Method of extending or retracting a high aerial work platform mounted on a wheel of a pivot arm

Abstract

The on-board electronic system of the aerial platform moves the wheels (2, 3) between the retracted and extended position by rotating the respective arms (4, 5). The method comprises the following successive steps: a) orienting each wheel tangentially to the pivoting path of the respective arm, b) moving the wheel by pivotingly actuating the respective arm, c) re-orienting the wheel so that another translation of the aerial platform is achieved. The steps are performed in different order between the wheels (2, 3) so that at any time at least one of the following conditions is met: - the braking system of at least one wheel (2, 3) is active, - at least one wheel (2, 3) is rotated by a motorized drive, - the orientation of the wheels (2, 3) prevents any translation of the aerial platform (1) on the ground due to gravity with respect to the other.

Description

Technical Field

[0001] This invention relates to the field of mobile lifting work platforms (MEWP), also commonly referred to as aerial work platforms (AWP). Background Technology

[0002] Aerial work platforms are machines designed to allow one or more people to work at heights. For this purpose, they include work platforms designed to accommodate one or more people. They are supported by a lifting mechanism that allows them to rise from a lower position on the platform's chassis to the desired working position at a higher elevation. Aerial work platforms can move on the ground, provided they are equipped with wheels or rails for this purpose. They are typically self-propelled, i.e., motorized, to allow for autonomous movement on the ground. The work platform is equipped with a control console containing control elements that allow the operator to operate the lifting mechanism and, if necessary, allow the aerial work platform to be moved on the ground.

[0003] More specifically, the present invention relates to an aerial work platform having four wheels (i.e., two front wheels and two rear wheels), which allows the aerial work platform to move on the ground and adjust its lateral spacing (commonly referred to as wheel track) to make it wider in the working position and narrower when transporting or traveling on the road.

[0004] When an aerial work platform is in the working position—that is, when the platform is raised to the desired working height by the lifting mechanism—a wide lateral wheel spacing provides greater stability. However, a wide lateral wheel spacing may be incompatible with transporting the aerial work platform on a truck or moving it on a road, as it often exceeds the maximum limits for truck transport or road travel. The fact that the lateral wheel spacing can be widened in the working position and narrowed during transport or road travel addresses both considerations. Several techniques have been proposed in the prior art to allow for variations in the lateral wheel spacing.

[0005] In the first technology, each wheel is mounted on one end of a corresponding telescopic boom, the other end of which is fixedly mounted to the chassis of the aerial work platform. The telescopic boom is driven by cylinders to laterally translate the corresponding wheels relative to the chassis of the aerial work platform, thereby changing their lateral spacing.

[0006] The limitation of the first technology is that the distance between the front and rear wheels (usually called wheelbase) is restricted by the chassis dimensions. Furthermore, changing the wheelbase is cumbersome because a special cylinder must be used to lift the aerial work platform off the ground before the wheels can be removed. Additionally, on soft ground or with a thin floor covering, the ground support pad at the cylinder end will sink into the ground under the weight of the aerial work platform.

[0007] In the second technology, technically termed "X-axis," each wheel is mounted at one end of a corresponding boom, with the opposite end of the boom pivotally mounted to the chassis about a vertical axis, thus allowing the lateral spacing of the wheels to be altered. One or more cylinders enable the boom to pivot between an extended working position and a retracted transport position. This technology is described in US 7,198,278B2, US 8,888,122 B2, and CN106080833A. Compared to the previous technology, the second technology allows for an increased wheelbase because the wheel support boom positions the front and rear wheels at a distance from the aerial work platform's chassis, respectively, in the forward and rearward directions. Therefore, this second technology further improves the stability of the aerial work platform and thus allows for even greater lifting heights.

[0008] The difficulty with the second technique lies in the practical method of pivoting the wheel support arm to change the wheel spacing. Different approaches have been proposed.

[0009] The first method is similar to that described in the first technology: it involves lifting the wheel off the ground by a dedicated cylinder before the wheel support arm is pivoted by one or more arm drive cylinders. The first method has the same disadvantages as those already mentioned in the first technology.

[0010] One variation involves pivoting the wheel support arms without translating the aerial work platform on the ground as described above, but without pre-lifting the wheels off the ground. In other words, the aerial work platform remains stationary in the same position on the ground while the wheel support arms pivot. In this case, the wheels, which are in a substantially parallel orientation to each other, rub against the ground as the wheel support arms pivot. The disadvantages of this are that it puts significant pressure on the tire rubber, accelerating tire wear, and, if the ground is soft, risk damaging the surface or creating trenches. Furthermore, the drive cylinder(s) of the wheel support arms(s) must be more powerful.

[0011] Another way to perform wheel support arm pivoting is to do so during the aerial work platform's translational movement on the ground. Compared to the former, this limits the stress on the tires and the ground, but does not eliminate it. It has also been proposed to orient the front and rear wheels, depending on the situation, to create a convergent or dispersed tilting motion to generate a force on the wheels that causes the wheel support arm to pivot in the desired direction. As a result, according to US 7,198,278 B2, the drive cylinder(s) for the wheel support arm may be less powerful or even omitted; however, the stress on the tires and the ground increases. In any case, this method assumes sufficient space to move the aerial work platform on the ground beyond the distance required to pivot the wheel support arm, which may not always be the case. For obvious safety reasons, it also requires the aerial work platform operator to be vigilant about personnel in the area where the aerial work platform may be moving on the ground.

[0012] Given these drawbacks, there is a need to improve the way wheel-supported booms pivot. An early document, FR 1 113 811, which has been neglected in practice in the aerial work platform field, contains teachings on how to achieve wheel-supported boom pivoting. This document relates to a rolling chassis with variable gauge for various vehicles on roads, land, and rail. Specifically, it discloses a rolling chassis similar to the second technology described above, where four wheels or the like are mounted at one end of the respective boom, and their opposite ends are pivotally mounted to the chassis, allowing for changes in the lateral spacing of the wheels.

[0013] Regarding how to pivot the wheel support arms, among other possibilities, it is recommended to do the following: with the rolling chassis stationary, position the wheels tangentially to the pivot circle of the wheel support arms, and then pivot all four wheel support arms simultaneously by manipulating the wheels or, alternatively, by manually or mechanically driving the wheel support arms. Once the new wheel spacing is achieved, the wheel orientation will be changed again to restore parallelism between them, allowing the rolling chassis to move on the ground under normal conditions.

[0014] This method avoids the need for the chassis to translate on the ground during wheel support arm pivoting, thus avoiding the associated drawbacks and excessive stress on the tire rubber and ground due to the tangential orientation of the wheel during wheel support arm pivoting.

[0015] However, the aforementioned extension method requires operator intervention at different stages of wheel extension. Furthermore, a drawback of this approach is that during wheel extension or retraction, if the chassis is placed on inclined ground, there is a risk of the chassis shifting horizontally under gravity, which is undesirable. In fact, there may be certain stages of wheel extension or retraction during which the wheels can freely rotate in orientations compatible with the translation of the aerial work platform on the ground. Summary of the Invention

[0016] According to one aspect, the object of the present invention is to provide a method for so-called X-axis technology, which is intended to be implemented by onboard electronics of an aerial work platform, and to at least partially mitigate the aforementioned drawbacks. In particular, an object of the method of the present invention is to avoid any risk of the aerial work platform accidentally translating on the ground under gravity during its operation.

