FR2598142A1 - FORK LIFT TRUCK WITH AN ORIENTABLE CONTROL BLOCK AND A MOBILE HEAD CARRIER ASSEMBLY. - Google Patents

Abstract

A FORK LIFT TRUCK CONSISTS OF A DIRECTIONAL CONTROL BLOCK1 AND A HEIGHT-MOBILE LOAD CARRIER11 ASSEMBLY WHICH CAN BE ADJUSTED IN HEIGHT IN RELATION TO THE CONTROL BLOCK BY MEANS OF A HYDRAULIC CYLINDER6 LOCATED IN THE CONTROL BLOCK1, AND WHICH IS GUIDED ON LEDIT CONTROL BLOCK. A LOAD CARRIER25, IN PARTICULAR IN THE FORM OF LOAD CARRIER FORKS, IS ARRANGED AT A FIXED ANGLE IN RELATION TO THE LOAD CARRIER ASSEMBLY11 AND CAN BE MOVED AT HEIGHT RELATIVE TO THE CONTROL UNIT. BELOW THE LOAD CARRIER ARE WHEELS37 MOUNTED IN PARTICULAR ON A SWIVEL LEVER36, WHOSE WHEEL SUPPORTS, IN PARTICULAR SWIVEL LEVERS36, CAN BE MOVED IN HEIGHT, AND IN PARTICULAR PIVOT WITH RESPECT TO THE HEIGHT ADJUSTMENT25 DRIVE PLAN, AS A FUNCTION OF A HEIGHT ADJUSTMENT DEVICE THAT IS ASSOCIATED WITH THE ACTUATION OF THE HYDRAULIC CYLINDER 6. FOR THE PARALLEL GUIDANCE OF THE LOAD CARRIER ASSEMBLY11 AND OF THE CONTROL UNIT1, IT IS PROVIDED FOR THE MOBILE WHEELS AT HEIGHT, IN THE CONNECTION RODS18, AN ADJUSTING DEVICE29 THAT CAN BE ACTUATED, AS ELECTED, AND ALLOWING, WITH RESPECT TO THE PARALLEL POSITION IN RELATION TO THE TRAVELING AREA, TO MODIFY AT WILL AND AT ALL LEVELS THE ANGULAR POSITION OF THE LOAD CARRIER25 IN RELATION TO THE TRAVELING PLAN. IN ONE EMBODIMENT, THE ADJUSTMENT DEVICE 29 IS COMPLIANT AS A MASTER CYLINDER. SUCH ADJUSTING DEVICE CAN ALSO BE MOUNTED ON RODS WHICH ARE USED TO MOVE THE SWIVEL LEVERS36 AND WHICH ARE ARTICULATED ON THEM.

Description

259814'2

  The invention relates to a forklift with an adjustable control block and, guided on it, a load-bearing assembly movable in height. The invention relates to a forklift with a swiveling load-carrying assembly ______________________________________________________ which can be adjusted in height with respect to the control unit by means of a hydraulic cylinder arranged in the control unit and which is guided on the control unit; below the load carrier disposed at a fixed angle relative to the load carrier assembly, in particular load-carrying forks, being provided with movable rollers in height and mounted in particular on a pivoting le10, including the wheel supports, in particular the pivoting levers, can be moved in height as a function of a vertical control system corresponding to the actuation of the hydraulic cylinder to allow adjustment of the height of the load carrier parallel to the rolling plane. 15 The mobile load-carrying assembly in height is guided from

  preferably in parallel on the control block.

  The term forklift truck also refers to a load carrier in the form of a plate which is supported at its end remote from the load carrier assembly,

  by rollers of the aforementioned type mounted as indicated.

  Fork lift trucks of this kind, also known as small lift trucks, can be maneuvered manually or also mechanically and fitted, if necessary, with a driver's seat. Often such carts are provided

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  drawbars at the end of which is a control head with operating levers for the various functional assemblies.

  In a particularly advantageous embodiment, the pivoting levers can be oriented by means of rods which extend respectively between a pivoting lever

  and a pivoting linkage element, which also applies to the connecting rods between the control unit 10 and the load-carrying assembly.

  Normally, the aforementioned vehicles operate in such a way that the forks, once engaged in a pallet or

  under a load, are lifted enough to lift the load from the ground.

  Fork lift trucks with adjusting bars of the aforementioned kind are described in DE-GM 17 69 144 and

in DE-GM 17 87 367.

  A forklift according to DE-AS 1 199 954 certainly provides a connection between the control unit and the load-carrying assembly at only three points, but it does, however, require on the head of the piston rod a ball joint for fixing the load-bearing assembly, since the other lower links only consist of pivot points in the region of a joint

connecting rods.

  On well-known vehicles of this kind, one problem consists in making the horizontal parts of the fork adjustable relative to the control unit in the sense that, on a horizontal rolling plane, the adjustment parallel to the rolling plane is practically modified and that the ends of the 35 horizontal parts of the fork are raised or lowered. This should facilitate loading and unloading. he

  there is also a forklift designed for handling loads deposited only on sheets of paper.

