EP3286128B1 - Working platform with pothole protection - Google Patents

Description

The present invention relates to the field of mobile elevating work platforms (also referred to as PEMP) still commonly referred to as aerial work platforms. It relates more particularly wheeled aerial work platforms by means of which the aerial platform is supported on the ground and movable on it.

Aerial work platforms are machines designed to allow one or more people to work at height. They include a frame, a work platform and a lifting mechanism of the work platform. The work platform includes a tray surrounded by a railing. It is intended to accommodate one or more people and possibly also loads such as tools or other material, materials such as paint, cement, etc ... The working platform is supported by the lifting mechanism which is mounted on the chassis. In this case, the chassis rests on the ground through the aforementioned wheels. The lifting mechanism lifts the work platform from a lowered position on the frame to the desired working height, usually by means of one or more hydraulic cylinders. The motorization for moving the aerial platform to the ground is usually mounted directly on the chassis. This is also the case of the hydraulic unit supplying the aforesaid jack or cylinders, but it can also be mounted - when it includes one - on the turret of the lifting mechanism which is pivotally mounted on the frame to allow changing the orientation of the lifting mechanism and therefore of the work platform.

There are several types of work platform lifting mechanisms which are referred to as aerial work platforms. The invention primarily relates to, but is not limited to, scissor lifts and aerial work platforms with vertical poles.

In the case of scissor lifts, the lifting mechanism comprises centrally scissor-shaped beams, which scissors mechanisms are mounted one above the other at their ends which are pivotally connected to each other. reach the desired working height. The figures 1 and 2 illustrate an example of a scissor lift: the frame is referenced 1, the scissor lift mechanism 2, the work platform 3, the front wheels 4, the rear wheels 5 and the hydraulic actuator cylinder of the mechanism of lifting of the working platform 6. Depending on the models concerned, the maximum working height generally varies between 6 and 18 meters.

In the case of vertical boom lifts, the lifting mechanism is designed as an extensible mast with vertical parts sliding on one side. others to extend vertically to the desired working height. Their lifting mechanism sometimes comprises a turret on which are mounted the vertical sliding parts, the turret being pivotally mounted on the frame about a vertical axis in order to vary the orientation of the work platform relative to the frame. The work platform is mounted on the uppermost vertical part sometimes by means of a pendulum arm - that is to say an arm articulated to the vertical mast around a horizontal axis - in order to give more flexibility to the user to reach the working position. Depending on the models concerned, the maximum working height generally varies between 6 and 12 meters.

These two types of aerial work platforms have in common an increased risk of pouring when they move on the ground while their work platform is raised. This risk is likely to occur when one of the wheels rolls in a pothole in the ground or rises on a projection such as a curb. This risk is related mainly to the fact that their chassis is relatively narrow and their wheels have small dimensions unlike other types of nacelles with a wide chassis and larger wheels as is the case of articulated boom lifts and telescopic boom lifts which are generally intended for use exclusively outside and to reach greater heights that can go more than 40 meters.

To limit the risk that the aerial platform pays, it is known to arrange under the frame side bars commonly called protection bars against potholes. More specifically, such a bar is arranged under the frame, on each side, and extends horizontally over substantially the entire length between the front wheel and the rear wheel. A device automatically moves these two bars between a raised position, called an inactive position, and a lowered position, called an active position. One of these two bars - referenced 10 - is visible on the figure 2 where it is in the lowered position while they are not visible on the figure 1 because they are in the raised position under the frame 1.

When the work platform is lowered on the chassis, there is no risk that the aerial platform will not pour and the bars are in the raised position. In this case, the ground clearance is large enough to allow the aerial platform to cross, during its movement, obstacles such as potholes or curbs without the frame does not contact the ground.

When the work platform is raised, the bars are in the lowered position. The ground clearance is then significantly reduced. If a wheel of the aerial platform rolls in a pothole, the adjacent bar contacts the ground around the pothole. Consequently, the inclination of the chassis of the aerial platform is limited, thus preventing it from overturning.

There are essentially two technological approaches to achieve the device automatically moving the bars between their raised position and their lowered position.

A first approach is to use a mechanical connection between the lifting mechanism of the work platform and the bars, as well as springs. The operating energy of the lifting mechanism of the work platform is used to move the bars from the raised position to the lowered position. Examples of this approach are described by US 6,425,459 B1 , WO 2005/068347 A1 and CA 2 646 412 A1 . These solutions, however, are mechanically complex, especially since they must include a bar locking system in their lowered position to maintain this position if an external force tending to return to the raised position is applied to them.