[0017] To this end, the present invention proposes a method implemented by onboard electronic equipment of an aerial work platform for moving a pair of front wheels and a pair of rear wheels of the aerial work platform between an initial position and an end position, one of which corresponds to a retracted position and the other to an extended position. The aerial work platform is positioned on the ground by means of the wheels. The spacing between the pair of front wheels and the spacing between the pair of rear wheels are greater in the extended position than in the retracted position. The aerial work platform includes a chassis and four arms, each arm supporting a corresponding wheel. Each wheel is mounted on a first end of a corresponding arm, and a second distal end of the arm is pivotally mounted on the chassis to move the wheel between the retracted and extended positions along the pivoting path of the arm. Each wheel has a ground rolling direction, which can be changed by controlled changes in the orientation of the wheel relative to the corresponding arm. The method includes the following sequential steps for each wheel:

[0018] a. Change the position of the wheel relative to the corresponding arm to obtain an orientation tangent to the pivot path of the corresponding arm.

[0019] b. The wheel is moved from the initial position to the final position by pivoting the corresponding arm, wherein the available braking system for the wheel is not activated during the movement, and the wheel remains tangentially oriented to the pivoting path of the arm during the movement, and optionally,

[0020] c. Control the change in the orientation of the wheels relative to the corresponding boom, so that after performing step c) on all wheels, the wheels have a rolling direction corresponding to the common direction of travel of the aerial work platform on the ground.

[0021] The execution of steps a), b), and, if applicable, c) for all wheels is asynchronous, such that for all wheels, at any time from the start of step a) to the end of step b) or, if applicable, step c), at least one of the following conditions is satisfied:

[0022] - The braking system of at least one wheel is operational.

[0023] - At least one wheel is driven by motor rotation.

[0024] - The relative orientation of the wheels to each other prevents any translation of the aerial work platform on the ground under the influence of gravity. Of course, it should be understood that this last condition is evaluated with respect to the inclination angle of the ground on which the aerial work platform is located, which is less than or equal to the maximum permissible inclination angle for performing the extension or retraction of the wheels.

[0025] Due to the non-synchronization as defined, when the aerial work platform is located on inclined ground, the risk of accidental translation of the aerial work platform under gravity during the execution of this method is eliminated, at least provided that the ground inclination angle does not exceed the maximum permissible inclination angle for using the aerial work platform. For simplicity, the booms supporting the wheels are preferably made as rigid single pieces.

[0026] According to a preferred embodiment, the present invention includes one or more of the following features:

[0027] - The execution of steps a), b), and, if applicable, c) for all wheels (2, 3) is asynchronous, such that for all wheels, at any time from the start of step a) until the end of step b) or, if applicable, step c), at least one of the following conditions is satisfied:

[0028] • The braking system is active on at least two wheels.

[0029] • At least two wheels are driven by motor rotation.

[0030] • The relative orientation of the wheels to each other prevents the aerial work platform from translating on the ground under the influence of gravity;

[0031] - Before executing step b) on any of the other wheels, initiate step a) on each wheel.

[0032] - Performing step b) for each wheel overlaps at least partially in time with performing step b) for the other wheels;

[0033] - Synchronization start step b) for the first pair of wheels, and synchronization start step b) for the second pair of wheels, the second pair of wheels is formed by wheels other than the two wheels that form the first pair of wheels, and the second pair of wheels is started in step b) with time offset relative to the first pair of wheels.

[0034] - Perform step b synchronously on the first pair of wheels, and perform step b synchronously on the second pair of wheels.

[0035] - The pivoting actuation of the arm during step b) is performed by means of an actuator specifically designed for actuating one or more arms and / or by the motorized rotation of a wheel corresponding to the arm;

[0036] - Actuation of at least one of the wheels in step b) of the central pivot arm includes or comprises a motor rotation drive of the wheel;

[0037] - For the wheel, the change in the ground rolling direction relative to the corresponding arm is achieved by pivoting the wheel relative to the pivot axis, which is offset relative to the wheel's midplane perpendicular to the wheel's axis of rotation, and the change in the wheel's orientation relative to the corresponding arm in step a) and / or step b) is obtained or assisted by the wheel's motor rotation drive.

[0038] - This method is executed by the onboard electronic equipment when the operator initiates at least one control, wherein, as long as the initiation of the control is maintained by the operator, the execution of the method continues by the onboard electronic equipment until the wheels reach the end position corresponding to the limit retracted position or the limit extended position, and if the control is released by the operator before the limit retracted position or the limit extended position of the wheels has been reached, the execution of the method is interrupted by the onboard electronic equipment; in the latter case, if the wheels are not all in the limit extended position, the onboard electronic equipment can also prevent the lifting of the aerial work platform; preferably, in the latter case, if the execution of the method is interrupted by the onboard electronic equipment due to the operator releasing the control, and the wheels are not all in the limit extended position, the onboard electronic equipment activates a signal to notify the operator that the lifting of the work platform is prevented;

[0039] - This method is executed by the onboard electronic equipment when the operator initiates at least one control, wherein, as long as the initiation of the control is maintained by the operator, the execution of the method continues by the onboard electronic equipment until the wheels reach the end position corresponding to the limit retracted position or the limit extended position, and if, during the execution of step b) for each wheel, the control is released by the operator before the wheel has reached the limit retracted position or the limit extended position, the onboard electronic equipment continues to execute the method until the wheels reach the end position after the change between the limit retracted position and the limit extended position; preferably, if the onboard electronic equipment continues to execute the method until the wheels reach the end position after the change between the limit retracted position and the limit extended position, the onboard electronic equipment further prevents the lifting of the aerial work platform or limits the operator's maximum height that the work platform can be raised with respect to the condition that all wheels are in the limit extended position.

[0040] This invention also proposes an aerial work platform, comprising:

[0041] - Chassis,

[0042] -Work platform,

[0043] - A lifting structure that is mounted on the chassis and supports the work platform to raise it to a certain height.

[0044] - A pair of front wheels and a pair of rear wheels that can move between a retracted position and an extended position. The aerial work platform is positioned on the ground by means of the wheels. The distance between the pair of front wheels and the distance between the pair of rear wheels are greater in the extended position than in the retracted position.

[0045] -In-vehicle electronic equipment,

[0046] - Four arms, each arm supporting a corresponding wheel. Each wheel is mounted on the first end of the corresponding arm, and the second distal end of the arm is pivotally mounted to the chassis to move the wheel between a retracted position and an extended position along the pivoting path of the arm. Each wheel has a ground rolling direction, which can be changed by altering the orientation of the wheel relative to the corresponding arm. Onboard electronics are configured to control the changes in the orientation of the wheel relative to the corresponding arm.

[0047] - A braking system for at least two of the wheels, configured to be controlled by onboard electronic equipment.

[0048] In this embodiment, for each wheel, if the wheel is driven, the motor rotation drive of the wheel can be controlled by onboard electronic equipment, and / or the associated boom can be actuated by the actuator of the aerial work platform to pivot, and wherein the onboard electronic equipment is configured to perform the method according to the invention.

[0049] According to a preferred embodiment, the aerial work platform further includes one or more manual control components, preferably arranged on a console mounted on the aerial work platform, and the on-board electronic equipment is configured to perform any of the preferred features of a method related to operator control and actuation of the manual control components or at least one manual control component.

[0050] In the latter case, the manual control component includes or comprises at least one switch prestressed to a rest position, more preferably including or comprising:

[0051] - At least one reversing switch, prestressed toward a neutral, neutral position, and onboard electronics arranged such that the wheels move to the extended position only when the switch is actuated in a given direction, and to the retracted position only when the switch is actuated in the opposite direction; and / or

[0052] - At least two switches, each prestressed toward the rest position, and the on-board electronics are arranged such that the wheels move toward the extended position only when one of the switches is actuated, and the wheels move toward the retracted position only when the other switches are actuated.

