WO1994011229A1

WO1994011229A1 - Pallet carrying trolley

Info

Publication number: WO1994011229A1
Application number: PCT/FR1993/001172
Authority: WO
Inventors: Bruno Barnier
Original assignee: Bruno Barnier
Priority date: 1992-11-13
Filing date: 1993-11-15
Publication date: 1994-05-26
Also published as: EP0707548A1; FR2698063A1; AU5567294A

Abstract

A pallet carrying trolley in which a wheel (2) can be raised or lowered relative to a lifting arm (1). A wheel control mechanism (2) moves the wheel from a lowered position (shown) to an upright position by means of the rotation of a rotational axis (3) of the wheel (2), combined with the at least partially vertical movement of the centre (C) of the wheel (2).

Description

PALLET HOLDER TROLLEY

The present invention relates generally to a pallet carrier trolley and more specifically a pallet trolley essentially comprising a main body mounted on an elevating rear steering wheel, two horizontal lifting arms connected to the main body and each of which is provided with a corresponding elevating front wheel, a rear wheel actuation means mounted on the main body and actuating the elevation of the elevating rear steering wheel, two front wheel actuation mechanisms each of which is mounted in one of the lifting arms and actuates the elevation of one of the front elevating wheels and of control bars, each of which connects the rear wheel actuation means and the corresponding front wheel actuation mechanism.

People who usually use pallet trolleys often have difficulty advancing the pallet trolley when the floor surface is not perfectly smooth or level. Indeed, the front wheels of a conventional pallet trolley have a relatively small diameter because the upper surface of the lifting arms of the pallet trolley must be able to lower to a relatively low height relative to the ground in order that these lifting arms can pass under a standard standard pallet. As the front wheel of a conventional pallet carriage is arranged below the upper surface of the lifting arm, its diameter is necessarily very limited. This is how any user of a pallet trolley often sees a sudden blockage of the pallet trolley when the latter is carrying a relatively heavy load. This blockage is caused by the blocking of one of the front wheels of the carriage, caused by a small hard object strewn on the ground, for example a pebble or a bolt, or by a very low step situated on the ground between two consecutive flat surfaces. These sudden blockages are harmful to the structure of the truck, cause unpleasant handling of the truck and are dangerous because they can cause the load to overturn.

An object of the present invention is to provide a pallet carriage in which the front wheels can roll more easily on hard foreign bodies present on the ground.

Another object of the present invention is to provide such a pallet carriage in which the front wheels can easily pass irregularities or steps of low height present on the ground.

Another object of the present invention consists in proposing such a pallet-carrying trolley which can also comply with the dimensional constraints resulting from the use of standardized pallets.

The invention therefore relates to a rolling mechanism intended to support and transport a load.

According to a characteristic of the invention, each of the two front wheel actuation mechanisms has kinematics which transforms the longitudinal displacement of the control bar into a corresponding displacement of the axis of rotation of the front wheel, this displacement being the combination: - of a rotation of the front wheel rotation axis around an axis substantially perpendicular to this front wheel rotation axis and oriented substantially in the longitudinal direction of the lifting arm, - and of a displacement of the center of the front wheel in a plane substantially perpendicular to the longitudinal direction of the lifting arm, whereby the point of contact between the front wheel and the ground remain substantially in a longitudinal vertical plane when said front wheel actuation mechanism changes from a lowered position to a raised position and vice versa. We can also say that this displacement of the wheel axis results from a combination of a rotation of the rotation axis (3) of the wheel (2) and a displacement of the center (C) of the wheel (2), this displacement having at least one vertical component.

The invention also relates to a pallet carriage comprising: a main body mounted on a rear steering and elevating wheel; two lifting arms connected to the main body and each of which is provided with a lifting front wheel; a rear wheel actuation mechanism mounted on the main body and actuating the elevation of the steerable and elevating rear wheel; two front wheel actuation mechanisms each of which is mounted in one of the lifting arms and actuates the raising of one of the front lifting wheels; and a control bar connecting the rear wheel actuation mechanism and the front wheel actuation mechanism.

According to a characteristic of the invention, said wheel actuation mechanism has kinematics which transforms the longitudinal displacement of the control bar into a corresponding displacement of the axis of rotation of the wheel, this displacement being the combination: - d 'a rotation of the wheel rotation axis about an axis substantially perpendicular to this wheel rotation axis and oriented substantially in the direction of travel, - and of a displacement of the center of the wheel in a plane substantially perpendicular to the direction of advance, where it follows that the point of contact between the wheel and the ground remains substantially in a vertical plane along the direction of advance when said wheel actuation mechanism changes from a lowered position to a raised position and vice versa. We can also say that this displacement of the wheel axis results from a combination of a rotation of the rotation axis (3) of the wheel (2) and a displacement of the center (C) of the wheel (2), this displacement having at least one vertical component.

