EP4117978A1

EP4117978A1 - Motor-driven tracked pallet truck

Info

Publication number: EP4117978A1
Application number: EP21718162.7A
Authority: EP
Inventors: Joseph COLLIBAULT
Original assignee: RSA Concept
Current assignee: RSA Concept
Priority date: 2020-03-13
Filing date: 2021-03-11
Publication date: 2023-01-18
Also published as: WO2021181047A1; FR3108088A3; FR3108087A1; FR3108088B3

Abstract

Truck (100) having a frame (10) with an end wall (111) receiving the load (CH) and a shaft (20) terminating in a handle (21) and a control unit (22), the frame (10) is supported on two tracked modules (30) connected to the frame (10) by a rotary joint (31) in order to swivel independently of each other, from the side of the frame (10) away from the side of the end wall (111). Each tracked module (30) is connected to the frame (10) by a rotary joint (31) and an extension spring (50) creating a force resisting the collapse of the module (30) against the frame (10), the swivel range of the driven tracked module (30) being limited between a retracted position against the frame (10) and a deployed position defining the upright position of the frame (10).

Description

DESCRIPTION

Title: "MOTORIZED TRACKED TRANSPALETTE CART

FIELD OF THE INVENTION

The present invention relates to a forklift truck type having a frame with a backrest receiving the load and a handle terminated by a handle and a control box, the frame resting on two track modules as well as a means. drive of the crawler modules, controlled by a control box, the crawler modules being connected to the frame by an articulation to pivot independently of one another on the side of the frame opposite to that of the receiving backrest load.

STATE OF THE ART

Such a handling trolley is already known according to document FR 1755475.

The carriage according to this state of the art comprises modules forming a support polygon either for movement on a hard, smooth surface S, or for passing obstacles in motion with the driver, on the module side, in front of the carriage. When the driver is walking in front of the trolley, the modules are folded up to take the steps.

The carriage (FIGS. 8A, 8B) circulates resting on the two drive wheels of the modules in the folded position on hard surfaces which do not require caterpillars.

The trolley can also circulate on its tracks deployed so as not to be on loose surfaces.

For the passage of steps, the trolley is either driven by the driver walking behind the trolley (figure 8A) and in this case, although the two modules form a support polygon, the center of gravity is located beyond this support polygon and a non-negligible fraction of the weight of the load must be taken up by the driver.

If the driver walks in front of the trolley (figure 8B) while being normally turned over to face the load, the support polygon is variable depending on whether each module is only supported on its driving wheel, or that part of the track is in support at two points and thus forms a very limited support polygon which creates abrupt changes in the force required of the driver who is himself in reverse. This chaotic movement can confuse the driver. This adds to the risk of stumbling and tipping of the loaded trolley down if the center of gravity passes beyond the vertical plane of the transverse line of support of the trolley on the step.

The diagrams of FIGS. 8A-8B show the case of a handling trolley 200 according to the state of the art with tracked modules, retractable, that is to say which are blocked either in a rolling position, deployed. at a fixed angle between the frame and the module, or in the folded position.

Figure 8A shows the cart 200 in the deployed position moving up steps with the driver behind the cart.

Figure 8B shows the trolley in the folded position of the crawler modules passing the staircase steps with the driver in front of the trolley.

PURPOSE OF THE INVENTION

The object of the present invention is to develop a trolley-type handling trolley as described above making it possible to pass more easily and simply over obstacles in safety, in particular staircase steps, without risking rearward tilting, towards the bottom of the stairs.