  Belgian patent 571,395 describes a forklift whose lifting mast can be adjusted with the load carrier with respect to previous casters on claws protruding forward because, on these claws, a pair of wheels having a ground clearance greater than that of the support rollers can be moved to lift the front ends of the claws and thereby tilt the support of the lifting system. This tilting can be further reinforced by a possibility of additional adjustment of the assembly with the claws relative to the adjustable control unit of the vehicle. In this embodiment, the actual load carrier is guided on the claws so that the adjustment is then also limited. The construction of this vehicle is very complicated. Its purpose is to allow,

  in particular under load, crossing slopes or undulations of the ground without touching the ground and respectively depositing the load correctly.

  This is also the objective of the present invention. In DE-P 1 051 196, a stacking trolley is described, the load-carrying fork of which can be adjusted in such a way that, the guide mast being integral with the chassis, its front edge is raised obliquely from the rolling plane or even that it is lowered approximately up to this, in order to reliably and above all during transport hold a lifted load. To this end, the well-known stacking trolley comprises an adjustable support for the vehicle body on its rear axle guided by pivoting levers in such a way that the entire vehicle body, with the driver's seat and the guide mast is inclined. This is complicated and the possibility of adjustment is limited although this system already makes it possible to obtain certain adjustments for

  hold pallets or other loads in such a way as to safely guide them during transport.

  This complicated vehicle construction works with

considerable inertia.

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  However, there is in particular the problem that, when handling pallets with vehicles of the aforementioned type, the approach surface for the vehicle and the storage area for the pallet are not on the same plane. For example, the pallet can be placed horizontally, while the carriage rolls on an inclined plane, for example a ramp, or vice versa. The problem then arises of being able to adjust the horizontal parts of the fork so as to compensate for the different inclinations of the deposit area or of the rolling area and to be able to engage the horizontal part of the fork or the carrier. fully and smoothly loads under or

in the palette.

  In this context, the well-known embodiment described last is not satisfactory because the construction of the vehicle does not allow sufficient inclination, apart from

  a body adjustable in height on the rear axle.

  The object of the present invention is to improve a vehicle of the aforementioned type of simple construction in such a way that the load carrier can be inclined relative to the rolling plane and that it also allows the gripping of loads when the rolling plane and the ground on which the load rests are inclined relative to each other, the system 25 for the inclination of the load carriers relative to the rolling plane must, in addition, be simplified while allowing in a way simpler both gripping and depositing

  loads and crossing uneven ground.

  According to the invention, this object is achieved by the fact that the connection linkage for the movable rollers in height comprises an adjustment device which can be actuated as desired and that the angular position of the load carrier relative to the rolling plane can be modified as desired. 35 Thanks to the adjustable adjustment of the roller supports and, consequently, of the load carrier in superposition with the parallel movement in height, it is not only possible to

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  maneuver such a forklift equipped with a hydraulic cylinder in a normal manner, that is to say to move up or down, for example, the fork carrying the load parallel to the rolling plane by actuation of the hydraulic cylinder or drawbar, but also to tilt the load carrier, for example in the form of load-carrying forks, with respect to the rolling plane by acting on the adjustment device with parallel guidance between the control unit and the door assembly -charge. It must then be taken into account that the load carrying forks are oriented mechanically at a fixed angle relative to the load carrying assembly so that, during an angular adjustment, the whole of the carriage pivots around the point of contact at least one load wheel on the control unit. Two characteristics are grouped together here in the sense that parallel guiding between the control unit and the load-carrying assembly is always ensured and that therefore the guiding members can be made in a very simple manner, but that the direction of the load-carrying fork or of a corresponding load-carrier also provided in the context of the present invention can be inclined relative to the rolling plane in the sense that the front edge of the load-carrier or the arm ends load support can be lowered or lifted above the rolling surface. The surprising fact is precisely that this result can be obtained with the construction of the vehicle in question without providing an articulation between the

  control unit and the load carrier assembly. Such an articulation has drawbacks with regard to the arrangement, on the one hand, and the load between various angular adjustments, on the other hand.

  The combination of a parallel guide of the load-carrying assembly and the control block already constitutes an advantageous solution because it also creates the necessary condition for precise adjustment of the load-carrying forks or of a similar load-bearing. The insertion of at least one adjustment device into the connecting rod allows for a determined adjustment of the lifting, that is to say also for a

  defined adjustment of the hydraulic cylinder, a modification of the inclination of the load carrier, in particular of the load-carrying forks. This is also the case in the absence of precise parallel guidance.

  In view of the above considerations, a particularly advantageous embodiment then consists in that, when the rollers mounted on a pivoting lever can be oriented by means of rods which extend respectively between a pivoting lever and a linkage element pivoting, the length of the rods shaped as connecting rods between the pivoting levers and the linkage elements can

  be changed by the adjuster.

  The result is a surprising solution which also makes it possible to easily transform existing vehicles being

  given that these vehicles are generally fitted with rods between the pivoting levers and the linkage elements.

  The adjustment for each linkage element can be carried out in different ways. According to the invention, a mechanical embodiment is also provided in the form of a tensioning nut with threads opposite at its ends.

  into which the rod sections are screwed, a jack 25 being provided for each tensioning nut.

  However, it is particularly advantageous to provide an adjustment device in the form of a cylinder-piston system.

  In a preferred embodiment of the invention, the rods 30 are then introduced respectively as rods of

  piston in a cylinder articulated on the linkage elements. The piston can then be urged at least unilaterally for the adjustment of the piston rod.