The second approach is to use actuators assigned only to the actuation of the bars; they are therefore independent of that or those of the lifting mechanism of the work platform. Each bar is actuated by a respective actuator to move it from the raised position to the lowered position and vice versa, in particular according to the signal of a position sensor detecting whether the work platform is in the lowered position or not.

The figure 3 illustrates this approach as it is implemented on the machines of the Optimum range marketed by the applicant. Each bar 10 is secured to each of its longitudinal ends to a support 11 which is pivotally mounted to the frame 1 about an axis 12. The bars 10 pass from the raised position to the lowered position and vice versa by pivoting about the axes 12. Each bar 10 is moved between these two positions by a corresponding hydraulic cylinder 13 whose rod is mounted in pivot connection on the support 11 about an axis 14 and whose body is mounted in pivot connection on the frame around This solution is simpler than those of the first approach and provides reliable protection against the overturning of the aerial work platform, but it is still expensive because of the cost of the cylinders.

US 2002/0185850 A1 discloses another implementation of this second approach. Each bar is mounted to the frame by a first pair of links articulated together forming a first toggle mechanism and a second pair of links articulated together forming a second toggle mechanism. When the two toggle mechanisms are folded, the bar is in the raised position while the bar is in the lowered position when the toggle mechanisms are in the unfolded position. An actuator specific to each bar is mounted between the two toggle mechanisms to move them from the folded position to the unfolded position and vice versa. In unfolded position, the links of the toggle mechanisms are placed in abutment beyond the alignment position of their axes. In this way, the forces external to the aerial platform applied to the bars in the lowered position and which urge them to the raised position - which may correspond to the weight of the aerial platform - are countered by the toggle mechanisms, and not by the actuators. As a result, the force to be developed by the actuators is limited to that required to move the toggle mechanisms from the folded position to the unfolded position and vice versa. However, this solution is complex and expensive despite the use of more economical actuators.

EP 831 054 A2 discloses an aerial platform according to the preamble of claim 1. This is yet another implementation of this second approach, but using only one hydraulic cylinder to actuate the two bars. For this, the jack is mounted under the frame and extends parallel to mid-distance between the two bars, the cylinder body being fixed to the frame while its rod actuates pivotally the two bars through a mechanism of kneepad angle return which converts the movement of the rod parallel to the bars in a movement perpendicular to the bars. Although using only one cylinder, this solution is still complex and cumbersome because of the knee-lever angle mechanism.

Furthermore, it is known to arrange under the frame, just behind the front wheels and in front of the rear wheels, side bars protection against potholes which are fixed and very short, to reduce the ground clearance only locally. at the wheels. An example is given in WO 2013/059243 A1 . If this solution is simple and economical, it only moderately limits the risk that the nacelle pays. In addition, when moving with the work platform lowered, the aerial platform can hang on small irregularities on the ground such as a tar connection present for example on the door sills at the entrance of a building.

An object of the present invention is to provide a technical solution for protection against potholes for aerial work platforms that at least partially overcomes the aforementioned drawbacks. In one aspect, the invention aims to provide a solution that is both reliable while being simpler and more economical.

• un châssis monté sur roues pour le déplacement de la nacelle élévatrice au sol ;
• une plate-forme de travail ;
• un mécanisme de levage monté sur le châssis et supportant la plate-forme de travail pour la déplacer en hauteur ;
• deux barres latérales agencées sous le châssis, chacune étant mobile par rapport au châssis entre :
  • ∘ une position relevée ; et
  • ∘ une position abaissée dans laquelle la barre latérale dépasse du châssis en direction du sol ; et
• un actionneur affecté uniquement à l'actionnement des deux barres latérales pour les déplacer de la position relevée à la position abaissée et réciproquement.

To this end, the present invention provides a lifting platform, comprising:

• a chassis mounted on wheels for moving the aerial platform to the ground;
• a work platform;
• a lifting mechanism mounted on the frame and supporting the work platform to move it upwards;
• two side bars arranged under the frame, each being movable relative to the frame between:
  • ∘ a raised position; and
  • ∘ a lowered position in which the side bar protrudes from the chassis towards the ground; and
• an actuator assigned solely to actuating the two lateral bars to move them from the raised position to the lowered position and vice versa.