DISCLOSURE AND ADVANTAGES OF THE INVENTION

To this end, the invention relates to a forklift truck type having a frame with a backrest receiving the load and a handle terminated by a handle and a control box, the frame resting on two tracked modules as well. that a means of driving the tracked modules, controlled by the control box, these modules being connected to the frame by an articulation to pivot independently of one another, on the side of the frame opposite to that of the backrest receiving the load, this handling trolley being characterized in that each crawler module is connected to the frame by an articulation and an extension spring creating a force opposing the folding of the module against the frame, the range of pivoting of the driven crawler module being limited between a folded position against the frame and a deployed position defined sant the upright position of the frame. The trolley according to the invention has the advantage of easily passing obstacles such as small random obstacles encountered on the circulation surface of the trolley, either steps or a set of steps. In all cases, the elastically variable inclination of the module (s) with respect to the inclination of the chassis, kept constant according to the choice of the driver, prevents the lifting of the module (s) causing a reaction on the inclination of the chassis and modifies this when the angle between the modules and the frame of the carriage is fixedly blocked, when the tracks constitute the support polygons.

This flexibility of passage is particularly important for the wise step of steps and the ascent or descent of a staircase since the driver will be able to maintain the handle of the trolley, in a "constant" manner without having to react to a push in the direction of the staircase. tilting towards the rear of the chassis as is the case with handling trolleys of the state of the art.

In other words, this absence of support polygon, due to the elimination of the blocking of the angle between the frame and the bearing surface of the crawler modules and the independence of the travel of the two modules considerably facilitates and secures the movement of the loaded trolley, on an uneven surface with obstacles and also the passage of steps or / and the climb of stairs both up and down.

According to another feature, the crawler module is a driven crawler module composed of a drive wheel on the articulation axis connecting the module to the frame and at least one idler wheel over which the track passes.

According to another characteristic, the extension spring (50) is chosen from the group comprising: a coupling spring, one end of which is connected to a fixing point of the frame and the other to a fixing point of the module, a tension spring on the articulation axis and one end of which is connected to an attachment point of the frame and the articulation of which is connected to an attachment point of the crawler module.

This embodiment of the extension spring as a coil spring or as a two-branch spring installed on the articulation axis constitutes a particularly flexible and effective solution.

According to another characteristic, the crawler module comprises an auxiliary wheel between the driving wheel and the return wheel, forming a the front a ramp with the return wheel and with the driving wheel and a support surface.

This form of the crawler module which addresses obstacles is of interest for the regularity of the maneuver of the trolley. The ramp makes it possible to absorb easily and almost continuously without slowing down the speed of movement, the passage of the tracked module (s). In the case of the passage of a step this also facilitates the rise by foot of the module along the counter step since the return wheel at the front of the carriage has a much smaller diameter than the diameter of the wheel. driving given the interposition of the intermediate wheel.

According to another advantageous characteristic, the backrest is formed of a folded or welded sheet metal box comprising a backrest having two sides folded at the square and a underside to receive in the lower part a motor unit (40) with an electric motor connected. by a differential with two output axes connected respectively to a driving wheel of each module.

This embodiment makes it possible to adapt the load receiving accessories to the backrest such as shovels, claws, forks which are very variable and which can be adapted to particular applications of the trolley if the latter is used for several loads of the type. particular, requiring for their grip and their maintenance of accessories adapted to their shape.

According to another characteristic, the driving wheel of the crawler module is chosen from the group comprising: a driving wheel incorporating an electric motor controlled to form the differential with the electric motor of the other module and managed by a controlled electric differential system by the common box, a driving wheel connected to an electric motor installed in the chassis and whose output axis is connected to the axis of the driving wheel, the two motors being coupled in differential, a driving wheel connected to a motor group formed of an electric motor connected at the output to a differential, the two output shafts of which are respectively connected to a driving wheel of one of the two crawler modules.

According to another advantageous characteristic, the handling carriage comprises a locking device controlled to block the angle of inclination between the frame and the two modules 30, integral in this inclination, this locking device being disengageable. This locking device ensures the pairing of the two modules and locks them in the deployed position corresponding to the upright position of the frame or to an intermediate position depending on the developments of the locking device.

These actuating means, for example, mechanical can be actuated with the driver's foot so that the latter can activate or neutralize the locking device of the two modules without having to let go of the handle. Such blocking of the angle of inclination of the chassis relative to the module can be useful for traversing certain segments of the route with the industrial truck loaded. At the end of the blocking necessary to facilitate the passage of this path segment, the driver releases the blocking again so that only the extension spring of each module ensures the suspension of the module as has been explained above. above.