[0053] According to another aspect, the present invention also aims to provide an aerial work platform based on so-called "X-axis" technology, which is equipped with an actuator specifically designed for the pivoting of the wheel support arm, which is protected against impacts from possible external obstacles.

[0054] To address this, the present invention proposes an aerial work platform equipped with a pair of front wheels and a pair of rear wheels, movable between a retracted position and an extended position. The platform is positioned on the ground by the wheels, with the spacing between the front wheels and the rear wheels greater in the extended position than in the retracted position. The platform includes a chassis and four booms, each boom supporting a corresponding wheel. Each wheel is mounted on a first end of the corresponding boom, and a second distal end of the boom is pivotally mounted on the chassis to allow movement of the wheel between the retracted and extended positions. The platform also includes dedicated actuators for at least one boom, preferably for all booms, for pivoting the boom between the retracted and extended positions. These dedicated actuators retract horizontally relative to the extension of the chassis, at least when the corresponding boom is in the extended position. In this way, during translation on the ground along a direction corresponding to the side of the chassis on which the actuator is disposed, the actuators are protected from the risk of collision with potential obstacles outside the aerial work platform. In effect, the chassis absorbs the impact of potential obstacles without allowing the obstacles to come into contact with the actuators.

[0055] According to a preferred embodiment, the invention in this respect includes one or more of the following features:

[0056] - The actuator is a cylinder mounted between the chassis and the corresponding arm;

[0057] - The actuator is mounted at a point on the chassis, in the lateral direction, between the pivot axes of the two arms supporting the front wheel when the actuator is mounted to the arm supporting the front wheel, or between the pivot axes of the two arms supporting the rear wheel when the actuator is mounted to the arm supporting the rear wheel.

[0058] - Provide such actuators or cylinders for the two arms supporting the front wheels and / or for the two arms supporting the rear wheels;

[0059] - The chassis extension is located horizontally below the actuator or cylinder;

[0060] - The chassis extension is made of a material integrally with the chassis floor plate (preferably the lower chassis floor plate);

[0061] - Each wheel has a ground rolling direction, which can be changed by controlled alteration of the wheel's orientation relative to the corresponding arm. Attached Figure Description

[0062] Other aspects, features, and advantages of the invention will be presented from the following description, which uses preferred embodiments of the invention as examples and with reference to the accompanying drawings of a four-wheeled aerial work platform movable from a retracted position to an extended position (and vice versa).

[0063] [ Figure 1 This image shows a perspective view of an aerial work platform with all four wheels in the retracted position.

[0064] [ Figure 2 This shows a top view of an aerial work platform with all four wheels in the retracted position.

[0065] [ Figure 3 This image shows a perspective view of an aerial work platform with its four wheels in the extended position.

[0066] [ Figure 4 This shows a top view of an aerial work platform with its four wheels in the extended position.

[0067] [ Figure 5 This image shows a perspective view of the chassis of an aerial work platform as seen from above, with the wheels in the extended position.

[0068] [ Figure 6 This image shows a perspective view of the chassis of an aerial work platform, viewed from a point below the chassis, with the wheels in the extended position.

[0069] [ Figure 7 The image shows a perspective view of the chassis of an aerial work platform, with the wheels in a retracted position corresponding to the initial position where the wheels would move to the extended position.

[0070] [ Figure 8 This represents a top view of the chassis, with the wheels positioned within [...]. Figure 7 In the configuration of ].

[0071] [ Figure 9 [] represents a top view of the chassis, where the wheels and their support arms are in a position at a given time during the wheel extension method.

[0072] [ Figure 10 [This represents a top view of the chassis, where the wheels and their support arms are positioned later in the wheel extension method than [ ]. Figure 9 [A location at a specific time].

[0073] [ Figure 11 [This represents a top view of the chassis, where the wheels and their support arms are positioned later in the wheel extension method than [ ]. Figure 10 [A location at a specific time].

[0074] [ Figure 12[This represents a top view of the chassis, where the wheels and their support arms are positioned later in the wheel extension method than [ ]. Figure 11 [A location at a specific time].

[0075] [ Figure 13 [This represents a top view of the chassis, where the wheels and their support arms are positioned later in the wheel extension method than [ ]. Figure 12 [A location at a specific time].

[0076] [ Figure 14 [This represents a top view of the chassis, where the wheels and their support arms are positioned later in the wheel extension method than [ ]. Figure 13 [A location at a specific time].

[0077] [ Figure 15 [This represents a top view of the chassis, where the wheels and their support arms are positioned later in the wheel extension method than [ ]. Figure 14 [A location at a specific time].

[0078] [ Figure 16 [ ] represents a flowchart of a preferred embodiment of the method of the present invention.

[0079] [ Figure 17 [] indicates the control console installed on the work platform of the aerial work platform. Detailed Implementation

[0080] An implementation example of the method according to the present invention will now be described in detail with reference to aerial work platform 1, the overall view of which is as follows. Figure 1 aspect by Figure 1 and Figure 2 It is shown that, on the other hand, by Figure 3 and Figure 4 As shown. In the following description, any reference to vertical or horizontal orientation is defined with respect to the case where the aerial work platform 1 is placed on the ground forming a horizontal reference plane.

[0081] The aerial work platform 1 includes a chassis 10 and a lifting structure 20 that supports a work platform 30, which is configured to receive onboard personnel and equipment for work at height. The platform 10 typically includes a floor 32 and guardrails 34. A control console 40 is disposed on the work platform 30. It allows the operator on the work platform 30 to control the lifting structure 20 to move the work platform 30 upwards to a desired location and to move the chassis 10 on the ground.

[0082] The lifting structure 20 includes a turntable 22 mounted on a chassis 10 and a telescopic cantilever 24 pivotally mounted to the turntable 22 about a horizontal axis. The turntable 22 is pivotally mounted on the chassis 10 about a vertical axis, allowing the orientation of the lifting structure 20 to be changed, thereby changing the orientation of the work platform 30 relative to the chassis 10. To allow partial movement of the work platform 30 without acting on the cantilever 24, the lifting structure 20 also includes a swing arm 26, one end of which is hinged to the upper end of the telescopic cantilever 24, while the other end of the swing arm 26 hinged to support the work platform 30. It should be understood that the lifting structure 20 may differ from what is described. For example, it may also include a pantograph articulated arm, one end of which is mounted on the turntable 22 about a horizontal axis, and the other end of which also supports the telescopic cantilever 24 about a horizontal axis; this connecting arm is configured to extend in height. Optionally, the swing arm 26 may be omitted. The lifting structure 20 typically includes a set of actuators to generate various movements of the lifting structure 20, such as a hydraulic motor for rotating the turntable 22 and a set of hydraulic cylinders for extending the telescopic boom 24, swing arm 26 and partial displacement of the work platform 30.

[0083] The chassis 10 is equipped with two front wheels 2 and two rear wheels 3 configured to make contact with the ground: the front and rear sides of the aerial work platform 1 are indicated by arrows and are referred to as AV and AR, respectively. In use, the aerial work platform 1 rests on the ground by means of the wheels 2 and 3, which allows the aerial work platform to move horizontally on the ground.

[0084] Wheels 2 and 3 are each supported by a corresponding arm, referring to arm 4 for each front wheel 2 and arm 5 for each rear wheel 3. More specifically, each of wheels 2 and 3 is mounted at one end of a corresponding arm 4 or arm 5, while a second distal end of the arm is pivotally mounted to the chassis 10. Figure 5 and Figure 6 As shown, arms 4 and 5 preferably have the same length and are arranged symmetrically with respect to the longitudinal vertical mid-plane L of the aerial work platform 1. In the top view, the normal forward and backward translational directions of the aerial work platform 1 overlap with plane L. Optionally, arm 5 may have a different length than arm 4.