The lowered position of the side bars makes it possible to limit the risk that the aerial platform will overturn if a wheel rolls in a pothole during its displacement on the ground with the work platform raised. The fact that the actuator is assigned solely to the actuation of the two lateral bars is advantageous because, being distinct from the actuator (s) of the lifting mechanism of the working platform, it avoids resorting to a complex mechanical connection between the lifting mechanism of the platform and the side bars as is the case of the prior arts implementing the first approach described above. Moreover, the fact of using a single actuator to operate both bars is more economical and limits assembly operations compared to the prior art using two actuators as is the case of those implementing the second. approach described above.

According to an advantageous aspect of the invention, the actuator has two opposite ends through which it actuates the two lateral bars by varying the distance between the two ends, the actuator acting on each of the two side bars through another of the two ends and the actuator being maintained only through the two ends. As a result, the actuation mechanism of the bars is simpler, more economical and more compact compared to the teaching of EP 831 054 A2 mentioned above.

• chacune des barres est montée au châssis par le biais d'éléments de liaison et l'actionneur est maintenu au châssis uniquement par le biais desdits éléments de liaison ;
• les barres sont montées au châssis en liaison pivotante ;
• l'actionneur sollicite chaque barre en position abaissée contre une butée fixe respective du châssis ;
• dans la combinaison des deux caractéristiques précédentes, il peut être prévu qu'en position abaissée, le bord inférieur de chaque barre soit décalé par rapport à une verticale passant par l'axe de pivotement de manière à ce que les efforts extérieurs à la nacelle élévatrice qui s'exercent verticalement vers le haut sur le bord inférieur de la barre soient contrés par la butée fixe respective du châssis ;
• l'actionneur sollicite les barres en position relevée contre une butée fixe du châssis ;
• chaque barre est horizontale et s'étend entre deux roues latérales sensiblement sur toute la longueur séparant les deux roues latérales ;
• l'actionneur est un vérin ;
• l'actionneur est un vérin hydraulique ;
• le vérin s'étend horizontalement et perpendiculairement à la direction longitudinale du châssis ;
• l'actionneur s'oppose aux efforts extérieurs à la nacelle élévatrice agissant sur les barres qui tendent à les déplacer de la position abaissée vers la position relevée ;
• chacune des deux extrémités de l'actionneur est montée de préférence en liaison pivot sur l'une respective des deux barres ou sur une pièce sur laquelle est solidarisée l'une respective des deux barres ;
• chacune des deux extrémités de l'actionneur est montée en liaison pivot sur un support respectif auquel est solidarisé une autre des deux barres latérales, le support étant monté pivotant au châssis ;
• chacune des barres latérales est solidarisée au support respectif vers une de ses extrémités longitudinales, chacune des barres latérales étant en outre solidarisée vers l'autre de ses extrémités longitudinales à un deuxième support respectif monté pivotant au châssis ;
• l'actionneur actionne chacune des deux barres latérales par le biais d'un mécanisme à verrouillage respectif, chaque mécanisme à verrouillage ayant une position déverrouillée et une position verrouillée, l'actionneur actionnant les mécanismes de verrouillage pour les faire passer de leur position déverrouillée à leur position verrouillée et réciproquement, le passage en position déverrouillée ayant pour effet de déplacer les barres latérales en position relevée et le passage en position verrouillée ayant pour effet de déplacer les barres en position abaissée, les mécanismes à verrouillage en position verrouillée contrant indépendamment de l'actionneur tout effort extérieur à la nacelle élévatrice exercé sur les barres qui tendent à les déplacer de la position abaissée vers la position relevée ;
• la nacelle élévatrice est une nacelle élévatrice à ciseaux ou une nacelle élévatrice à mât vertical.