According to another advantageous characteristic, the locking device is chosen from the group comprising:

- an electromechanical locking member associated with the extension spring of each module or

- a telescopic rod connecting the frame to each module and is locked on command in the tilting position of the frame in relation to the two modules, or else

- A double strut pivotally carried by the frame, being movable between a retracted position and a locking position pressed against a stop of each module.

These variants of the locking device are adapted to the different uses of the trolley. They improve the functionality of the truck and its use in difficult passages on a journey with the industrial truck loaded.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in more detail below with the aid of embodiments shown in the accompanying drawings in which:

[Fig. 1] very general block diagram of the industrial truck of the invention

[Fig. IA] explanatory detail of the diagram in figure 1

[Fig. 2] general diagram of the industrial trolley according to the invention and a practical variant of this trolley

[Fig. 3A] diagram of the industrial truck in front of the steps [Fig. 3B] Position of the carriage of figure 3A approaching the first step [Fig. 3C] industrial trolley of FIG. 3A in the step-up position

[Fig. 4] perspective view, front side, of an embodiment of an industrial truck according to the invention

[Fig. 5] perspective view, rear side, of the industrial truck of figure 4

[Fig. 6] side perspective view of the handling trolley of fi gure 4

[Fig. 7] side perspective view of the handling trolley of FIG. 1 in the folded position.

[Fig. 8A] diagram of a trolley according to the state of the art presented on stair treads in the pushed position

[Fig. 8B] explanatory diagram of the passage of stairs with the prior art carriage in the pulled position

[Fig. 9] another embodiment of an industrial trolley with blocking of the inclination angle of the chassis with respect to the modules,

[Fig. 10] diagram of a variant of the industrial trolley in figure

9,

[Fig. 11] diagram of another variant of the industrial truck in Figure 9,

[Fig. 12] diagram of another variant of the forklift in Figure 9 DESCRIPTION OF AN EMBODIMENT

Figure 1 is a very simplified block diagram of a motorized crawler truck 100, of the devil type, composed of a frame 10 with a shovel 11 and a handle 20 terminated by a handle 21, with a control 22 to manage the operation of the truck.

The frame 10 is carried by a pair of motorized modules 30 with a pin, each connected by a hinge pin 31 to the frame 10.

Each crawler module 30 pivots independently of the other with respect to the frame 10 around the articulation axis 31 while being connected to the frame by an extension spring 50 fixed to a point 51 of the frame 10 and to a point 52 crawler module 30.

The direction DC of the frame 10 with its extension formed by the handle 20 forms an angle (Q) with respect to the direction H of the flat surface S on which the carriage 100 travels. The module 30 makes a variable angle (a) between a DM direction linked to module 30 and DC direction of chassis 10.

The angles (Q) and (a) are defined with respect to a reference direction which is the horizontal direction H for the angle (Q) and a direction DM attached to each module 30 and passing through the articulation axis 31 of each module; thus it is simpler to measure the angle (Q) with respect to the horizontal H passing through the axis 31 which facilitates the comparison of the variable angle (a) with respect to the angle (Q) which is a priori constant according to the attitude of the driver of the carriage 100 because, by hypothesis, it can be assumed that the driver operates the carriage 100 by pulling it on the supposedly flat surface S while holding the handle 21 at the same height so that l 'angle (Q) remains constant.

The direction of orientation chosen by convention in the present description is the front AV located on the side of the driver holding the handle 21 and the rear AR which is the side of the load CH.

In circulation on a flat surface S, the angle (a) is also constant, equal to the angle (Q) up to a constant (according to the reference direction DM assigned to the module 30).

But when the motorized tracked module 30 passes over an obstacle, the angle (a) of one or both modules 30 changes during the passage over the obstacle while the module 30 which does not meet the obstacle, remains with a constant angle (a).

In the case of climbing stairs approached in parallel by the two crawler modules 30, the inclination (a) of the two modules varies substantially in the same way and the articulation axis 31 of the two modules remains horizontal.