[0085] The pivoting of each arm 4, 5 relative to the chassis 10 allows the corresponding wheel 2 or 3 to... Figure 1 and Figure 2 The retraction position shown and Figure 3 and Figure 4 The wheels move between the extended and retracted positions. For this purpose, the respective pivot axes 14, 15 of each arm 4, 5 are vertical relative to the chassis 10, or at least have an angle of inclination with respect to the vertical component, so that the corresponding wheels can move between the retracted and extended positions.

[0086] like Figure 2 and Figure 4 As shown, the horizontal distance “D” between the rear wheels 3 in the extended position is greater than the horizontal distance “d” between the rear wheels in the retracted position. The same applies to the horizontal distance between the front wheels 2 (not shown in the figure). In both the retracted and extended positions, the horizontal distance between the front wheels 2 is preferably the same as the horizontal distance “d” or “D” between the rear wheels 3. However, alternatively, this distance can be different.

[0087] In the retracted position of wheels 2 and 3, their spacing "d" is preferably less than or equal to 2.5 m, which makes the aerial work platform 1 suitable for travel on roads of standard width or for loading onto trailers used for transport on such roads. The retracted position of wheels 2 and 3 thus corresponds to the transport or road travel configuration of the aerial work platform 1.

[0088] Conversely, the extended position of wheels 2 and 3 is the working configuration of the aerial work platform 1 for raising the lifting structure 20 to position the work platform 30 at the desired working height. In this position, the distance "D" between wheels 2 and between wheels 3 is preferably greater than 3m, or even greater than or equal to 4m, or even up to 5m. In the extended position, the wheelbase, i.e., the distance between the front wheels 2 and the rear wheels 3, is preferably substantially equal to the distance 'D'. The relative positioning of wheels 2 and 3 in the extended position provides the aerial work platform 1 with greater stability than in the retracted position. This allows the aerial work platform 1 to lift the work platform 30 to a great height, for example, over 40m, which is impossible in the retracted transport position.

[0089] The retracted and extended positions of arms 4 and 5 preferably correspond to the extreme pivot positions, where wheels 2 and 3 are closest to each other in the former (retracted position) and furthest from each other in the latter (extended position). However, the aerial work platform 1 can also be configured to be used with wheels 2 and 3 only partially extended, i.e., arms 4 and 5 are then positioned in an intermediate pivot position between the two extreme pivot positions.

[0090] Arm actuators are used to pivot each arm 4, 5 between the retracted and extended positions. In this case, as... Figure 5 and Figure 6As shown, each arm 4, 5 can be actuated by a corresponding cylinder 18, 19 disposed between the chassis 10 and the corresponding arm. Alternatively, it is conceivable to use a common actuator for both arms, such as a common cylinder for the front arm 4 and another common cylinder for the rear arm 5. In the latter case, the cylinders can be mounted between the two corresponding arms at their respective ends. Optionally, one end of the cylinder can be mounted on the chassis 10, and its opposite end can be mounted to a hinge mechanism connecting the two corresponding arms, such that the cylinder actuates the two arms to pivot via the hinge mechanism. In another variation, the pivoting actuation of arms 4, 5 can also be achieved by the rotational drive of the corresponding wheels, as we will see later, when the wheels are driven. In this case, a dedicated actuator (i.e., in this example, the corresponding cylinder 18 or 19) can cooperate with the rotational drive of the wheels, or it can be omitted. These different variations can be combined: for example, the actuation technology of the first pair of arms may be different compared to the second pair of arms.

[0091] Preferably, while the aerial work platform 1 is moving on the ground, cylinders 18 and 19 are protected from potential impacts from external obstacles. Figure 5 and Figure 6 As shown, this protection can be achieved through the front extension 10a and the rear extension 10b of the chassis 10, with cylinders 18 and 19 retracting in the forward and rearward directions respectively relative to these extensions, regardless of the angular position of the corresponding arms 4 or 5 between the retracted and extended positions. Therefore, the chassis 10 will absorb impacts from potential obstacles without allowing the obstacles to come into contact with cylinders 18 or 19. Preferably, the front extension 10a and the rear extension 10b are located at a horizontal height below cylinders 18 and 19, respectively, and extend substantially at the same horizontal height as cylinders 18 and 19 to effectively protect cylinders 18 and 19 from obstacles on the ground. Figure 5 and Figure 6 As shown, the extensions 10a and 10b can be integrally made of the same material as the base plate of the chassis 10, particularly the lower base plate of the chassis 10.

[0092] A locking system is provided for each of arms 4 and 5 to selectively prevent pivoting relative to chassis 10 in extreme pivot positions (i.e., in the retracted and extended positions, or even in intermediate pivot positions). One way to ensure locking is to prevent pivoting of arm 4 or 5 by hydraulic locking of the corresponding cylinder 18 or 19, for example by selectively blocking hydraulic fluid in the two chambers of the corresponding cylinder 18 or 19, which is implemented as a double-acting hydraulic cylinder, by setting two controlled valves associated with the cylinder. This method is easy to implement and allows locking of arms 4, 5 in any intermediate pivot position.

[0093] Other locking systems are also possible. For example, a locking system may include permanently actuating a corresponding cylinder 18 or 19 in the retracted and extended positions to continuously push the arm 4 or 5 against a dedicated stop on the chassis 10. According to another example, dedicated electromechanical or hydraulic devices, such as those directly mounted on the pivot axes 14, 15, may be provided to mechanically or selectively fix the arm 4 relative to the chassis 10 in a desired pivot position to prevent rotation of the arm or pin mechanism attached to one, in order to selectively engage a dedicated opening associated with the other.

[0094] The aerial work platform 1 is motorized to allow it to move automatically on the ground. In this case, each wheel 2, 3 is motorized. Although they may differ, it is preferred that an electric or hydraulic motor (not shown) is integrated in each drive wheel 2 and / or 3, which avoids complex motion transmission chains from the chassis 10 if the motor(s) are mounted on the chassis 10 or the corresponding boom 4 or 5. Optionally, only the front wheels 2 are driven, or conversely, only the rear wheels 3 are driven.

[0095] Each wheel 2, 3 is equipped with a braking system (not shown), which can be of any suitable known type, such as a hydraulic or solenoid braking system. Optionally, only some wheels may be equipped with such a system, for example, a pair of front wheels 2 or a pair of rear wheels 3. In this case, in the subsequent description of the extension method of wheels 2, 3, reference to the active or inactive state of the braking system will be ignored for the relevant wheels. Then, if necessary, the active state of the braking system can be replaced by placing at least two wheels in mutually different orientations, thereby providing the same effect of properly holding the aerial work platform 1 on the ground.

[0096] Each wheel 2, 3 is oriented. For this purpose, each front wheel 2 is pivotally mounted to its corresponding arm 4 about a vertical axis 16 or at least an axis with a vertical component tilt angle. The same applies to the rear wheels 3 relative to their respective arms 5: see reference pivot axis 17. Changes in the rolling direction of each wheel 2, 3 on the ground, i.e., changes in their orientation relative to their respective arms 4 or 5, are ensured by a corresponding steering actuator, in this case, a cylinder mounted between the arm and the associated wheel. This can be a hydraulic cylinder or an electric cylinder. Other actuation techniques are also possible.

[0097] The aerial work platform 1 includes onboard electronic equipment for controlling the motorization of drive wheels 2 and / or 3, actuators for boom 4 and / or 5, locking system for boom 4 and 5 pivoting, steering actuators for wheels 2 and 3, and braking system for wheels 2 and / or 3.