In preferred embodiments, the invention includes one or more of the following features:

• each of the bars is mounted to the frame by means of connecting elements and the actuator is held to the frame only through said connecting elements;
• the bars are mounted to the frame in pivotal connection;
• the actuator urges each bar in the lowered position against a respective fixed stop of the frame;
• in the combination of the two preceding characteristics, it can be provided that in the lowered position, the lower edge of each bar is offset relative to a vertical passing through the pivot axis so that the external forces to the aerial platform which exert vertically upward on the lower edge of the bar are countered by the respective fixed stop of the chassis;
• the actuator urges the bars in the raised position against a fixed stop of the frame;
• each bar is horizontal and extends between two lateral wheels substantially along the entire length separating the two lateral wheels;
• the actuator is a cylinder;
• the actuator is a hydraulic cylinder;
• the jack extends horizontally and perpendicular to the longitudinal direction of the frame;
• the actuator opposes the forces external to the lifting platform acting on the bars which tend to move them from the lowered position to the raised position;
• each of the two ends of the actuator is preferably mounted in pivot connection on a respective one of the two bars or on a part on which is secured one respective of the two bars;
• each of the two ends of the actuator is pivotally mounted on a respective support which is secured to another of the two side bars, the support being pivotally mounted to the frame;
• each of the lateral bars is secured to the respective support towards one of its longitudinal ends, each of the lateral bars being further secured towards the other of its longitudinal ends to a second respective support pivotally mounted to the frame;
• the actuator actuates each of the two side bars through a respective locking mechanism, each locking mechanism having an unlocked position and a locked position, the actuator actuating the locking mechanisms to move them from their unlocked position to their locked position and reciprocally, the transition to the unlocked position having the effect of moving the side bars in the raised position and the passage in the locked position having the effect of moving the bars in the lowered position, the locking mechanisms in the locked position counteracting independently of the actuator any force external to the aerial platform exerted on the bars which tend to move them from the lowered position to the raised position;
• the aerial work platform is a scissor lift or vertical mast aerial work platform.

• La figure 1 représente une vue en perspective d'une nacelle élévatrice à ciseaux avec la plate-forme de travail en position abaissée sur le châssis, la nacelle présentant des barres latérales de protection contre les nids de poule qui ne sont pas visibles car en position relevée sous le châssis.
• La figure 2 représente la même vue en perspective de la nacelle élévatrice de la figure 1, mais avec la plate-forme de travail levée et les barres latérales de protection contre les nids de poule en position abaissée (dont une seule est visible).
• La figure 3 représente pour une nacelle élévatrice à ciseaux des figures 1 et 2, le châssis et un système d'actionnement des barres latérales de protection contre les nids de poule selon l'art antérieur de la gamme Optimum de la demanderesse, les barres étant en position relevée, étant précisé que la partie du châssis correspondant aux roues avant est fictivement omise pour rendre visible le système d'actionnement des barres latérales de protection contre les nids de poule lequel est situé à un niveau du châssis un peu en arrière des roues avant.
• La figure 4 représente pour une nacelle élévatrice à ciseaux des figures 1 et 2, une vue éclatée du châssis et du système d'actionnement des barres latérales selon un mode de réalisation préféré de l'invention.
• Les figures 5 et 6 représentent respectivement une vue en perspective et une vue de face du châssis et du système d'actionnement des barres latérales de protection contre les nids de poule, les barres étant en position relevée, étant précisé qu'une partie du châssis est fictivement omise pour rendre visible le système d'actionnement des barres latérales de protection contre les nids de poule.
• Les figures 7 et 8 sont similaires à celles des figures 5 et 6, mais avec les barres latérales de protection contre les nids de poule en position abaissée.
• Les figures 9 et 10 représentent schématiquement une variante selon l'invention du système d'actionnement des barres latérales de protection contre les nids de poule, les barres étant en position abaissée et en position relevée respectivement.

Other aspects, characteristics and advantages of the invention will appear on reading the following description of a preferred embodiment of the invention, given by way of example and with reference to the appended drawing.

• The figure 1 represents a perspective view of a scissor lift with the working platform in a lowered position on the chassis, the platform having side bars for protection against potholes which are not visible because in the raised position under the frame.
• The figure 2 represents the same perspective view of the aerial lift figure 1 but with the work platform raised and the pothole protection side bars in the down position (only one of which is visible).
• The figure 3 represents for a scissor lift figures 1 and 2 , the frame and a system for actuating the pothole protection side bars according to the prior art of the Optimum range of the applicant, the bars being in the raised position, it being specified that the part of the chassis corresponding to the front wheels is fictitiously omitted to make visible the operating system of the pothole protection side bars which is located at a level of the chassis a little behind the front wheels.
• The figure 4 represents for a scissor lift figures 1 and 2 , an exploded view of the frame and the system for actuating the lateral bars according to a preferred embodiment of the invention.
• The Figures 5 and 6 respectively represent a perspective view and a front view of the frame and the actuation system of the pothole protection side bars, the bars being in the raised position, it being specified that part of the frame is fictitiously omitted to render visible the system of actuation of the lateral bars of protection against the potholes.
• The Figures 7 and 8 are similar to those of Figures 5 and 6 , but with the pothole protection side bars in the down position.
• The Figures 9 and 10 schematically represent a variant according to the invention of the operating system of the side bars of protection against potholes, the bars being in the lowered position and in the raised position respectively.