This description assumes that the driver walks in front of the carriage 100 with his load CH, which is the usual case for movement on a surface that is not perfectly flat or for the passage of steps so that the obstacles are approached from the front of the modules at the end. 'op posed from the rear of the modules corresponding to the articulation axis 31.

The motorized tracked modules 30 consist very schematically of a drive wheel 32 and at least one return wheel 33 over which the track 35 passes.

The drive wheel 32 is driven in the direction of forward travel AV of the carriage or in reverse AR or in the opposite direction for the other drive wheel to describe a curve.

The caterpillar 35 is driven directly or indirectly by a controlled electric motor 36, with a differential drive of the two drive wheels 32 of the two modules 30. The drive wheel 32 directly integrates an electric motor. It can also be connected to a electric motor 36 associated with the driving wheel 32 but installed on the chassis 10 or else by a motor common to the two driving wheels, connected to the driving wheels by a differential. In these two cases, the movement is transmitted directly via the pivot axis which becomes the transmission axis or else via an axis passing through the articulation axis 31.

The passage of an obstacle such as a step M1 will be described with the aid of the detail view of FIG. 1A.

The forward movement of the module 30 is indicated by the arrow d-AV. When the front of the module 30 which corresponds to the return wheel 33 arrives against an obstacle represented by the step M 1, the module 30 is stopped by the counter step CM1 so that the caterpillar 35 loses its caterpillar function c ' that is to say that of a fixed surface with respect to the surface S and on which the wheels 31, 33 of the module 30 roll. The cord then becomes a ribbon driven in the direction of movement mvo shown by the arrow. The caterpillar 35 rubs on the surface of the counter step CM 1 which generates an FM reaction which lifts the return wheel 33 from its position 33-0 to an ascending position 33-1. This pivoting movement (Da) is made possible by the articulation of the module 30 around the axis 31 with compression of the extension spring 50.

The FM reaction only has to overcome a fraction of the weight of the load CH since this weight remains resting on the ground S via the wheel 31 and by the handle 21 held by the driver.

The pivoting movement of the module 30 is shown schematically from its initial position, by the axis 31 and the return wheel 33 (position 31-0, 33- 0) and an intermediate position (31-1, 33-1) until wheel 33 reaches the top of step M 1.

The movement for the passage of the following steps takes place in the same way.

During these different movements, the angle (Q) remains a priori constant depending on the attitude adopted by the driver.

FIG. 2 shows by comparison with the general presentation of the industrial truck 100 of FIG. 1, an embodiment which differs in the structure of the front of the module 30. In order not to complicate the description, the reference numerals of FIG. 1 have been kept to describe this variant of FIG. 2; the module completes the return wheel 33 with an intermediate wheel 34 so as to form at the front, a ramp 37 facilitating the passage of small obstacles while maintaining the efficiency of the passage of large obstacles, similar to steps and implementing the dynamic reaction generated by the stop that constitutes the obstacle to the advance of the module 30.

The pivoting of the module 30 against the thrust of the extension spring 50 considerably facilitates the flexible passage of small obstacles without this passage slowing down the movement of the module 30 alone or of the two modules 30 depending on the width of the obstacle to be crossed. .

Figures 3A-3C show the passage of the carriage on the steps M1- M3 of a staircase showing the variation of the inclination (a) of the modules 30 with respect to the angle (Q) of the frame 10 carrying the load CH.

The figures are shown with the practical embodiment of the module 30 of Figure 2 with a ramp 37 which implements the principle of free tilting of the module 30 described generally with the aid of Figure 1.

To approach an obstacle such as M1-M3 steps, the driver holds the handle 20 and thus the backrest 111 at an arbitrary angle (Q) depending on the position of the driver in the front AV who "pulls" the carriage 100 with a CG center of gravity load. The frame 10 with the handle 20 up to the handle 21 constitutes a lever whose point of support is the driving wheel 32. The weight of the load is distributed according to the lever arms between, on the one hand, the point of support and the center of gravity CG of the load and on the other hand between the fulcrum and the handle 30.