[0098] Furthermore, the aerial work platform 1 includes sensors known per se for indicative to the onboard electronic equipment of the angular orientation of the wheels 2, 3 relative to the corresponding booms 4, 5, and the pivoting position of the booms 4, 5 relative to the chassis 10. As a non-limiting example, it could be one of the following sensor technologies:

[0099] - The cylinder rod extension is linearly measured by a Hall effect sensor or magnetostrictive sensor placed in the relevant cylinder.

[0100] - The angle of pivoting or turning pivot of the arm is measured by a Hall effect sensor positioned on the relevant pivot.

[0101] - For example, on / off measurements can be performed at the extreme pivot positions of arms 4 and 5 using mechanical sensors or ILS sensors.

[0102] We will now refer to [ Figure 16 The flowchart in [ ] describes the method of moving wheels 2 and 3 from their retracted position to their extended position. It should be understood that the flowchart only indicates the beginning of the method steps that are related to each other, and does not indicate the end of the steps that are related to each other.

[0103] The retracted and extended positions of wheels 2 and 3 correspond to the extreme pivot positions of arms 4 and 5, but they can also be intermediate pivot positions. Figures 8 to 15 The configuration of the chassis 10, arms 4 and 5, and wheels 2 and 3 is shown at different steps of the method. After the operator activates the corresponding command, it is automatically executed by the onboard electronic equipment of the aerial work platform 1. It should be understood that all actions of the method described below are controlled by the onboard electronic equipment, even if not explicitly stated otherwise.

[0104] This method from Figure 7 and Figure 8 The initial configuration of the aerial work platform 1 shown is executed. It is done through [ Figure 16 The flowchart is confirmed by block 100, corresponding to time t0 on the time axis. In this configuration, the aerial work platform 1 is fixed and in a transport configuration. In other words, the braking systems of wheels 2 and / or 3 are activated and wheels 2 and 3 are in the retracted position. The locking system for boom pivoting is activated. Wheels 2 and 3 are oriented parallel to each other along the longitudinal axis L of the aerial work platform 1. In other words, wheels 2 and 3 have a common rolling direction that allows the aerial work platform 1 to translate linearly on the ground in a forward AV or backward AR direction.

[0105] If wheels 2 and 3 have different initial orientations, the method may include a preceding step in which onboard electronics control the steering actuators of the relevant wheels 2 and / or 3 to orient them as described above. Alternatively, subsequent steps may also be performed directly from either orientation of wheels 2 and / or 3.

[0106] We will first describe the steps related to the extension of the rear wheel 3.

[0107] In the first step 110, starting at time t1, the onboard electronic equipment controls the steering actuators of the rear wheels 3 to adopt an orientation tangent to the pivoting paths T5, T5' of the corresponding arms 5 around their pivot axis 15. In other words, the rolling direction of each wheel 3 is tangent to the pivoting paths T5, T5' of the corresponding arms 5. Figure 9 This situation is illustrated in the diagram, where the rear wheel 3 pivots about the pivot axis 17 in the following direction. Figure 8 The dashed bow-shaped arrow is used to represent this.

[0108] If, as illustrated in the example, the pivot axis 17 of wheel 3 is offset by a non-zero distance “e” relative to the center plane P of the rear wheel 3, and this center plane P is perpendicular to its axis of rotation R (see […]), then… Figure 8 If the braking system of the rear wheel 3 is to be deactivated throughout the first step, this prevents the tire tread of wheel 3 from rubbing against the ground and from digging trenches if the ground is soft.

[0109] Furthermore, during the first step, the motor rotation drive of wheel 3 is activated to assist in changing the direction of the wheel operated by the steering actuator of wheel 3. This allows for a smaller size for the latter.

[0110] Alternatively, the wheel steering actuator 3 can be configured to independently ensure the orientation change of the rear wheel 3. In this case, during the orientation change operation, the wheel 3 remains free to rotate and roll freely on the ground. This avoids the need to synchronize the motor rotation drive of the wheel 3 with the action of the wheel steering actuator.

[0111] Optionally, the pivot paths T5 and T5' of the rear wheel 3 relative to the corresponding arm 5 can be tangentially driven solely by the motorized rotation of the rear wheel 3, i.e., without the active participation of the steering actuator of the wheel 3. This also avoids the need to synchronize the rotational drive of the wheel 3 with the action of the steering actuator of the wheel 3.

[0112] Contrary to the example shown, if the pivot axis 15 is contained in the intermediate plane P and intersects the rotation axis R of the wheel 15, the first step is performed solely by the wheel steering actuator 3; that is, no motor rotation drive of the wheel 3 is required. Furthermore, in this case, disabling the braking system of the wheel 3 is unnecessary.

[0113] Once the first step 110 is completed, in other words, when wheel 3 is placed in a tangential position relative to the pivoting paths T5, T5' of the corresponding arm 5 (e.g. Figure 9 As shown), the vehicle's electronic equipment is activated (see time t2) in the second step 120, which includes pivoting the arm 5 to bring the wheel 3 into the extended position.

[0114] To achieve this, the onboard electronics deactivate the locking system for pivoting arm 5 and pivot arm 5 to a position corresponding to the extended position of wheel 3. This position is achieved through […]. Figure 12 As shown. During the second step 120, the braking system of wheel 3 is deactivated, and throughout the second step 120, the tangential orientation of wheel 3 relative to the pivot paths T5, T5' of the corresponding arm 5 is maintained.

[0115] The pivoting of arm 5 can be caused solely by the actuator of arm 5 (i.e., in this case, cylinder 19). In this case, wheels 3 remain free to rotate during the duration of the second step 120, which allows them to roll on the ground during the pivoting of arm 5.

[0116] Conversely, the pivoting of arm 5 can be caused solely by the motorized rotation of wheel 3, causing it to roll on the ground. The motorized rotation of wheel 3, relative to the tangential orientation of the pivoting paths T5, T5' of the corresponding arm 5, causes arm 5 to pivot. In this variant, the dedicated actuator for arm 5 (i.e., in this case, cylinder 19) can be omitted.

[0117] Preferably, the pivoting of arm 5 is caused by a combination of the actuator of arm 5 (i.e., in this case, cylinder 19) and the motorized rotation drive of wheel 3. This has the advantage of limiting the power required for the motorization of the actuator of arm 5 and the drive of wheel 3.

[0118] Of the three ways arm 5 pivots, there is almost no friction between the tire tread of wheel 3 and the ground, and the risk of digging a ditch on soft ground is almost zero.

[0119] At the end of the second step 120, when the arm 5 has reached the pivot position corresponding to the extended position of the wheel 3, the locking system for pivoting the arm 5 is activated.

[0120] Following the second step 120, the onboard electronic equipment initiates the third step 130 (see time t3), which involves again changing the orientation of the rear wheels 3 to adopt a rolling direction on the ground corresponding to the translational direction of the aerial work platform 1. Preferably, the rear wheels 3 return to a position parallel to each other along the longitudinal axis L of the aerial work platform 1, as in the initial step 100. In other words, the rear wheels 3 again have a common rolling direction, allowing the aerial work platform 1 to translate linearly on the ground in a forward AV or backward AR direction. This situation is caused by […]. Figure 13 ] shows, [ Figure 13 This corresponds to the time when the rear wheel 3 has reached the new position.

[0121] The actuation of the orientation change of the rear wheel 3 during the third step 130 is performed in any manner described in the orientation change of the rear wheel 3 during the first step 100.

[0122] At the end of the third step 130, the braking system of the rear wheel 3 is activated again.

