong opening 63 whose base has notches 64 (three to three in number). FIG. 5) intended to selectively receive the corresponding axis of rotation 61.

The operation of the hydraulic lifting device is immediately understood from the description above. The double lever 55 having been positioned so that the pins 61 engage in notches 64 opposite the two arms of this lever, the user brings the actuating lever 57 into its position of use where the stop 59 this lever comes to bear on the lever 55. By pressing with the foot on the pedal 58, the user pivots downwards the double lever 55 around the axes 61 and, by means of the connecting rods 52, actuates the piston to discharge the hydraulic fluid from the reservoir 49 to the jack 39 while ensuring the lifting of the rod 38 and therefore of the forks 28. The return of the actuation lever in the high position being ensured by the spring (not shown) mounted on the piston rod 50 inside the tank 49. the user can modify the speed of elevation of the supports 29 of the forks 28 by modifying the arrangement of the pins 61 inside the notches 64, that is to say by varying the distance between the axes 61 and the axes 54. The displacement of the lev ier double 58 to modify the arrangement of the cxes 61 with respect to the notches 64 is obtained simply by lifting the lever 57 and moving it longitudinally.

According to a variant of the mechanical elevation speed change system shown in FIG. 7, the double lever 55 can no longer move longitudinally relative to the articulation axis 61 and it is the articulation axis 54 of each connecting rod 52 which can be moved along the oblong slot 63 of the corresponding arm of the double lever 55, to engage in one of the notches 64 provided this time at the upper part of the slot 63. To allow control easy manual shifting and therefore synchronized movement of the connecting rods 52, these are connected together by a bar 65 in the shape of a stirrup which has a handle 66 at its central part.

To lift loads of large width and significant weight, the trolley according to the invention can be equipped with a hydraulic lifting system with two lateral jacks as shown in Figures 8 and 9. A hydraulic lifting system is then used synchronized. In this device, the rod 67 of each of the two jacks 68 carries at its end a yoke 69 designed to receive a pinion 70 mounted integral with an axis 71 and which passes right through, in free rotation, the cheeks of the yoke 69. Each pinion 70 is intended to cooperate with a lifting chain 72 attached at one end to the sliding fork support 29 comprising the lifting arms 28 and, at the opposite end, to the upper cross member of the extendable frame.

To ensure the effect of synchronization in rotation of the two pinions 70, their axes of rotation 71 are rigidly coupled by means of a telescopic gimbal 73, the latter being able to be produced in the form of two or more slides (three in the form of 'execution shown), for example in square section tube.

To avoid the exit of one or the other of the slides composing the telescopic gimbal, stops are provided housed on each internal slide and constituted by springs 74 whose shape allows engagement in an openwork 75 provided for end of each outer slide.

This device makes it possible, using hydraulics, to have a perfectly synchronized elevation of two or more jacks, whatever the load differences applied to each jack by rebalancing the pressure of the fluid in each jack.

Claims (13)

1. Fork lift truck having variable rolling and gripping surfaces with synchronised adjustment facility, consisting of a chassis which comprises two independent identical elements which can be positioned at a regulable spacing apart, each chassis element consisting of a vertical post (1, T) along which a lifting arm (28) is displaced, a longitudinal member (2, 2') rigid with the post (1, 1') and provided with rolling means (4, 10) and two parallel cross-members (5, 7 -6, 8) rigid with the post (1, 1') and disposed at different heights, rack (11) and toothed pinion (17) means being associated with the said cross-membets (5, -6, 8) to allow synchronised transverse sliding of the two groups of cross-members (5, 7-6, 8) in respect of each other, characterised in that each vertical post (1, 1') is directly rigid with the corresponding longitudinal member (2, 2'), the lifting arms (28) each comprising a set of cross-members (30, 32-31, 33) disposed at different heights and corresponding from one lifting arm to the other, the cross-members (5, 7-6, 8) equipping the posts (1, 1') and those (30, 32-31, 33) equipping the lifting arms (28) being telescopic, and each telescopic cross-member (5, 6-7, 8) connecting inter se the posts (1, 1') comprising a rack (11) and a pinion (17) which meshes with this latter, while an endless chain (18) connects inter se the said pinions (17) to make it possible to control a synchronised sliding of all the telescopic cross-members (5, 6-7, 8-30, 31-32, 33) while making it possible simultaneously to vary the spacing between the travelling longitudinal members (2, 2') and between the lifting arms (28).