We will describe below a preferred embodiment of the invention with reference to figures 1 , 2 and 4 to 8 . The above description of the aerial lift figures 1 and 2 remains applicable in the context of this embodiment.

As visible on figures 1 and 2 , the aerial platform comprises an elongated chassis, mounted on wheels to allow the displacement of the aerial platform. The two narrow ends define the front AV and the rear rear of the aerial lift with regard to the direction of ground travel that two front wheels 4 and two rear wheels 5 give to the aerial platform.

The lifting platform comprises on each side side a bar 10 for protection against potholes. One of these two bars is visible on the figure 2 where is she in the lowered position while they are not visible on the figure 1 because they are in the raised position under the frame 1. Each side bar 10 is arranged under the frame 1 and extends horizontally over substantially the entire length between the front wheel and the rear wheel, whether in the lowered position or in position identified.

The system for actuating the bars 10 to move them in the lowered position and in the raised position will be described with reference to the Figures 4 to 8 .

Each bar 10 is secured to each of its longitudinal ends to a support 21 which is pivotally mounted to the frame 1 about a respective axis 22. The bars 10 pass from the raised position to the lowered position and vice versa by pivoting about the axes 22. Each bar 10 is moved between these two positions by the same actuator, in this case a hydraulic cylinder 30. This is assigned only to the actuation of the bars 10. The body of the jack 30 is mounted in pivot connection about an axis 33 on a support 21 of one of the bars 10. In this case, the body of the jack 30 has been lengthened by a rod 32 which is fixedly arranged on the body of the jack 30. The rod 31 of the jack 30 is mounted in pivot connection about an axis 34 on a support 21 of the other bar 10. In a variant, the rod 31 of the jack 30 and / or the body of the jack 30 are mounted - preferably in pivot connection - directly to the corresponding bar 10 or to a piece other than a support 21 to which the corresponding bar 10 is secured.

As it is visible Figures 5 and 6 when the rod 31 leaves the body of the jack 30, the distance between the two axes 33, 34 increases and rotates each support 21 about its axis 22 so as to move the bars 10 in the raised position. The pivoting of the bars 10 is stopped in the raised position abutting 40 against the frame 1.

As it is visible Figures 7 and 8 when the rod 31 retracts into the cylinder body 30, the distance between the two axes 33, 34 decreases and rotates each support 21 about its axis 22 in the opposite direction of the previous case, which causes the displacement of the bars 10 in the lowered position. The pivoting of the bars 10 is stopped in the lowered position by abutting at 41 - visible only on the figures 6 and 8 - against the chassis 1.

Alternatively, the jack 30 can be mounted to the supports 21 so that it is the output of the rod 31 which causes the displacement of the bars 10 in the lowered position and the retraction of the rod 31 which causes their displacement 10 in the raised position. .

As can be seen, the jack 30 extends horizontally and perpendicularly to the longitudinal direction of the frame 1, which limits the space necessary for housing the jack 30.

The jack 30 is only held to the frame by the supports 21 to which it is mounted, which simplifies assembly operations.

The hydraulic supply of the jack 30 is made by flexible hoses, which allows the cylinder body to move relative to the frame 1 when the rod 31 out or retracts.

In our example, the cylinder 30 is a double-acting cylinder. It is supplied with hydraulic fluid by means of two connectors 36, 37 mounted in our example on a housing 35. The housing 35 is itself mounted on the body of the jack 30 by two rigid tubes feeding each of the chambers of the jack 30 from the fittings 36, 37 via a respective nonreturn valve contained in the housing 35. These check valves advantageously provide security by locking in position the rod 31 of the cylinder 30 when it is not moving or in the case where the hydraulic supply circuit had to fail.

As a safety measure, a position sensor 50 is provided for each bar 10 to verify that it is in the lowered position. This makes it possible to trigger an alarm and prevent the platform from moving on the ground if one of the bars 10 is not in the lowered position when it should be. In this case, each sensor 50 cooperates with a surface of the support 21 of the bar 10.