[0123] Steps 110, 120, and 130 pertain to the extension of the rear wheel 3. The extension of the front wheel 2 is performed in the same manner as the rear wheel 3. In other words, the same steps 110, 120, and 130 are applied to the front wheel 2 with the necessary modifications, as referenced accordingly. Figure 16 The flowchart shows steps 110', 120', and 130'. The only difference is that steps 110', 130', and 120' are executed in a time-shifted manner relative to steps 110, 130, and 130. As can be seen from the flowchart, the first step 110' for the front wheel 2 starts at time t1' later than the start time t1 of the first step 100 for the rear wheel 3. Therefore, the second and third steps 120' and 130' related to the front wheel also start at times t2' and t3' after the start times t2 and t3 of the start steps 120 and 130 for the rear wheel 3, respectively, while assuming that the execution speed of each step is preferably substantially the same as that of the front wheel 2 and the rear wheel 3. However, the execution speed can be different.

[0124] [ Figure 10 The symbol ] indicates the position of arm 5 and rear wheel 3 during the second step 120, at time t1' at the beginning of the first step 110' (i.e., at the beginning when the orientation of the front wheels 2 changes so that they are tangentially oriented to the pivot path of the corresponding arm 4). In this case, time t1' is between times t2 and t3, but it can be different, for example, between times t1 and t2.

[0125] [ Figure 11 [] indicates the time during the second step 120 when the current wheel 2 reaches the tangential position relative to the pivot path of the corresponding arm 4 at the end of step 110', and the position of the arm 5 and the rear wheel 3.

[0126] [ Figure 12 [] indicates the position of arm 4 and front wheel 2 at time t3 when step 130 of the rear wheel 3 is reoriented during the second step 120'.

[0127] [ Figure 13 [] indicates the time t3 during the second step 120', after the wheel 3 completes reorientation during step 130, and the position of the arm 4 and the front wheel 2.

[0128] [ Figure 14[] indicates the position of arm 4 and front wheel 2 at time t3' when the reorientation of front wheel 2 begins in the third step 130', while rear wheel 3 has already been reoriented in step 130.

[0129] [ Figure 15 This indicates that arms 4 and 5 and wheels 2 and 3 are in their final configuration after steps 130 and 130', that is, wheels 2 and 3 are in the extended and reoriented position, which corresponds to [ Figure 16 Box 140 in the flowchart.

[0130] The advantage of making the extension of the front wheels 2 asynchronous with that of the rear wheels 3 is that if the aerial work platform 1 is placed on an inclined surface, the risk of it shifting under gravity is eliminated. In fact, if the extension of all four wheels 3 and 4 is synchronized, there will be a period during the extension operation when the front wheels 2 and the rear wheels 3 rotate freely at the same time in substantially the same or sufficiently close orientations, which would create a risk of the aerial work platform 1 shifting.

[0131] Although a motorized rotary drive is used to drive wheels 3 and 4 in all steps 110, 120, and 130, as well as 110', 120', and 130', this risk still exists if performed synchronously. In fact, the transition between steps 110 and 120 requires reversing the rotation direction of the rear wheel 3, and the corresponding steps for the front wheel 2. This reversal of rotation direction means that for several seconds, wheels 2 and 3 are free to rotate before being effectively driven to rotate in the other direction. However, as separately in... Figure 9 and Figure 11 As shown, this occurs when arms 5 and 4 are still retracted and the rear wheel 3 and front wheel 2 are oriented tangentially to the pivot path of the corresponding arm 4 or 5. As a result, wheels 2 and 3 have an orientation nearly perpendicular to the longitudinal axis L, or even corresponding to it according to the design of the aerial work platform 1, which allows the aerial work platform to translate under the influence of gravity if it is placed on ground inclined in that direction.

[0132] The duration of this risk situation is typically longer if the motorized rotation drive of wheels 3 and 4 is not used during steps 110, 120, and 130, as well as during steps 110', 120', and 130'. Therefore, it is preferable to use a motorized rotation drive for wheels 3 and 4 during all steps 110, 120, and 130, as well as during steps 110', 120', and 130', to limit the risk of displacement of the aerial work platform 1 under gravity from the outset.

[0133] In any case, the asynchrony of the extension of the front wheel 2 with respect to the extension of the rear wheel 3 can be achieved in such a way that the risk of displacement of the aerial work platform 1 under gravity, as just explained, is eliminated. In fact, asynchrony can be achieved in such a way that at any time during the extension operation, at least one of the following conditions is met:

[0134] - The braking system of at least one wheel 2 or 3, more preferably two wheels, is operational.

[0135] - At least one wheel 2, 3, more preferably two wheels are driven by motor rotation.

[0136] - The wheels 2 and 3 are positioned as far apart as possible relative to each other (i.e., their rolling directions) to prevent the aerial work platform 1 from translating on the ground under the influence of gravity on the inclined ground.

[0137] When the aerial work platform 1 is located on an inclined ground, each of these conditions is sufficient in itself to eliminate the risk of the aerial work platform 1 shifting on the ground under the action of gravity.

[0138] Based on the structural design of the chassis 10 and arms 4, 5, if the aerial work platform 1 is placed on an inclined surface and the wheels 2, 3 are oriented tangentially to the pivoting paths of the corresponding arms 4, 5, there is a risk that the aerial work platform 1 may pivot under gravity: in our example, this corresponds to the portion of steps 120 and 120' performed during the time overlap. Although the pivoting paths of arms 4, 5 are not completely overlapping, this risk may exist when their pivot axes 14, 15 are relatively close to each other compared to the lengths of arms 4, 5. This risk can then be eliminated by subjecting at least one of the wheels 2, 3 to motorized rotation for at least the time during which all wheels 2, 3 are simultaneously tangential to the pivoting paths of the corresponding arms 4, 5. Another way to eliminate this risk is to ensure that all wheels 2, 3 are not simultaneously oriented tangentially to the pivoting paths of the corresponding arms 4, 5; however, this increases the duration of the extension operation of wheels 2, 3.

[0139] Conversely, performing this method moves wheels 2 and 3 from their extended position to their retracted position. The asynchronous movement of the front wheel 2 relative to the rear wheel 3 provides the same advantages as the extension described above.

[0140] The method can have several variations. For example, the steps of the method can be reversed in that the extension of the front wheels 2 is initiated before the extension of the rear wheels 3. If it is not desired to move the aerial work platform 1 when the wheels 2 and 3 have already been extended to the working position, the third steps 130 and 130' can also be omitted. In this case, the braking system of wheels 2 and / or 3 is activated at the end of steps 120 and 120'.

[0141] Alternatively, the movement of wheels 2 and 3 between the retracted and extended positions can be operated by synchronizing the first pair of wheels with each other and synchronizing the second pair of wheels with each other (unlike synchronizing the front wheels 2 and rear wheels 3 separately). For example, the first pair of wheels may include the left wheels 2 and 3, while the wheels of the second pair of wheels may include the right wheels 2 and 3. Alternatively, the first pair of wheels may include the left front wheel and the right rear wheel, and the second pair of wheels may include the right front wheel and the left rear wheel. Of course, the movement of the first pair of wheels relative to the second pair of wheels is asynchronous to achieve the aforementioned advantages.

[0142] It is advantageous to synchronize the movement of the first pair of wheels and the movement of the second pair of wheels, as this has been found to limit the movement caused at the work platform 30 by extending or retracting the wheels 2 and 3, thus reducing operator discomfort on the work platform 30. However, this method can also be achieved by desynchronizing the movement of all the wheels 2 and 3 between them.