As the crawler modules 30 can pivot freely around their pivot axis against the action of the extension spring 50, when the front end of the module 30 arrives on an obstacle, by reaction, the front of the module rises up the face. of the obstacle by pivoting the module 30 independently of the angle (Q) of the DC direction which can be kept constant as a function of the driver's attitude alone.

Conversely, this means that the driver can hold the handle 21 in the most efficient and comfortable way and above all without having to kiss and bend as would be the case if the modules 30 were in their folded, fixed position, or even risk risking. to see the center of gravity CG of the load pass beyond the vertical of axis 31 of module 30 and thus tilt down the slope of the stairs as can be the case with a trolley handling whose plug modules define a support polygon. The independence of the inclination (a) of the crawler module 30 and of the direction of the chassis 10 allows the particularly efficient passage of occasional or repeated obstacles such as steps, or even a staircase, both up and down. .

Figures 4-7 show an embodiment of a handling trolley 100 according to the general diagram of Figure 1 and its schematic embodiment of Figure 2 for the structure of the track modules 30.

The handling trolley 100 according to the invention is composed of a frame 10 provided with a handle 20 with a guide and control handle and two crawler modules 30 connected to the frame 10 by an articulation pin 31. and by an extension spring 50 pushing the module 30 in the direction of the opening of the angle (a) between the DC direction of the frame / handle and the bearing surface of each crawler module 30.

The pivoting movement of the module 30 is free against the thrust of the extension spring 50 between two extreme pivoting positions corresponding to the standing position of the handling trolley (FIG. 4) and the position of the module 30 folded against the frame 10. The extreme or end-of-travel positions are materialized by stops, not shown.

According to this embodiment, the frame 10 is composed of a parcelepipedal body in folded sheet metal forming a bearing surface or backrest 111 for the load CH to be transported and provided with two sides 112 and a underside 113 formed by parts folded square. In the lower part, the frame 10 houses a motor unit 40 formed of an electric motor 41 connected to a differential 42, the two output shafts 43 of which carry the driving wheels 32 of the two crawler module 30 passing through the bearings 321 in the sides 112 of the frame and the sides 301, 302 of each module 30. The motor group 40 can also consist of two electric motors, the respective output of which is connected to the driving wheel 32 of the associated module 30, the two electric motors being controlled by an electronic differential constituting the slow equivalent of a mechanical differential.

The battery 44 is housed in the lower part of the frame 10 above the motor unit 40.

The back of the frame 10 is covered by a cover, not shown.

The backrest 111 of the frame 10 receives the load support accessories, not shown, such as a shovel like that of a hand truck or a specialized accessory depending on the shape of the load to be transported if the truck is intended for a dedicated application.

The handle 20 is integrated into the frame 10 in which it can be escalated to reduce its bulk for storage. The end of the handle 20 is provided with a handle 21 for guiding and steering the trolley and with a control box 22. The box 22 is provided with various control members, not detailed, of the motor unit such as the direction of rotation of the motor, the speed and, if applicable, the differential lock. It also features a display for operating parameters such as battery charge status 44.

The two tracked modules 30 are symmetrical and have identical structures, except for the elements of symmetry.

Each module 30 is formed on two sides 301, 302 with the bearings 321, 331, 341 receiving the axis of the drive wheel 32, that of the return wheel 33 and that of the intermediate wheel on which pass the pin 35.

The modules 30 have a structure identical to that of the modules 30 of FIG. 2, of which the driving wheel 32, the return wheel 33 and the intermediate wheel 34 are hidden by the sides 301, 302 and of which only the bearings 321, 331, 341 carried by the sides 301, 302 appear.

The sides 301, 302 are optionally joined together by cross members.

The front of the module has a ramp 37 formed by the track 35 passing over the wheels 33, 34 as shown in Figure 2.

By orientation convention, the front FR of the truck 100 is the side where the driver stands and the rear RE is the side of the backrest 111 and the load.