It is advantageous for the lower edge 10a of the bars 10, when in the lowered position, to be offset towards the outside of the frame with respect to the vertical V passing through the axis 22 of pivoting of the support 21. In this way, the forces Fv external to the aerial platform exerted vertically upwards on the lower edge 10a of the bars 10 are directly countered by the frame 1 at 41 where the bar 10 is supported. It is therefore not the jack 30 against the vertical forces. It is the same F _LI efforts outside the lifting platform acting laterally on the bars 10 towards the outside of the chassis 1. On the other hand, the jack 30 against the forces F _LE outside the aerial platform that s exert laterally on the bars 10 towards the interior of the frame 1. This is advantageous because the lateral forces F _LE and F _LI are generally less than the vertical forces Fv, which makes it possible to use a less powerful jack 30 and therefore less expensive.

In general, the system for actuating the bars 10 is preferably dimensioned so as to be able to keep the bars 10 in the lowered position for vertical forces Fv exerted on each of them by at least half the weight of the aerial lift with his work platform loaded to his maximum allowed load. Likewise, the system for actuating the bars 10 is preferably dimensioned so as to be able to keep the bars 10 in the lowered position for lateral forces F _LE , F _LI exerted on each of them from less than one quarter of the weight of the aerial work platform with its working platform loaded to its maximum authorized load.

The cylinder 30 may be powered by the hydraulic supply circuit of the aerial platform which serves to supply the actuators of the lifting mechanism 2 and / or actuators controlling the orientation of the steering wheels 4 of the aerial platform. The jack can be classically controlled by a hydraulic distributor preferably electrically controlled. The dispenser can then be controlled by an electrical circuit depending for example on a position sensor - not shown - which detects whether the lifting mechanism 2 of the working platform 3 is in the lowered position and / or commands triggered by the operator at the control station of the aerial work platform.

There are several ways to manage the lowering and raising sequences of the bars 10. For example, the control circuit can cause the raising of the bars 10 in the case where a control movement of the aerial platform on the ground is triggered by the operator and that the aforementioned position sensor detects that the lifting mechanism 2 is in the lowered position. In the opposite direction, the control circuit can cause the lowering of the bars 10 in the case where a lifting control of the work platform 3 is triggered by the operator. If the position sensor of the lifting mechanism signals that the work platform 3 is raised and one of the position sensors 50 indicates that a bar is not in the lowered position, the control circuit prohibits the movement to the the platform and triggers an alert to the operator, for example by lighting a fault light on the control station.

The Figures 9 and 10 schematically illustrates a variant of the embodiment described above. Only the left part of the actuating system is shown, it being specified that the right part not shown is made in the same way, except that it is the body of the jack 30 which is connected to the corresponding support 21 in the same way that the cylinder rod 31 for the left part of the actuating system. We will mention below that the differences of this variant with respect to the previous embodiment. As before, the bars 10 are mounted pivotally connected to the frame about an axis 22. On the other hand, the jack 30 actuates each bar 10 by means of a respective locking mechanism. It is constituted in this example by two links 61 and 62. The rod 61 is mounted in pivot connection to the support 22 about the axis 63. At its other end, the rod 61 is pivotally mounted about the axis 64 at a end of the rod 62. The other end of the rod 62 is pivotally connected to the frame about the axis 65. The rod 31 is linked in pivot connection to the locking mechanism to the axis 64.

The figure 10 illustrates the unlocked position of the locking mechanism in which the rods 61 and 62 are in a folded position while the bar 10 is raised. The jack 30 moves the locking mechanism and the bar 10 when it leaves its rod 31.

When the jack 30 retracts its rod 31, it moves the locking mechanism in the locked position which is illustrated by the figure 9 . In this case, the axis 64 has exceeded the alignment position with the axes 63, 65 and one of the rods 61, 62 is in abutment against a stop 66 of the frame 1. In this way, the rods 61, 62 are in a self-locking position with respect to any external force exerted on the lifting platform exerted on the bar 10 which tends to rotate it from the lowered position to the raised position. In other words, in the locked position, the locking mechanism against these forces independently of the cylinder. Since the jack 30 does not intervene in maintaining the position of the bar 10 vis-à-vis these efforts, it can be a much lower power since it must only be able to actuate the locking mechanisms . In this case, it is possible to replace the hydraulic cylinder 30 with a pneumatic cylinder, see an electromechanical actuator.