[0143] For the same reason as limiting movement caused at the 30 points of the work platform, it has been found that it is preferable to initiate the extension or retraction of the second pair of wheels during the extension or retraction operation of the first pair of wheels. This has the additional advantage of reducing the time required to deploy wheels 2 and 3 compared to initiating the extension or retraction of the second pair of wheels after the extension step of the first pair of wheels is completed. It is also preferable that the pair of front wheels 2 and the pair of rear wheels 3 are synchronized with each other.

[0144] [ Figure 17 The image shows a control console 200 of an aerial work platform 1 mounted on a work platform 30. It typically includes control components that allow the operator to raise the work platform 30 to the air and move the aerial work platform 1 on the ground.

[0145] It also includes a control element 210 that allows the operator to initiate the extension or retraction of wheels 2 and 3. In this case, the control element 210 is a reversing switch with a lever-type intermediate position. By pushing it upwards, the onboard electronics extend wheels 2 and 3 as long as the operator lifts them. If the operator releases the lever, it returns to the neutral center position, in which case the onboard electronics stop the extension operation of wheels 2 and 3 and resume operation when the operator pushes the lever upwards again. The operation is the same when the operator pushes the lever downwards to move wheels 2 and 3 to the retracted position. This operation provides safety compared to the automatic nature of the wheel extension or retraction operation. In fact, if the operator perceives any risk of collision between wheels 2 and 3 or arms 4 and 5 and obstacles or people, the operator only needs to release the control element 210 to stop the extension or retraction operation of wheels 2 and 4. Furthermore, since the operator must remain on the horizontal plane of the console 200 for an extended period during these operations, the operator is protected from the risk of collision with wheels 2 and 3 or arms 4 and 5. Furthermore, the onboard electronic equipment is preferably configured to prevent the aerial work platform from being raised when wheels 2 and 3 are not all in their maximum extension position. If the execution of wheel extension or retraction operations is interrupted by the onboard electronic equipment due to the operator releasing the control, and the wheels are not all in their maximum extension position, the onboard electronic equipment activates a signal to notify the operator that the raising of the work platform is prevented, for example on the display 220 mentioned below.

[0146] Markers 211 and 213 are affixed above and below the switch, respectively, indicating the extended and retracted positions of wheels 2 and 3 and arms 4 and 5. The upper mark 211 and the lower mark 213 are indicated by arrows pointing to the extension and retraction directions of wheels 2 and 3 and arms 4 and 5.

[0147] Indicator lights 212 and 214 are located at the upper mark 211 and the lower mark 213, respectively. When wheels 2 and 3 are in the extended and folded positions, respectively, indicator lights 212 and 214 remain illuminated. Therefore, the operator is informed of the current position of wheels 2 and 3.

[0148] When the operator activates the control component 210 to extend or retract the wheels 2 and 3, the on-board electronic equipment illuminates the indicators 212 and 214 respectively in a flashing manner.

[0149] The console 200 also includes a display 220. When the operator actuates the control component 210, the onboard electronic equipment displays a statement indicating that the extension or retraction of wheels 2 and 3 is in progress, as well as a graphical animation of the chassis 221 showing the progress of the extension or retraction of wheels 2 and 3 and arms 4 and 5. It also displays a progress bar 222, which increases or decreases in length as the extension or retraction of wheels 2 and 3 occurs. When the extension or retraction of wheels 2 and 3 is completed, the onboard electronic equipment displays a corresponding message on the screen 220.

[0150] When wheels 2 and 3 are in the folded position and do not actuate control component 210, the on-board electronic equipment displays information on screen 220 indicating that the work platform 30 cannot be raised.

[0151] It is understood that the control component 210 can be of different types. For example, two separate switches can be provided, one for extending wheels 2 and 3 and the other for retracting wheels 2 and 3. According to another example, the extension or retraction operation of wheels 2 and 3 can be initiated via a dedicated display on touch display screen 220.

[0152] The extension or retraction of the wheels can also be remotely initiated, for example, via wireless communication between a smartphone and the onboard electronic equipment of the aerial work platform 1. A display similar to screen 220 can be provided on the smartphone screen.

[0153] In an alternative implementation, if the operator releases the control member 210 during step 120, and before reaching the limit retracted or extended positions of wheels 2 and 3, the onboard electronics can be provided to continue the extension or retraction operation until the end position of the change in wheels 2 and 3, i.e., the intermediate position between the limit retracted and limit extended positions. If the onboard electronics continue to perform the method until the end position of the change in wheels (i.e., the intermediate position between the limit retracted and limit extended positions), the onboard electronics preferably prevent the lifting of the work platform 30 or limit the maximum height that the operator can lift the work platform 30 relative to when wheels 2 and 3 are both in the limit extended positions.

[0154] Of course, the present invention is not limited to the examples and embodiments described and depicted, but is susceptible to a variety of variations available to those skilled in the art.

Claims

1. A method implemented by onboard electronic equipment of an aerial work platform (1) for moving a pair of front wheels (2) and a pair of rear wheels (3) of the aerial work platform (1) between an initial position and an end position, one of the initial position and the end position corresponding to a retracted position and the other corresponding to an extended position, The aerial work platform is placed on the ground by wheels (2, 3), and the distance (d, D) between the pair of front wheels (2) and the distance (d, D) between the pair of rear wheels (3) are greater in the extended position than in the retracted position. The aerial work platform includes a chassis (10) and four booms (4, 5), each boom supporting a corresponding wheel (2, 3). Each wheel is mounted on a first end of a corresponding boom, and a second distal end of the boom is pivotally mounted to the chassis (10) to move the wheel between the retracted and extended positions along the boom's pivoting path (T4, T4', T5, T5'). Each of the wheels (2, 3) has a ground rolling direction, which can be changed by controlled alteration of the orientation of the wheel relative to the corresponding arm (4, 5). The method includes the following sequential steps for each wheel (2, 3): a) Change the orientation of the wheel relative to the corresponding arm to obtain an orientation tangent to the pivoting path of the corresponding arm, and b) The wheel is moved from the initial position to the final position by actuating the corresponding arm pivot, wherein the wheel's available braking system is not activated during the movement, and the wheel remains tangentially oriented to the pivot path of the arm during the movement. in, The execution of steps a) and b) for all wheels (2, 3) is asynchronous, such that for all wheels, at any time from the start of step a) to the end of step b), at least one of the following conditions is satisfied: - The braking system of at least one wheel (2, 3) is operational. -At least one wheel (2, 3) is driven by motor rotation. The relative orientation of the wheels (2, 3) with respect to each other prevents the aerial work platform (1) from translating on the ground under gravity, and in: - Start step b) synchronously for the first pair of wheels. - To synchronously initiate step b) of the second pair of wheels, the second pair of wheels is formed by wheels other than the two wheels that form the first pair of wheels; and -In the case of time offset relative to the first pair of wheels, initiate step b for the second pair of wheels).

2. The method according to claim 1, wherein, Before executing step b) on any of the other wheels, initiate step a) on each wheel.

3. The method according to claim 2, wherein, The execution of step b) for each of the wheels overlaps at least partially in time with the execution of step b) for the other wheels.

4. The method according to claim 1, wherein, The execution of steps a) and b) on all wheels (2, 3) is asynchronous, such that at any time from the start of step a) until the end of step b), at least one of the following conditions is satisfied: - The braking systems of at least two wheels (2 and 3) are operational. -At least two wheels (2, 3) are driven by motor rotation. - The relative orientation of the wheels (2, 3) with respect to each other prevents the aerial work platform (1) from any translation on the ground under the action of gravity.

5. The method according to claim 4, wherein, Before executing step b) on any of the other wheels, initiate step a) on each of the wheels.