The carriage 100 can travel in both directions AV, AR, although on routes with possible obstacles, in particular up stairs, the direction of movement is preferably that of forward travel.

The two modules 30 are carried, free to pivot, by their respective drive axis; this connection is completed by the tension spring 50, one end of which is connected to the interior side 302 of the modules 30 and the other is fixed to the side 112 of the frame 10. The extension spring 50 is provided with two stops. limit switch, one to limit the folded position, close to its alignment with the frame 10 (his backrest 111) and the other so that the angle (a) is close to 90 ° but that the center of gravity CG of the empty carriage 100 remains slightly on the front side AV.

The wheels of the module 30 form with the track at the front, a ramp 37 between the intermediate zone and the return wheel 33 as well as a traffic surface between the drive wheel 32 and the intermediate wheel 34.

The module 30 supports the weight of the carriage 100 and that of the load CH on the driving wheel 32 due to the freedom of pivoting of each module against the action of the extension spring 50. Thus the carriage has no support polygon when loaded. It has only one vacuum support polygon for example to stand as it appears in Figures 4 and 5, the two extension springs 50 exerting a sufficient torque to maintain the frame 10 in the raised position, close to vertical and against the end stop as has already been described.

FIG. 9 shows another embodiment of the handling trolley 100 equipped with a device 60 for blocking the angle of inclination a of the frame with respect to the two modules 30.

The controlled blocking device 60 is connected by one end 61 to the frame 10 and by the other end 62 to the two modules 30 so as to block the angle of inclination a as appropriate in any angular position a or when the frame 10 is straightened (angle aq) in its usual maneuvering position. This upright position aq can be adapted to the use, the nature of the CH loads to be transported and the nature of the journeys to be made.

The locking device 60 is controlled by the operator to be activated on a path or a path segment of the carriage and then it is released again.

The locking device 60 is an electromechanical device or a mechanical device.

According to the variant of FIG. 10, the blocking device 60a is an electromechanical device combined directly with the extension spring 50 of each module in order to block the latter. According to the embodiment, the blocking is done either in the precise position of the angle of inclination aq corresponding to the upright position of the carriage, or in the chosen position, corresponding to the angle a at the time of the control of the block. cage. The control is carried out, preferably, from a control button 63 provided on the handle 21 so that the driver can activate the positive locking device 60 without having to let go of the handle 21, which, in so far as the locking of the tilt angle is done immediately and not in a timed manner, can only be done if the frame 10 is tilted precisely according to this angle aq. This inclination of the frame 10 is, for example, its inclination end-of-travel position.

FIG. 11 shows another variant of the blocking device 60b in which this device is not combined with the extension spring 50 of each module, but is a separate device, associated with the frame 10 and with each module 30. This variant is in the form of a telescopic rod 60b connected by a pivot 61b to the frame 10 and by a stop 62b to each module 30: it is provided with a mechanical blocking member 64b or electromechanical to block the length of the rod 60b according to the angle a of the carriage 10 in the upright position, or in an intermediate position, chosen by the driver.

This locking member 64b in the form of a lock can be controlled from the handle 21 if it is electromechanical or by a cable, or even directly with the driver's foot so that the latter does not have to let go of the handle 21.

Unlocking is done under the same conditions.

FIG. 12 shows another variant of the locking device 60c, mechanical. This device is formed of a double strut 60c as associated with the two modules 30; this double strut is connected by the pivot 61c to the frame 10. The strut 60c is kept escalated against the frame 10 in the rest position. It frees itself from this position to block the angle aq and come into abutment against a support 62c of each module 30. This double strut has, for example, a structure of H lying with two rods articulated by one end 61c to the frame. 10 and connected by a cross which secures them. This strut 60c is released from the foot to unhook from its rest position and come into the active locking position. Unlocking is done in the opposite way, also at the foot so as not to have to let go of the handle during the maneuver. NOMENCLATURE OF THE MAIN ELEMENTS