According to an embodiment of the invention, each of the two front wheel actuation mechanisms is constituted by: a first wheel support on which the front wheel is rotatably mounted; a second wheel support on which the first wheel support is rotatably mounted; a third wheel support which is connected to the second wheel support by means of a first articulation whose articulation axis is substantially longitudinal and which is mounted movable relative to the lifting arm so that the first articulation moves along a first substantially transverse trajectory (X; Y); and a pivoting control means, the pivot axis of which is substantially transverse, this control means being actuated by said control bar and comprising a free end connected to the first wheel support by means of a ball-type connection.

According to another embodiment of the invention, the third wheel support is slidably mounted along guide bars arranged in a substantially transverse manner.

According to another embodiment of the invention, the third wheel support is pivotally mounted about a second articulation axis fixed relative to the lifting arm.

According to another embodiment of the invention, said first trajectory (X; Y) is inclined relative to a horizontal plane so that said first articulation moves towards down and transversely when said front wheel actuation mechanism moves from a lowered position to a raised position.

According to another embodiment of the invention, said first trajectory (X; Y) is inclined relative to a transverse vertical plane so that the longitudinal position of said first articulation approaches said pivot axis of said pivoting control means when said front wheel actuation mechanism changes from a lowered position to a raised position.

According to another embodiment of the invention, said pivot axis of said pivoting actuating means is inclined with respect to a horizontal plane so that the position of said ball-type connection along a transverse line and the position of said first articulation along this transverse line move in the same direction when said front wheel actuation mechanism passes from a lowered position to a raised position.

According to another embodiment of the invention, said pivot axis of said pivoting actuating means is inclined with respect to a transverse vertical plane so that the position of said ball-type connection along a transverse line and the position of said first articulation along this transverse line moves in the same direction when said front wheel actuation mechanism passes from a lowered position to a raised position.

These objects, characteristics and advantages, as well as others, will be better explained during the detailed description of exemplary embodiments which will follow, illustrated by the appended figures among which: Figures 1 and 2 are the same cross-sectional views of part of a pallet carriage according to the invention, this part of the pallet carriage including a device according to the invention, the rest of the pallet carriage not being shown because it can be of any conventional type; Figure 1 showing the carriage in the lowered position and Figure 2 showing the same carriage in the raised position; Figure 3 is a simplified bottom view of the pallet carriage portion of Figure 1; Figure 4 is a simplified side view of the pallet carriage portion of Figure 1; Figures 5 to 7 are the same perspective views, from below, of another embodiment of a part of a pallet carriage according to the invention, this part of the pallet carriage including a device according to the invention, the rest of the pallet carriage not being shown because it can be of any conventional type; Figure 5 showing the carriage in the lowered position and Figure 6 showing the same carriage in the intermediate position and Figure 7 showing the same carriage in the fully raised position; and FIGS. 8 to 10 are schematic cross-sectional views of the device respectively of views 5 to 7.

In FIG. 1, there can be seen, in cross section, a lifting arm 1 of a pallet-carrying carriage in which a front wheel 2 of the carriage is mounted, this wheel 2 being able to rotate about a wheel articulation axis 3. The lifting arm 1 has an inverted U-shaped cross section. The wheel 2 and the whole mechanism for rotating and controlling the position of the wheel 2 is housed inside the lifting arm 1. This mechanism is hereinafter called "front wheel actuation mechanism". A control bar 4 (more visible in FIGS. 3 and 4) can move longitudinally between a position offset towards the rear of the carriage (position corresponding to FIGS. 1, 3 and 4) and a position offset towards the front of the carriage (position corresponding to figure 2). This control bar 4 makes it possible to control the lowering or raising of the wheel 2. The front end of the control bar 4 is connected by a hinge 6 to the free end of a first control arm 8 of which 1 the other end is fixed to a rotating hub 10 which can pivot around a fixed support bar 12. One end of a second control arm 14 (visible essentially in FIGS. 2, 3 and 4) is also fixed to the hub 10 and this second control arm 14 is connected, at its free end, by a ball-type joint 16 to a third control arm 18 of a part constituting a first wheel support 20, the latter being described more in detail below.