  In the latter case of unilateral solicitation, the

  return movement is effected by the load of the device.

  The ability to change the length of the rods provides

  a surprisingly simple solution to the problem posed.

  The term connecting rods also applies to a system of levers provided between the load-carrying assembly and

  the control unit and articulated with connecting elements, in particular rods, for the castor supports, in particular the pivoting levers.

  i An advantageous embodiment of the invention of the aforementioned genre is distinguished by the fact that it also includes, where appropriate, a mechanical adjustment device in the form of a cable control or a system of levers. According to what has been said previously, such an adjustment device can be used advantageously to actuate at least one cam or a bent lever, for example, inserted in the connecting rods to modify their adjustment imposed by the hydraulic cylinder. In combination with the connecting rods as a lever system, it is advantageous to provide an adjustment device in the form of at least one master cylinder pivotally mounted in the control unit and the piston rod of which is articulated with a lever on at least one connecting rod 25. This allows the realization of a simple system which can be connected to the hydraulic system provided for

the hydraulic cylinder.

  In a particularly advantageous embodiment, the hydraulic cylinder and the master cylinder (s) are grouped in a hydraulic control system. This offers the

  possibility of controlling, simultaneously with the elevation, the inclination of the load carrier or of adjusting certain parameters.

  It is advantageous that a bent lever mounted in the control unit is connected to a pivoting lever, in particular in the form

  bow, pivotally mounted in the holder assembly

  load and articulated on a rod, namely via

  a joint bar respectively articulated at its ends, and that the master cylinders are mounted on the bent lever.

  This results in a particularly simple construction for the connecting rods since it suffices, in principle, to provide a single bent lever with a splice and a

  pivoting lever to allow a large number of adjustments.

  It is in particular this embodiment which creates a double guide between the control unit and the load-carrying assembly, namely on the one hand by the splint between the bent lever and the pivoting lever and, on the other hand , by a support roller mounted at the free end of the bent lever and which can be brought into contact with a slide in the load carrier assembly and moved thereon or also be released from the slide. We thus find ourselves in the presence of a double support and an articulated polygon of a particular type because the association of the articulated support elements is modified in service. This articulated polygon however offers the advantage of a

  stable lateral guidance and highly adaptable.

  It is then advantageous for the slide to be oriented parallel to the horizontal parts of the fork.

  In addition, in an advantageous embodiment, the splint and the master cylinder or its piston rod are mounted so as to be able to rotate around a pivot located in the corner.

  of the angled lever, the angle being open towards the load-carrying assembly.

  Such a connecting rod offers numerous possibilities for adaptation. However, it is also important here to limit the active force which provides the control.

  This is why it is advantageous for the pivoting levers

  have unequal arms and the arm length of the

  The rod on which the rod is articulated is approximately half that of the lever arm directed towards the splint.

  In this context, another particularly advantageous characteristic is that the splint has approximately the same length as the articulated arm of the bent lever and that the bent arm of the lever carrying the roller.

  support is about half as long.

  O10 A forklift, in particular a carriage of the kind described above, with lateral vertical slides on the control unit or the load-carrying assembly and with guide rollers moving in these slides on the assembly load or support is advantageously ca15 characterized in that respectively a single guide wheel is disposed on each side in the lower region of the vehicle and that the upper guide of the three-point guide thus produced is provided by the link of the rod hydraulic cylinder piston with load carrier assembly. This results in an original three-point attachment in the sense that only lower guide rollers, in particular with the same axis, are guided in U-shaped profiles and that the piston rod of the hydraulic cylinder is mounted so as to prevent any deviation. This creates the prerequisite for a stable and spill-free construction, but which also leaves many adjustment possibilities thanks to

the layout of the master cylinder.

  With regard to the upper connection between the piston rod of the hydraulic cylinder and the load-carrying assembly, it should be noted that this connection is neither movable nor pivoting. It is advantageous to connect the hydraulic cylinder and the master cylinder to a hydraulic pump by means of a pilot valve and to have a connection line between the hydraulic cylinder and the pilot valve for the master cylinders which has a non-return valve closing in the direction of the hydraulic cylinder and which can be connected, as desired, in the direction of entry or exit of the master cylinder. In the particularly preferred embodiment of the invention, it is then also provided that a tilt switch is inserted in the control system for the

  hydraulic cylinder and / or master cylinder.

  The implementation of such a tilt switch promotes automation of the system, that is to say that even in

  normal service, a setting is automatically obtained which corresponds to the normal operating regime.

  According to another particular characteristic of the invention which also relates to the description above, the connection pipe can be connected immediately to

  the pilot valve for the master cylinders by adjusting the pilot valve for the hydraulic cylinder when the latter is blocked. Thus is established the connection between the hydraulic cylinder and the master cylinders. 20

  A third pilot valve is then provided for regulating a return to the pump.

  In the preferred embodiment of the invention, the connections to the working volumes of the master cylinders pass, taking into account the above considerations, through adjustable throttles and non-return valves mounted in parallel, including that provided for connecting the volume of control for the entry of the master cylinders opens in the direction of said control volume, while the other non-return valve placed in the connection of the other control volume closes in

  direction of it. This results in a simple construction.