Of course, the present invention is not limited to the examples and to the embodiment described and shown, but it is capable of numerous variants accessible to those skilled in the art. The actuator may be of any suitable type other than a hydraulic cylinder. Although particularly suitable for scissor lifts and vertical boom lifts, the invention can be applied to any other type of mobile elevating work platforms, including towed or pushed aerial work platforms to move them to the ground.

Claims (15)

1. An aerial work platform, comprising:

   - a chassis (1) mounted on wheels (4, 5) for movement of the aerial work platform on the ground;

   - a work platform (3);

   - a lifting mechanism (2) mounted on the chassis and supporting the work platform (3) for moving it in height;

   - two side bars (10) arranged under the chassis, each being able to move with respect to the chassis between:

   ∘ a raised position; and

   ∘ a lowered position in which the side bar projects beyond the chassis in the direction of the ground; and

   - an actuator (30) allocated solely to the actuation of the two side bars for moving them from the raised position to the lowered position and vice versa,

   characterised in that the actuator has two opposite ends through which it actuates the two side bars by varying the distance between the two ends, the actuator acting on each of the two side bars through another one of the two ends and the actuator being held only through the two ends.
2. The aerial work platform according to claim 1, in which:

   - each of the bars (10) is mounted on the chassis (1) through connection elements (21, 22; 21, 22, 61-65); and

   - the actuator (30) is held on the chassis solely through said connection elements.
3. The aerial work platform according to claim 1 or 2, in which the bars (10) are mounted on the chassis (1) in a pivoting connection.
4. The aerial work platform according to any of claims 1 to 3, in which the actuator (30) urges each bar (10) in the lowered position against a respective fixed stop of the chassis (1).
5. The aerial work platform according to claims 3 and 4, in which, in the lowered position, the bottom edge (10a) of each bar (10) is offset with respect to a vertical (V) passing through the pivot axis so that the forces external to the aerial work platform that are exerted vertically upwards on the bottom edge of the bar are countered by the respective fixed stop of the chassis.
6. The aerial work platform according to any of claims 1 to 5, in which the actuator (30) urges the bars (10) in the raised position against a fixed stop of the chassis.
7. The aerial work platform according to any of claims 1 to 6, in which each bar (10) is horizontal and extends between two side wheels (4, 5) substantially over the entire length separating the two side wheels.
8. The aerial work platform according to any of claims 1 to 7, in which the actuator (30) is a cylinder or a hydraulic cylinder.
9. The aerial work platform according to claim 8, in which the cylinder (30) extends horizontally and perpendicular to the longitudinal direction of the chassis (1).
10. The aerial work platform according to any of claims 1 to 9, in which the actuator (30) opposes the forces external to the aerial work platform acting on the bars (10) that tend to move them from the lowered position to the raised position.
11. The aerial work platform according to any of claims 1 to 10, in which each of the two ends of the actuator is mounted, preferably in a pivot connection, on a respective one of the two bars or on a part on which a respective one of the two bars is secured.
12. The aerial work platform according to any of claims 1 to 11, in which each of the two ends of the actuator (30) is mounted in a pivot connection on a respective support (21) to which another one of the two side bars (10) is secured, the support being mounted pivotably on the chassis (1).
13. The aerial work platform according to claim 12, in which each of the side bars (10) is secured to the respective support (21) towards one of its longitudinal ends, each of the side bars (10) further being secured towards the other of its longitudinal ends to a second respective support (21) mounted pivotably on the chassis (1).
14. The aerial work platform according to any of claims 1 to 9, in which the actuator (30) actuates each of the two side bars through a respective locking mechanism (61-65), each locking mechanism having an unlocked position and a locked position, the actuator actuating the locking mechanisms for making them pass from their unlocked position to their locked position and vice versa, the passage to the unlocked position having the effect of moving the side bars into the raised position and the passage into the locked position having the effect of moving the bars (10) into the lowered position, the locking mechanisms in the locked position countering, independently of the actuator, any force external to the aerial work platform (F_v, F_LI, F_LE) exerted on the bars (10) that tend to move them from the lowered position to the raised position.
15. The aerial work platform according to any of claims 1 to 14, which is a scissor-type aerial work platform or a vertical-mast aerial work platform.

Images