On this first wheel support 20, the wheel 2 is mounted for free rotation by means of a ball bearing 22. This first wheel support 20 is mounted for free rotation on a second wheel support 24. A third support wheel 26 is connected, at one of its ends, to the lifting arm 1 by means of an articulation 28, so as to be able to pivot relative to the lifting arm 1 about a pivot axis substantially longitudinal 30 (visible in Figure 3). The other end of the third wheel support 26 is connected to a fourth control arm 32 fixed to the second wheel support 24, by means of another articulation 34, so as to be able to pivot relative to the second support wheel 24 around a substantially longitudinal pivot axis 36 (visible in Figure 3).

This front wheel actuation mechanism operates as follows.

In its retracted position (FIGS. 1, 3 and 4), the control bar 4 is pulled towards 1 • rear relative to the lifting arm 1. The monobloc assembly constituted by the hub 10 to which the first and second arms of are attached control 8 and 14 constitutes a pivoting control means 38. The pivoting control means 38 is rotated so that the free end of the first control arm 8 which is connected to the end of the control bar 4 is pulled towards 1 • rear relative to the lifting arm 1 and that the free end of the second control arm 14 is in the raised position. This position of the pivoting control arm 38 corresponds to that shown in Figures 1, 3 and 4. In this position, the relative positions in the space of the joints 34 and 16 are such that the wheel 2 is strongly inclined relative to on the ground 40. More precisely, this wheel 2 has its axis of rotation 3 which is situated substantially in a vertical plane perpendicular to the longitudinal direction of the lifting arm 1 (that is to say a plane situated in the plane of the sheet of Figure 1), and this axis of rotation is further inclined relative to the horizontal at a relatively large angle αl, for example between 50 ° and 80 °. It is understood that this wheel 2 can in these conditions be housed between the surface of the ground 40 and the inner face 42 of the lifting arm 1 so that the distance dl separating these two surfaces 40 and 42 is less than the diameter d2 of the wheel 2.

When the control bar 4 is actuated to be brought into its second control position in which it is pushed longitudinally towards the front relative to the lifting arm 1 (that is to say the position shown in FIG. 2), the pivoting control means 38 is rotated so that the free end of the first control arm 8 which is connected to the end of the control bar 4 is pushed forward relative to the lifting arm 1 and that the free end of the second control arm 14 is in the lowered position (position away from the surface 42 of the lifting arm 1). This position of the pivoting control arm 38 corresponds to that shown in FIG. 2. In this position, the relative positions in the space of the joints 34 and 16 are such that the wheel 2 is substantially vertical so that it can roll normally. on the ground 40. More precisely, this wheel 2 has its axis of rotation 3 which is situated substantially in a vertical plane perpendicular to the longitudinal direction of the lifting arm 1 (that is to say a plane situated in the plane of the sheet of Figure 2), and this axis of rotation is also substantially horizontal.

In the lowered position (FIG. 1), the articulations 16 and 34 are raised (brought closer to the surface 42 of the lifting arm 1), so that the center C of the wheel 2 is relatively close to the surface 42 of the lifting arm lifting 1 and relatively distant from the longitudinal median plane 44 of the lifting arm 1, and in the raised position (FIG. 2), the joints 16 and 34 are lowered (distant from the surface 42 of the lifting arm 1) and brought back towards the plane longitudinal median 44 of the lifting arm 1, so that the center C of the wheel 2 is relatively distant from the surface 42 of the lifting arm 1 and relatively close to the longitudinal median plane 44 of the lifting arm 1.

In other words, while the axis 3 of the wheel 2 rotates to pass from an inclined position (FIG. 1) to a horizontal position (FIG. 2), the center C of wheel 2 moves along a certain trajectory so that it moves away from the surface 42 of the lifting arm 1 and that at the same time it approaches the longitudinal vertical median plane 44, and vice versa , i.e. a rotation in the opposite direction of the axis 3 implies a displacement in the opposite direction of the center C. It follows from this that, during the lowering or raising of the lifting arm 1 (passage of the Figure 1 to Figure 2 or vice versa) resulting from the actuation of the control bar 4, the point of contact P of the wheel 2 with the ground 40 remains substantially in the same longitudinal vertical plane of the arm 1 (not shown ), preferably in such a plane which is close to or coincident with the median longitudinal vertical plane 44 of the lifting arm 1. The consequence of such kinematics of the control mechanism of the wheel 2 is that the lifting arm 1 can s '' lower to a height above the ground dl less than the diameter d2 of l with front wheel 2 and that a movement of lowering or raising of the lifting arm 1 can be carried out without or practically without lateral movement of the lifting arm 1 (since the contact point P can remain in the same vertical plane) .