  It is then advantageous for the pilot valves to be able to be magnetically controlled, two magnets being provided for actuating the pilot valve of the master cylinders with regard to the connections for the admission and evacuation of the hydraulic fluid. , while a zero position of this pilot valve connects the connections of the master cylinders to the flow. For pilot valves, this solution is considered to be well known per se in another context, but according to the invention, there is preferably provided an actuating device, in particular in the form of a cam combator for connecting or disconnecting the pump according to the desired operating mode and to activate at the same time magnets selected for the actuation of the pilot valves, an operating mode of the only pilot valve 10 for the return to the pump and with the pilot valve for the masters -cylinders being provided for normal service with mobile parallel adjustment of the forks, while another operating mode is provided with simultaneous actuation of

  the pilot valve for the hydraulic cylinder and the return to the pump.

  The description which follows, with reference to the accompanying drawings by way of nonlimiting examples, will make it possible to understand clearly how the invention can be put into practice. 20

  Figure 1 shows, in section and with elements partially in section, a side view of a forklift to explain essential elements of the invention; FIG. 2 represents a view similar to FIG. 1, but in another service position in the direction of a so-called normal lifting; FIG. 3 represents a view similar to FIG. 1, but 30 with the use of particular adjustment means described for a different adjustment from the normal lifting; FIG. 4 represents a view similar to FIG. 3, but for the explanation of another adjustment of the load carrier relative to the rolling plane, in particular in the form of a ramp; FIG. 5 represents a section of FIG. 1 along the line V-V, seen from the left side of FIG. 1: FIG. 6 schematically represents a hydraulic control circuit for the embodiment corresponding essentially to FIGS. 1 to 5; FIG. 7 represents a diagram of the connections of an electrical circuit in combination with FIGS. 1 to 6; FIG. 8 shows schematically and in section, with elements partially in section, a side view of a forklift truck according to the invention for the explanation of the essential elements for another variant; FIG. 9 shows a view similar to FIG. 8. but in another service position; FIG. 10 represents an adjustment of the forklift truck corresponding to FIG. 3, but with an adjustment of the load carriers modified by the construction according to the invention; FIG. 11 shows another service position in accordance with FIG. 8 for the explanation of another possibility of adjustment; FIG. 12 schematically represents a hydraulic control circuit for the explanation of the realization of the functions according to FIGS. 8 to 11. 30 In fig. 1 to 12, the same elements have the same references. The forklift consists of a control unit 1 with a drive motor 2 for a steerable driving wheel 3. The control unit 1 could be fitted with a driver's seat and suitable control devices as well as sources of energy for training. In

  the embodiment, the description relates to a guided forklift provided with a drawbar 4 which comprises

  a control head 5 with handles and levers

  command to trigger the various functions.

  In the control unit 1 is fixedly mounted a hydraulic cylinder 6. It is fixed, for example, on a support 7 on a stiffening surface 8, so as to be able to rotate, if necessary, laterally around a pivot 9 placed in the longitudinal direction, in case the rolling plane presents inequalities in the transverse direction. This is a

advantageous configuration.

  The extractable piston rod 10 is secured to an en15 seems load-bearing 11il movable in height, the engagement of a pin 12 of the piston rod in a corresponding housing 13 being clearly visible. On this point, the piston rod 10 is part of the load carrier assembly movable in height and determines the displacement in height. 20 Outside the control unit are respectively two U-shaped profiles 14, 15 (fig. 5) vertical open towards the outside. They form vertical slides which, however, only extend over approximately one third of the height 25 of the vehicle and of the control unit 1 thereof. They can also be shorter depending on the height guide of the load carrier assembly. Inside these slides, a guide roller 16, 17 respectively moves, which is mounted, for example, so that it can rotate freely on the load-carrying assembly which covers the slides externally. The guide rollers 16, 17, at the bottom, and the housing for the guide pin 12, at the top, then create a non-pivoting three-point support which is considered to be

  being particularly advantageous and essential for vehicles of this kind.

  It appears from fig. 1 that a connecting linkage 18 is mounted on the stiffening surface 8. Such a linkage is provided on each side. It is fixed at the top so as to be able to rotate around a pivot 19 mounted transversely to the longitudinal axis of the vehicle and it comprises, on this fixing, a bent lever 20 with two arms 21, 22 of different lengths. The arm 22 shorter and distant from the pivot 19 carries a support roller 23 for which a slide

  24 is provided on the load carrier assembly 11. In normal service, this slide 24 extends practically parallel to a rolling plane and in any case parallel to a load carrier 25 in the form of horizontal parts of a fork.

  At the angle point 26 of the bent lever 20 is also mounted a pivot 27 to which the adjustment device is attached either directly, or by means of a cam or a bent lever; in the preferred embodiment of the invention, a piston rod 28 of a master cylinder hereinafter designated by 29, on the one hand, and a splint 30 articulated on a pivot 31 with a pivoting lever 32 in the form of arc, on the other hand, are articulated on this pivot 27, said pivoting lever 20 being able to turn in turn around a pivot 33 mounted on the load-carrying assembly 11. The pivoting lever 32 with two arms of different lengths communicates with its shortest arm, by means of an articulation and a pivot 34, with a rod 35 which is articulated, below the load carrier 25, in particular below the different branches of the fork, with a support 36 for casters 37. The support 36 is shaped in particular as a pivoting lever mounted on a pivot 39 in a horizontal part of the fork 39 of the load carrier and around which a pivo30 aunt 40 attachment can rotate whose other end is attached rigidly rotating in support, in particular lever

swivel 36.