2. Fork lift truck according to Claim 1, characterised in that within interior cross-members (5, 7), an additional cross-member (20) which is adapted to be freely sliding permits of additional extension of the space between the chassis elements.

3. Fork lift truck according to Claim 2, characterised in that the additional slide (20) has at one end an external relief (20') which serves to compensate for the difference in cross-section in relation to the inner wall of the outer cross-member (6, 8).

4. Fork lift truck according to Claim 2 or Claim 3, characterised in that two springs (21, 22) respectively carried at the opposite ends of the inner and outer walls of the additional cross-member (20) are intended one (21) to engage into a notch (24) in the inner cross-member (5, 7) in order automatically to ensure positioning of the additional cross-member (20) after emergence of the inner cross-member (5, 7) and the other (22) is intended to engage in a notch (27) in the fixed outer cross-member (6, 8) to limit the additional extension due to the successive emergence of the additional cross-member (20) and making it possible to position this latter in the centre of the deployed telescopic assembly of the three cross-members.

5. Fork lift truck according to any one of the foregoing Claims, characterised in that the lifting arms (28) receive interchangeable gripping elements in the form of sheets (47) positioned inside the fork lift truck and the bases of which, situated at ground level, exhibit oppositely disposed squared-off folds (48), which face one another.

6. Fork lift truck according to any one of the preceding Claims, characterised in that it comprises a hydraulic lifting device in which at least one movable jack rod (38) carries a means of rotation (36) on which circulates a connecting member (35), of which one end is rigid with the chassis of the fork lift truck while the other end is fixed to a sliding cross-member (31) for the supports (29) of the lifting arms (28).

7. Fork lift truck according to Claim 6, characterised in that a said means of rotation (36) is a pulley, while the connecting means (35) is a strap made from synthetic material.

8. Fork lift truck according to Claim 6, characterised in that the ends of the upper sliding cross-member (30, 31) of the support (9), to which is attached the end of the said strap (25) are articulated on supports (29) which slide along the posts (1,1').

9. Fork lift truck according to any one of Claims 6 to 8, characterised in that the lifting jack (39) is fed by a pump (49) of which the piston rod (50) is connected by connecting rods (52) articulated on a double lever (55) pivoting in relation to the pump body (49) about an axis (61) and articulatingly connected at (56) to an operating pedal (57) which is capable of assuming a concealed vertical position.

10. Fork lift truck according to Claim 9, characterised in that the said double lever (55) has on each of its two arms an oblong slot (63) provided with spaced-apart notches (64) which make it possible to regulate the distance between the axis of articulation (61) of the double lever and the axis of articulation (64) of each connecting rod (52) on the double lever (55) in order to vary the lifting speed.

11. Fork lift truck according to Claim 10, characterised in that the double lever (55) is adapted for movement in relation to its axis of articulation (61), the latter being adapted selectively to engage in one of the notches (64) of the oblong slot (63).

12. Fork lift truck according to Claim 10, charakterised in that the axis of articulation (54) of the connecting rod (55) is movable along the oblong slot (63) to engage selectively in one of the notches (64).

13. Fork lift truck according to Claim 6, characterised in that it comprises two hydraulic lateral lifting jacks (68), each comprising at the end of its piston rod (67) a pinion (70) about which a lifting chain (72) can pass, the said pinions (70) being rotationally rigid by virtue of a telescopic universal joint (73) which ensures synchronisation of the two piston rod outputs.

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