In fact, in the embodiment which has been described and according to an essential characteristic of the invention, when the axis 3 of the wheel 2 changes its inclination relative to the horizontal, the center C of the wheel moves according to a trajectory which is inclined with respect to the horizontal. According to a variant, this trajectory W can also be inclined relative to the vertical, this inclination making it possible to substantially maintain the point of contact P of the wheel 2 with the ground 40 in the same longitudinal vertical plane. When we say that the point P remains in the same longitudinal vertical plane, it is an approximation, because it is more exactly appropriate that this point P moves slightly transversely so that, in a transverse vertical plane (the plane of the sheet of FIGS. 1 and 2), the wheel 2 rolls without sliding on the plane from the ground 40 during the lowering or raising of the lifting arm l while this lifting arm 1 is lowered or raised by following a vertical path. To obtain this, one can play on the profile of the surface of the wheel 2 which can come into contact with the ground 40.

Figures 5 to 7 show another embodiment of the invention. In Figures 1 to 4 and Figures 5 to 7, the same parts or parts having the same function have the same reference. FIGS. 5 and 6 therefore show the lifting arm 1, the wheel 2 with its axis of rotation 3, the ground 40 and the control bar 4. The bar 4 is connected to a lever 50. The lever 50 comprises a first branch 51 and a second branch 52 substantially perpendicular. The bar 4 is connected by ball joint to the free end of the branch 51. A second lever 53 comprises three branches 54, 55, 56 and is pivotally mounted around an axis 57 along the branch 54. The lever 50 is mounted pivoting about an axis 58 along the branch 56. Two arms 59, 60 are mounted pivoting around the branch 55. A wheel support piece 61 is pivotally mounted on the free ends of the two arms 59, 60 and supports a hub 62 on which the wheel 2 is pivotally mounted and on which a wheel arm 63 is pivotally mounted, the free end of which is connected by a ball joint 64 to the free end of the branch 52.

The mechanism works as follows. We start arbitrarily from the lowered position of FIG. 5. The bar 4 is then pushed, which causes the pivoting of the lever 50. (like the length of the branch 51 is larger than that of branch 56, only the lever 50 starts to pivot about its axis 58 and therefore the lever 53 does not pivot around its axis 57. This movement brings the ball joint 64 closer to the branch 55, which causes the wheel support 61 to pivot while approaching the arms 59, 60 and becomes substantially vertical (FIG. 6). The wheel 2 has its axis 3 which therefore passes from a substantially vertical position (fig. 8) to a substantially horizontal position (fig. 9). Then, the continued pushing of the bar 4 can no longer pivot the lever 50 more because it comes into abutment (not shown) but then causes the pivoting of the lever 53 about its axis 57. This pivoting causes the pivoting simultaneous or in unison or in a single block of the two levers 50 and 53 (see passage from fig. 6 to fig. 7). This movement causes a downward translation of 1 • axis 3 of the wheel 2 (see passage from fig. 9 to fig. 10). An advantage of this embodiment is that first the wheel 2 straightens up and then the wheel 2 translates downward to lift the carriage even further. Another advantage is that all of the parts 50, 53, 59-63 and the wheel 2 form a completely assembled and sui assembly can be simply connected to the carriage 1 by an articulation pivoting the lever 53 around the axis 57 The bar 4 is simply fixed to the branch 51. This device therefore makes it possible to adapt to an existing conventional carriage which already has a pivot axis 57 and a bar end 4 connectable to a mechanism.

In a variant which can be produced from the first embodiment described in connection with FIGS. 1 to 4, the trajectory Y is an arc of a circle situated in a plane inclined relative to the vertical, this inclination being in the same direction than the inclination of the path X relative to a longitudinal vertical plane.

The invention is not limited to the embodiments which have just been described but encompasses all the variants in which a control mechanism for the front wheel of a pallet carriage performs the same functions as those of the invention, in that which concerns the combined movements of the axis 3 of the front wheel 2 and its center C.

One can for example envisage, without departing from the scope of the present invention, a third wheel support which would be constituted by a deformable parallelogram mechanism, a cam mechanism, a hydraulic cylinder mechanism, or the like.