  It goes without saying that it is also possible to provide an angled lever or an adjustable cam pivotally mounted at one end, like the master cylinder 29 in the control unit. Where applicable, a cable control or a

  rod can also be mounted directly on pivot 27.

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  This also makes it possible to produce a position according to FIG. 2 in which the pivoting lever 36 with the roller 37 is pivoted outwards when the piston rod 10 is out and the master cylinder 29 remains in its functional position, that is to say with the piston rod locked. The master cylinder 29 is mounted in the control block

  so as to be able to rotate around a transverse pivot 41.

  It appears from a comparative examination of Figs! and 2 that the described or10 ganes offer the possibility of normal actuation, the arc curvature of the pivoting lever 32 being chosen so that the bent lever 20 can be moved with the

  support roller 23 inside the curvature. The introduction of the master cylinder 29 as a support for the

  connection linkage 18 enables priority control to be carried out in the course of the functions.

  While fig. 1 and 2 represent a normal operating mode, FIG. 3 relates to a modified operating mode in the sense that the rolling plane 42 is inclined relative to a deposit area 43 for a pallet 44. In this situation, the rollers 37 with the supports 36 retracted are located with respect to the load surface 25 or of the fork 39 in the retracted position, the drive wheel 3 then overall occupying a tilting position relative to the rolling floor 42. This tilting position results from the fact that when the cylinder rod of lifting is out, the master cylinder 29 the forklift 30 being equipped with two master cylinders mounted on each side, or a single one connected by a cross to the two lateral linkages 18 - took out its piston rod 28 , thus moving the corner point 26 with the pivot 27 in a pivoted position relative to FIGS. 1 and 2. This pivoting position 35 is further regulated by the fact that the support roller 23 now moves on the slide 24 so that a completely free pivoting of the pivoting lever 20

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  around its pivot 19 is impossible and that the adjustment of the pivoting is determined, on the contrary, by the slide 24.

  In such an embodiment, the splint 30 has the effect that even when the rollers 37 are loaded, the support 36, in particular the associated pivoting lever, remains in its

retracted position.

  It is obvious that in a system according to FIG. 3, the 10 load carrier, and in particular the horizontal part 39 of the

  fork, can easily engage in pallet 44.

  This engagement movement is retained without resistance even when the machine approaches the pallet 44 on the inclined rolling area 42, the hydraulic cylinder 6 then coming into action to compensate for the parallel guidance of the branches of the fork 39 or a similar load carrier, and this in that its piston rod 10 which carries the load carrier assembly 11

is back.

  Figs. 3 and 4 show comparable embodiments on this point, but in which the support roller 23 occupies different positions on the slide 24, FIG. 4 showing a favorable example of the fact that the angle of the bent lever 25 just follows the corner 45 of the load-carrying assembly 11. If, in the embodiment according to FIG. 4, the master cylinder 29 returned its piston, this would result, on the one hand, in a descent of the load-carrying assembly 1il and-,

  on the other hand, also an output from the support wheel 37. 30 These are various effects of this particular configuration.

  Fig. 5 shows that there is provided at the bottom, in addition to the external guide, two bars 35, 35 'which are clamped by a lever pivoting in an arc 32, 32', 32 ", 32" '. Each pivoting lever is connected to a splint 30, 30 ′, the other articulation of which is at 27 or even 27 ′, where the piston rods of the master cylinders 29, 29 ′ are also articulated. The integration

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  of the splint in the bearings with the pivots 27, 27 'leads to a controlled connection with the bent lever 20, 20' of the

genre previously described.

  Fig. 5 also highlights a particular connection without play 46 to be compared with the other aforementioned advantages. The hydraulic cylinder 6 and the master cylinder 29 are also shown in FIG. 6. The hydraulic cylinder 6 has only one connection 47 for the pressurized fluid, while the master cylinder 29 is provided with two connections 48, 49 which respectively comprise an adjustable throttle 50, 51 and a non-return valve 52, 53 mounted in parallel. In this context, the volumes of the cylinder can be controlled, as desired, via the pipes.

  54, 55, the throttle conformations indicated allowing adaptations.

  The two supply lines 54, 55 only work firstly as a function of the fact that a pilot valve 56 is actuated according to an instruction for the re-entry or exit of the master cylinder produced by control magnets 57 , 58. These control magnets 57, 58 are actuated by a command transmitter not shown, possibly also in the form of a cam combiner or of various coupled levers. The arrival of the pump is then controlled by means of another pilot valve 59 mounted upstream of the hydraulic cylinder 6. A junction pipe 60 is connected, by means of a non-return valve 61 opening in direction of the pilot valve 59, at the inlet of pressurized fluid 47 and delivers the pressurized fluid, according to the setting of the

  pilot valve 59, on either side of the master cylinder 29.

  A backflow is prevented by the non-return valves 52, 53, 35, even when the pilot valve 59 is in its middle neutral position.