100 Trolley

10 Chassis

111 File

112 Sides

113 Bottom

20 Round

21 Handle

22 Control box

30 Track module

31 Articulation axis

32 Driveway 321 Landing

33 Idler wheel 331 Starter wheel axle

34 Intermediate wheel 341 Intermediate wheel bearing

35 caterpillar

36 Engine

37 Ramp

40 Motor unit

41 Electric motor

42 Differential

43 Output axes

44 Battery

50 Extension spring

51 Spring fixing point to frame

52 Spring fixing point to module CH Load CG Center of gravity of load H Reference direction DC Direction of carriage DM Direction of module (Q) Tilt of carriage

(a) Tilt of the module

S Floor area

M1 ... M3 Steps

Claims

1. Hand truck (100) of the hand truck type having a frame (10) with a backrest (111) receiving the load (CH) and a handle (20) terminated by a handle (21) and a control box (22) , the frame (10) resting on two crawler modules (30) as well as a means for dragging the crawler modules (30), controlled by the control box (22), the modules (30) being connected to the frame (10) by an articulation (31) to pivot independently of one another, on the side of the frame (10) opposite to that of the backrest (111) receiving the load (CH), handling characterized in that each track module (30) is connected to the frame (10) by an articulation (31) and an extension spring (50) creating a force opposing the folding of the module (30) against the frame (10), the swivel range of the driven, crawler module (30) being limited between a stowed position against the frame (10) and a deployed position defining the upright position of the frame (10) .

2. Handling trolley (100) with driven tracks according to claim 1, characterized in that the tracked module (30) is a tracked module, driven, composed of a driving wheel (32) on the axis of 'articulation (31) connecting the module (30) to the frame and at least one return wheel (33) on which the track (35) passes.

3. Industrial trolley (100) according to claim 1, characterized in that the extension spring (50) is chosen from the group comprising: a coupling spring, one end of which is connected to a fixing point (51) of the frame (10) and the other to a fixing point (52) of the module (30), a tension spring on the articulation axis (31) and one end of which is connected to a fixing point (51 ) of the frame (10) and the other of which is connected to an attachment point (52) of the crawler module (30).

4. Industrial trolley 100 according to claims 1 and 2, characterized in that the crawler module (30) comprises an auxiliary wheel (34) between the drive wheel (32) and the return wheel (33), and forming to the front (AV) a ramp (37) with the return wheel (33) and with the drive wheel (32) and a bearing surface.

5. Handling trolley (100) according to claims 1 and 2, characterized in that the backrest (10) is formed of a folded or welded sheet metal box comprising a backrest (111) having two sides (112) folded at right angles and a underside (113) to receive a lower part of a motor group (40) with an electric motor (41) connected by a differential (42) to two output shafts respectively linked to a driving wheel of each module (30).

6. Industrial trolley (100) according to claims 1 and 2, characterized in that the driving wheel (32) of the crawler module (30) is chosen from the group comprising: a driving wheel (32) incorporating an electric motor ( 36) controlled to form the differential with the electric motor of the other module and managed by an electric differential system controlled by the common box,

- a driving wheel (32) connected to an electric motor installed in the frame (10) and whose output axis is connected to the axis (31) of the driving wheel (32), the two motors being differential coupled ,

- a driving wheel (32) connected to a motor unit (40) formed of an electric motor (41) connected at the output to a differential (42) whose two output shafts (43) are respectively connected to a driving wheel (32) of one of the two track modules (30).

7 °) Handling trolley (100) according to claim 1, characterized in that it comprises a controlled locking device (60) to block the angle of inclination its (a) between the frame (10) and its two modules (30), this locking device (60) being disengageable.

8 °) Handling trolley (100) according to claim 7, characterized in that the locking device (60) is chosen from the group comprising:

- an electromechanical locking device (60a), associated with the extension spring (50) of each module (30).

- a telescopic rod (60b) connecting the frame (10) to each module (30) and locking itself on command in the tilting position (a) of the frame relative to the two modules (30),

- a double strut (60c), carried pivotally by the frame (10), movable between a retracted position and a locking position, pressed against a stop of each module (30).