One can also consider replacing the front wheel which is of large diameter with at least three wheels of small diameter coplanar, equidistant and mounted idly on a rotating hub. For example, it is thus possible to mount a well-known three-wheel rotating assembly which can easily, on two wheels, when the ground is smooth and which tilts by rotation of the hub in order to easily cross an ascending or descending step.

Claims

1. Rolling mechanism for lifting and transporting a load by rolling, comprising a wheel (2) and a control part (4), characterized in that it has kinematics which transforms the movement of a control part ( 4) in a corresponding displacement of the axis of rotation (3) of the wheel (2), this displacement being the combination:

- a rotation of the axis of rotation (3) of the wheel (2) about an axis substantially perpendicular to this axis of rotation of the wheel and oriented substantially in a direction of advance,

- And a displacement of the center (C) of the wheel (2) in a plane substantially perpendicular to the direction of advance, from which it follows that the point of contact (P) between the wheel (2) and the ground (40) remains substantially in a vertical plane in the direction of advance (44) when said wheel actuation mechanism passes from a lowered position to a raised position and vice versa.

2. Pallet trolley comprising: a main body mounted on a rear steering and elevating wheel; two lifting arms (1) connected to the main body and each of which is provided with a front lifting wheel (2); a rear wheel actuation mechanism mounted on the main body and actuating the elevation of the steerable and elevating rear wheel; two front wheel actuation mechanisms, each of which is mounted in one of the lifting arms (1) and actuates the raising of one of the front lifting wheels (2); and a control bar (4) connecting the rear wheel actuation mechanism and the front wheel actuation mechanism, characterized in that each of the two front wheel actuation mechanisms has kinematics which transforms the longitudinal displacement of the control bar (4) in a corresponding displacement of the axis of rotation (3) of the front wheel (2), this displacement being the combination:

- a rotation of the axis of rotation (3) of the front wheel (2) about an axis substantially perpendicular to this axis of rotation of the front wheel and oriented substantially in the longitudinal direction of the lifting arm (1),

- And a displacement of the center (C) of the front wheel (2) in a plane substantially perpendicular to the longitudinal direction of the lifting arm (1), where it follows that the point of contact (P) between the front wheel (2) and the ground (40) remains substantially in a longitudinal vertical plane (44) when said front wheel actuation mechanism moves from a lowered position to a raised position and vice versa.

3. Trolley according to claim 1 or 2, characterized in that each of the two front wheel actuation mechanisms consists of: a first wheel support (20) on which the front wheel (2) is rotatably mounted; a second wheel support (24) on which the first wheel support is rotatably mounted; a third wheel support (26) which is connected to the second wheel support by means of a first articulation (34) whose articulation axis (35) is substantially longitudinal and which is mounted movable relative to the arm lifting (1) so that the first articulation (34) moves along a first trajectory (X; Y) substantially transverse; and a pivoting control means (38) whose pivot axis is substantially transverse, this control means being actuated by said control bar (4) and comprising a free end connected to the first wheel support (20) by the via a ball joint type connection (16).

4. Trolley according to claim 3, characterized in that the third wheel support (26A) is slidably mounted along guide bars (54, 56) arranged substantially transversely.

5. Trolley according to claim 3, characterized in that the third wheel support (26) is pivotally mounted about a second articulation axis (30) fixed relative to the lifting arm d).

6. Trolley according to one of claims 3 to 5, characterized in that said first trajectory (X; Y) is inclined relative to a horizontal plane so that said first articulation (34) moves down and transversely when said front wheel actuation mechanism changes from a lowered position to a raised position.

7. Trolley according to claim 6, characterized in that said first trajectory (X; Y) is inclined relative to a vertical transverse plane so that the longitudinal position of said first articulation (34) approaches said pivot axis of said pivoting control means when said front wheel actuation mechanism moves from a lowered position to a raised position.

8. Trolley according to one of claims 3 to 7, characterized in that said pivot axis of said pivoting actuating means (38) is inclined with respect to a horizontal plane so that the position of said ball-type connection (16) along a transverse line and the position of said first joint (34) along of this transverse line move in the same direction when said front wheel actuation mechanism passes from a lowered position to a raised position.

9. Trolley according to one of claims 3 to 8, characterized in that said pivot axis of said pivoting actuating means (38) is inclined relative to a vertical transverse plane so that the position of said type connection ball joint (16) along a transverse line and the position of said first articulation (34) along this transverse line move in the same direction when said front wheel actuation mechanism moves from a lowered position to a raised position.