  The pilot valve 59 provides for connection via the junction line 60, with simultaneous supply of the hydraulic cylinder, when the pilot valve 56 is adjusted accordingly, actuation as a function of the cross section of the piston, d on the one hand, and in overregulation thereof, on the other hand, which may depend on the adjustment of the throttles 50, 51. For another position of the pilot valve 59, the working space of the hydraulic cylinder 6 is blocked and

  the pressure of the pump is sent directly to the pilot valve 59 via the junction pipe 60.

  Pilot valve 59 can be moved against the force of a

  spring 63 by means of an actuating magnet 62.

  A third pilot valve 67 which can be moved against the force of a spring 69 by an actuating magnet 68 is connected to the supply line 64 coming from the pump via a bypass 66. Due to '' an integrated non-return valve 70, it represents a barrier, as in the position indicated, or else its actuation allows, thanks to a passage 71, a flow, by a constriction

  72, to a reservoir 73 which also supplies the pump 65.

  This allows first of all, when starting the system, to take out the hydraulic cylinder 6, a supply of the master cylinder 29 can however be obtained at the same time, depending on the pressure, by overcoming the load of the valve. non-return 61, and this as a function of the adjustment of the pilot valve 56. In this regard, it is perfectly possible, in an adjustment position, to cause a withdrawal and therefore a particular adjustment of the pivoting lever or of the support 35 so as to then allow the performance of the functions described above. The purpose of the pilot valve 67 is to lock or cancel a certain position, while the pilot valve

  59 allows the actual lifting operation. Feeding is only possible in the upward direction, while

  say that a descent requires a corresponding switching of the pilot valve 67 to then also allow a return by the bypass 66. In the indicated position of the pilot valve 59, the junction pipe is not inserted in the return. This communication is only established when the pilot valve 59 is also actuated in such a way

  that a passage 74 would authorize the return.

  Fig. 7 shows a formal diagram with the insertion of a tilt switch 75 which is also formally indicated in FIG. 2 and which is placed alternately upstream of the actuating magnets 68 and 58. In the series circuit 76 is also interposed the motor 77 for the pump 65. A certain switching or blocking condition is thus created by the fact that the actuating magnet 68 can be engaged when tilting in one direction so that

  the return via passage 71 is open, but moreover that the pump 65 is stopped at the same time and that the excitation circuit of the actuating magnet 57 is cut.

  When tilting in another direction, the actuating magnet 68 is inactive, but the motor 77 for the pump 65 remains connected, as is the actuating magnet 58 so that the pilot valve 56 can be move in the same direction as the piston rod of the master cylinder 29 so as to achieve a service position as indicated in figs. 3 and 4. The inclination of the rolling plane 42 30 relative to the horizontal is thus compensated and the

  load arm or the fork load carrier 39 is automatically brought into a horizontal position.

  For the embodiment according to FIGS. 8 to 12, it should be noted that in FIG. 8 the load-carrying assembly 11 is in an elevated position relative to the control unit 1, while it is in the low position in the

fig. 9.

  Away from the pivot 38, the pivoting lever comprises another pivot 40 on which a bar 35 is articulated, the other end of which is pivotally connected to a linkage element 32 which can be oriented by means of a pivot 34. This element of linkage can rotate around a journal 33 mounted on the load-carrying assembly 11 or also in the region of the load-carrying carrier 25. It carries at its other end a support roller 78 which rests on a transverse element 79 which is fixed in the control unit 1. Since the load carrier assembly 10 rises or falls with respect to the control unit 1, depending on the actuation of the hydraulic cylinder,

  the relation of height of the pin 33 with respect to the transverse element 79 changes. Therefore, the linkage element pivots and the support roller 78 ensures a reduction in friction.

  While in fig. 8 the load carrier assembly 11 is in the raised position and that the pivoting lever 36 is extended to support the load carriers 25 in the state also shown 20 at their anterior ends, in FIG. 9, the load-carrying assembly 11 is in the low position so that the support roller 78, for example; is in a higher position than the pivot 34. Thus, the linkage element 32 has a larger overhang to the left relative to the section 79 so that the pivoting lever 36 with the roller 37 mounted on it is retracted under the load carrier 25. This is therefore in its position

  low above the haulage area.

  It goes without saying that the systems comprising the pivoting lever 36, the bar 35 and the linkage element 32 are provided on each side of the forklift equipped with two

  lever arm as load carrier 25.

  Figs. 8 and 9 show a particularly advantageous conformation of a bar of variable length which is produced in the form of a cylinder-piston system. On the pivot 34 is then articulated a cylinder 80 in which the bar 35 as a piston rod with, at its end, a piston 81 is engaged in the cylinder 80. The bar 35 is then guided, on the one hand, by the sealing elements 82 on the piston, if necessary in the form of piston rings, and, on the other hand, by a sealed passage 83 at the entrance to the piston. he goes

  it is understood that additional guide members can also be provided.

  Figs. 8 and 9 show normal operation with a constant length of the bar 35 which is ensured by the fact that the volume of the cylinder 84 is supplied with pressurized fluid. The embodiment described is satisfied with a piston for being loaded unilaterally so that it suffices that the volume 84 can be supplied with pressurized fluid since the system under pressure, in particular in the inclined position of the lever pivoting 36 shown in the

  fig. 8 results in flexibility or inversion of the movement 20 in the event of discharge of the volume 84.