6. The method according to claim 5, wherein, The execution of step b) for each of the wheels overlaps at least partially in time with the execution of step b) for the other wheels.

7. A method implemented by onboard electronic equipment of an aerial work platform (1) for moving a pair of front wheels (2) and a pair of rear wheels (3) of the aerial work platform (1) between an initial position and an end position, one of the initial position and the end position corresponding to a retracted position and the other corresponding to an extended position, The aerial work platform is placed on the ground by wheels (2, 3), and the distance (d, D) between the pair of front wheels (2) and the distance (d, D) between the pair of rear wheels (3) are greater in the extended position than in the retracted position. The aerial work platform includes a chassis (10) and four booms (4, 5), each boom supporting a corresponding wheel (2, 3). Each wheel is mounted on a first end of a corresponding boom, and a second distal end of the boom is pivotally mounted to the chassis (10) to move the wheel between the retracted and extended positions along the boom's pivoting path (T4, T4', T5, T5'). Each of the wheels (2, 3) has a ground rolling direction, which can be changed by controlled alteration of the orientation of the wheel relative to the corresponding arm (4, 5). The method includes the following sequential steps for each wheel (2, 3): a) Change the orientation of the wheel relative to the corresponding arm to obtain an orientation tangent to the pivoting path of the corresponding arm. b) The wheel is moved from the initial position to the final position by actuating the corresponding arm pivot, wherein the wheel's available braking system is not activated during the movement, and the wheel remains tangentially oriented to the pivot path of the arm during the movement. c) Control the change in the orientation of the wheels relative to the corresponding arms, such that after step c) is performed on all wheels, the wheels have a rolling direction corresponding to the common direction of travel of the aerial work platform on the ground. in, The execution of steps a), b), and c) on all wheels (2, 3) is asynchronous, such that for all wheels, at any time from the start of step a) to the end of step c), at least one of the following conditions is satisfied: - The braking system of at least one wheel (2, 3) is operational. -At least one wheel (2, 3) is driven by motor rotation. The relative orientation of the wheels (2, 3) with respect to each other prevents the aerial work platform (1) from translating on the ground under gravity, and in: - Start step b) synchronously for the first pair of wheels. - To synchronously initiate step b) of the second pair of wheels, the second pair of wheels is formed by wheels other than the two wheels that form the first pair of wheels; and -In the case of time offset relative to the first pair of wheels, initiate step b for the second pair of wheels).

8. The method according to claim 7, wherein, The execution of steps a), b), and c) on all wheels (2, 3) is asynchronous, such that at any time from the start of step a) until the end of step c), at least one of the following conditions is satisfied: - The braking systems of at least two wheels (2 and 3) are operational. -At least two wheels (2, 3) are driven by motor rotation. - The relative orientation of the wheels (2, 3) with respect to each other prevents the aerial work platform (1) from any translation on the ground under the action of gravity.

9. The method according to claim 7 or 8, wherein, Regarding wheels: - The change in the ground rolling direction relative to the corresponding arm is achieved by pivoting the wheel relative to a pivot axis that is offset relative to the wheel's midplane, which is perpendicular to the wheel's axis of rotation. - The change in the orientation of the wheel relative to the corresponding arm in step a) and / or step c) is achieved or assisted by the motorized rotation of the wheel.

10. The method according to any one of claims 1 to 8, wherein: - Step b) is performed synchronously on the first pair of wheels, and - Perform step b synchronously on the second pair of wheels.

11. The method according to any one of claims 1 to 8, wherein, The pivoting of the arms (4, 5) is performed in step b): - By means of an actuator specifically designed to actuate one or more arms (4, 5), and / or -By the motor rotation of the wheels (2, 3) corresponding to the arm.

12. The method according to claim 11, wherein, Actuation for pivoting the arm (4, 5) in step b) for at least one of the wheels (2, 3) includes or comprises a motor rotation drive of the wheel (2, 3) corresponding to the arm.

13. The method according to any one of claims 1 to 8, wherein, Regarding wheels: - The change in the ground rolling direction relative to the corresponding arm is achieved by pivoting the wheel relative to a pivot axis that is offset relative to the wheel's midplane, which is perpendicular to the wheel's axis of rotation. - The change in the orientation of the wheel relative to the corresponding arm in step a) is achieved or assisted by the motorized rotation of the wheel.

14. The method according to any one of claims 1 to 8, wherein the method is performed by an on-board electronic device when an operator initiates at least one control, wherein, As long as the initiation of the control is maintained by the operator, the execution of the method continues by the on-board electronic equipment until the wheels (2, 3) reach the end position corresponding to the limit retraction position or the limit extension position, and if the control is released by the operator before the limit retraction position or the limit extension position of the wheels is reached, the execution of the method is interrupted by the on-board electronic equipment.

15. The method according to claim 14, wherein, If the wheels (2, 3) are not all in the extreme extension position, the on-board electronic equipment prevents the lifting of the work platform of the aerial work platform.

16. The method according to claim 15, wherein, If the execution of the method is interrupted by the onboard electronic equipment due to the operator releasing the control, and the wheels (2, 3) are not all in the extreme extension position, the onboard electronic equipment activates a signal to notify the operator that the lifting of the work platform is prevented.

17. The method according to any one of claims 1 to 8, wherein the method is performed by the on-board electronic device when an operator initiates at least one control, wherein, As long as the initiation of the control is maintained by the operator, the execution of the method continues by the on-board electronic equipment until the wheels (2, 3) reach the end position corresponding to the limit retracted position or the limit extended position, and if, during the execution of step b) for each wheel, the control is released by the operator before the limit retracted position or the limit extended position of the wheels (2, 3) has been reached, the on-board electronic equipment continues to execute the method until the wheels (2, 3) reach the end position after the change between the limit retracted position and the limit extended position.

18. The method according to claim 17, wherein, If the onboard electronic equipment continues to perform the method until the wheels (2, 3) reach a changed end position between the extreme retracted position and the extreme extended position, the onboard electronic equipment further prevents the lifting of the aerial work platform, or limits the operator's ability to lift the work platform to its maximum height with all wheels in the extreme extended position.

19. An aerial work platform (1), comprising: - Chassis, -Work platform, - A lifting structure, which is mounted on the chassis and supports the work platform to lift it to a height. - A pair of front wheels (2) and a pair of rear wheels (3) movable between a retracted position and an extended position, the aerial work platform being placed on the ground by means of the wheels (2, 3), the distance (d, D) between the pair of front wheels (2) and the distance (d, D) between the pair of rear wheels (3) being greater in the extended position than in the retracted position. -In-vehicle electronic equipment, - Four arms (4, 5), each arm supporting a corresponding one of the wheels (2, 3), each wheel mounted at a first end of a corresponding arm, and a second distal end of the corresponding arm pivotally mounted to the chassis (10) to move the wheel between a retracted position and an extended position along a pivoting path (T4, T4', T5, T5') of the arm. Each wheel (2, 3) has a ground rolling direction that can be changed by controlled alteration of the orientation of the wheel relative to the corresponding arm (4, 5). The onboard electronics are configured to control the alteration of the orientation of the wheel relative to the corresponding arm (4, 5). - A braking system for at least two of the wheels (2, 3), the braking system being configured to be controlled by the on-board electronic equipment. Wherein, for each of the wheels (2, 3), if the wheel is driven, the motor rotation drive of the wheel is controllable by the onboard electronic equipment, and / or the associated boom can be pivoted by the actuator of the aerial work platform, and The vehicle-mounted electronic device is configured to perform the method according to any one of claims 1 to 8.

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