  Figs. 10 and 11 show the modification of the adjustment of the load carriers 25 relative to the running plane 85, 86. While in FIGS. 8 and 9 the rolling area is flat, the rolling plan 85 is a ramp which rises and at the end of which is a platform 87 on which is deposited

a pallet 88, for example.

  In fig. 10, the load-carrying assembly 11 is in the raised position, as in FIG. 8, which emerges from

  the position of the arcuate linkage element 32.

  However, the volume of the cylinder 84 is discharged in such a way that, under the effect of the weight, with pivoting of the pivoting lever 36 on the underside of the front end of the load carrier 25, the piston 81 is moved in the volume of the cylinder against the bushing 83. As a result, the tips 89 of the load carriers lower on the rolling area 85 or even

  on platform 87 so as to allow engagement by-

  done in pallet 88. Considering a horizontal rolling area 85, it is obvious that, starting from the position indicated in fig. 8, the tips of the load carriers 25 are

  lowered against the haulage area.

  In fig. 11, The drive wheel 3 is on a rising rolling section. The load carrier 25 is located on a rolling area 86 which follows it and which is essentially horizontal. In this situation, the load-carrying assembly 11 movable in height is moved upwards by means of the hydraulic cylinder 6, namely to a higher level with respect to the elements of the vehicle than that indicated in FIG. 9. As a result, the overhang of the linkage element

  32 to the left is slightly larger than in position 15 according to FIG. 9 in which the rolling area is flat.

  Thanks to this greater deviation, it is possible to orient the load carriers 25 parallel to the rolling section 86, and this even when the drive wheel 3 is in a lower position than in FIG. 9. Taking into account the load applied to the wheel 37, the tilt compensation is obtained, in addition, by the fact that, during the discharge of the volume of the cylinder 84, the piston 81 moves outwards in adapting to the differences in slope 25 of the rolling plane, that is to say that, in FIG. 11 he can

move to the left.

  These examples show adaptability with simplified means. The control circuit according to fig. 12, comprises the hydraulic cylinder 6 and two cylinders 80 with cylinder volumes 84 and pistons 81 in the left position, and the rod

piston 35.

  The hydraulic control circuit includes a pump 65 which is driven by a motor 77. The suction pipe

  of the pump 65 is brought into a tank 73.

  The supply line 64 goes from the pump to the hydraulic cylinder 6 passing through a non-return valve 90. Between the non-return valve 90 which opens towards the hydraulic cylinder 6 and said hydraulic cylinder are arranged two branches 91 5 and 92. The bypass 91 passes through a non-return valve 93 which closes in the direction of a pilot valve 94 which controls connections connected in parallel 95, 96 to the volumes of

cylinder 84.

  The pilot valve 94 can be moved unilaterally against the force of a spring 98 by means of an actuating magnet 97. In the position indicated, the actuating magnet 97 is currentless, that is to say say that it is disconnected from its excitation source so that the spring 98 pushes the pilot valve 94 into the position shown in which the cylinder volumes 84 are filled with pressurized fluid, which applies to different working positions following

fig. 8, 9, and 11.

  The cylinder volumes, with the front face of the cylinder at the end opposite to that with the bushing 83, communicate, via connection pipes 99,

  , with a return line 101 leading to the tank 73.

  This allows easy control of the cylinders 80 by the supply of a volume. However, during a switching of the pilot valve 94 following the excitation of the actuating magnet 97, the volumes of cylinders 84 are connected to the return line 101 by means of a throttle adjustable 102. This allows a progressive evacuation of the volume 30 of the cylinder 84. A constant defined by the throttle 102 has the effect of preventing sudden variations in the position of the load carriers and, on the contrary, of adjusting a constant adapted to the speed respective work. This working position with its actuating magnet 97 connected to its excitation source 35, for example an accumulator, is produced in the configuration according to FIG. 10 in which the machine rolls on a ramp with adaptation to a flat platform 87.

  The bypass 92 communicates with another return line 107 to the tank, by means of a pilot valve 103 with an actuating magnet 104 and a counter-pressure spring 105 as well as by means of a connection 5 adjustable 106.

  In the position indicated, the actuating magnet 104 is

  without current, that is to say that the hydraulic cylinder 6 is supplied. This is so for the working positions according to FIGS. 8 and 11.

  When the pilot valve 103 is switched, the hydraulic cylinder 6 can be emptied into the tank 73. This is the case for the working positions according to FIGS. 9 and 11. As regards fig. 11, an adaptation results precisely from the fact that, at the same time, the pilot valve 94 is located in the

position indicated.

  It also appears from this description that the diagram 20 of the connections can be designed in a simple manner because

  pump pressure is applied appropriately and because a discharge via bypass 92

  and the throttle 106 is braked in such a way that a sufficient pressure bypass remains when the cylinder volumes 84 are supplied.

  Reference 108 designates a throttle valve of

  overpressure to avoid overloading the pump.

  With regard to operation, it must be taken into account that, even when the hydraulic cylinder 6 is discharged following a switching of the pilot valve 103, it is possible, if necessary, to ensure sufficient supply via the bypass 91 when the pilot valves 94 are in the indicated position. For this, it should be taken into account that, according to fig. 9, the pivoting levers 36 are in their end-of-travel position. In addition, they are always charged, at least by the device. Furthermore, the throttle 106 ensures a certain limitation of the flow by the bypass 92. The piston surface of the pistons 81 is made with a section

  transverse smaller than that of the piston of the hydraulic cylinder 6.

Claims (11)

  1. - Forklift truck with an adjustable control block and, guided on it, a load-carrying assembly movable in height which can be adjusted in height relative to the control block by means of a hydraulic cylinder dis5 installed in the control block and which can be guided on the control block; below the load carrier arranged at a fixed angle with respect to the load carrier assembly, in particular load-carrying forks, being provided with movable castors in height and mounted in particular on a pivoting lever, including the wheel supports , in particular the pivoting levers, can be moved in height as a function of a vertical control system corresponding to the actuation of the hydraulic cylinder to allow adjustment of the height of the load carrier parallel to the rolling plane, characteristic that the connection linkage for the castors movable in height comprises an adjustment device (29; 80, 81) which can be actuated as desired and that the angular position of the load carrier (25) relative to the rolling plane can be modified at choice. 2. - Forklift truck according to claim 1, in which the pivoting levers can be moved by means of bars which extend respectively between a pivoting lever and a pivoting linkage element, characterized in that the length bars (35) serving as connecting rods between the pivoting levers (36) and the elements of   linkage (32) can be modified by the adjusting device (80, 81).   3. - Fork lift truck according to one of claims 1 or 2, characterized in that the adjusting device (29) is produced in the form of a piston-cylinder system (80, 81), the bars (35) shaped in piston rods being engaged respectively in a cylinder (80) which is articulated 35 on the linkage elements (32), and that a stress   at least one-sided piston (81) can be ordered to adjusting the piston rod.   4. - Fork lift truck according to one of claims 1 or 2, characterized in that the adjustment device is made mechanically in the form of a tensioning nut with threads opposite at its ends into which the sections are screwed rods, a cylinder being provided for each tensioner nut.   5. - Forklift truck according to claim 1, in which the connection linkage is a system of levers provided between the load-carrying assembly and the control unit and articulated with connection elements, in particular rods, for the roller supports, in particular the pivoting levers, characterized in that it comprises a mechanical adjustment device (29) in the form   a cable control or a lever system.   6. - Forklift truck according to claim 1, in which the connection linkage is a system of levers provided between the load-carrying assembly and the control unit and articulated with connection elements, in particular rods, for the roller supports, in particular the pivoting levers, characterized in that it comprises an adjustment device (29) in the form of at least one master cylinder pivotally mounted in the control unit (1) and the piston rod of which is articulated with a lever on at least one connecting rod. 30 7. - Forklift truck according to any one   claims 1, 5 and 6, characterized in that an angled lever (20) mounted in the control unit (1) is connected to a pivoting lever (32), in particular in the form of an arc, mounted in a directional manner in the load-carrying (11) and articulated assembly   on a bar (35), namely by means of a splice bar (30) respectively articulated at its ends, and that the master cylinders (29) are mounted on the bent lever (20), a double guide between the control unit (1) and the load-carrying assembly (11) being provided, on the one hand, by the splint (30) between the bent lever (20) and the pivoting lever (32) and, on the other hand part, by a support roller (23) mounted at the free end of the bent lever (20) and which can be brought into contact with a slide (24) in the load-carrying assembly (11) and moved on the latter.   8. - Forklift truck according to any one of claims 1 to 7, characterized in that the assembly   load carrier (11) movable in height is guided parallel on the control block (1).   9. - Forklift truck according to any one   of claims 1 to 8, characterized in that the upper link is fixed in translation and in rotation and that, when   the connection of the hydraulic cylinder (6) and the master cylinder (29, 80) to a hydraulic pump (65), by means of pilot valves (56, 59; 94), a junction pipe (60, 20 91) comprising a non-return valve (61, 93) closing in the direction of the hydraulic cylinder (6) is arranged, for the master cylinders (29, 80). between the hydraulic cylinder (6) and the pilot valve (56; 94), said junction pipe being able to   be connected, as desired, in the direction of re-entry or exit of the master cylinder (s) (29, 80).   10. - Forklift truck according to any one   of claims 7 to 9, characterized in that it comprises a   third pilot valve (67) for adjusting a return to the pump.   11. - Forklift truck according to any one   of claims 7 to 10, characterized in that the connections to the working volumes of the master cylinders (29) pass 35 by adjustable throttles (50, 51) and valves   non-return valve (52, 53) mounted in parallel, one of which (52) on the connection (48) of the control volume for the re-entry of the master cylinders (29) opens in the direction of this control volume, while the '' other (53) on the connection of   the other control volume closes in the direction thereof.   12. - Forklift truck according to any one of claims 1 to 11, characterized in that the pilot valves (56, 59, 67, 94, 103) can be actuated by   magnets, two actuating magnets (57, 58) being provided   for the pilot valve (56) and a magnet (62, 68, 97, 103) ensuring the actuation of the other pilot valves (59, 67, 94, 10 103), said magnets acting against a counterpressure spring (63 , 69, 98, 105).   13. - Forklift according to any one of claims 1, 2 or 3 to 12, characterized in that a hydraulic hy15 cylinder (6) is mounted on a support (7), on a surface of   stiffening (8), so that it can rotate laterally around a pivot (9).