Winding aid cylinder

Description

FIELD OF THE INVENTION

[0001] The invention relates to a take-off aid cylinder, and more particularly to a take-off aid cylinder intended to form part of a lifting device for mobile containers. STATE OF THE ART

[0002] Some transport vehicles are equipped with lifting devices which allow them to load and unload mobile containers such as skips, crates or tanks.

[0003] The lifting device may comprise a subframe fixed to the vehicle chassis and a lifting arm articulated on the subframe. The lifting arm is provided with a hook suitable for insertion into a ring of the mobile container in order to be able to load the mobile container onto the vehicle or unload it from the vehicle.

[0004] The lifting arm is movable between a retracted configuration in which the lifting arm is folded against the subframe and an extended configuration in which the lifting arm is extended so that the hook can be inserted into the ring of a mobile container placed next to the vehicle.

[0005] The lifting arm generally comprises cylinders for controlling the extension and retraction of the lifting arm. Such cylinders are known, for example, from DE 26 16 813 A1, DE 86 20 144 U1 and FR 1 139 620 A3.

[0006] However, when the lifting arm is in the retracted configuration, these cylinders can be oriented at a very small angle relative to the arm. As a result, the force applied by the cylinders has a small lever arm relative to the lifting arm's axis of rotation. Thus, the force exerted by the cylinders must be very large to initiate the extension of the lifting arm.

[0007] The force exerted by the cylinders is all the greater as the load to be lifted by the lifting arm is high. This can be the case, for example, during a tipping operation, during which the lifting arm is controlled to tip a mobile container that is initially loaded onto the vehicle backwards.

[0008] Therefore, some lifting devices include a take-off assist cylinder. The take-off assist cylinder is activated at the beginning of the lifting arm's extension movement so as to apply an additional take-off force to the lifting arm in addition to the force exerted by the main cylinders of the lifting arm.

[0009] The take-off assist cylinder extends linearly and contacts the lift arm at the beginning of the lift arm's extension movement. The take-off assist cylinder is oriented to apply a take-off force with a large lever arm relative to the lift arm's rotational axis.

[0010] However, the movement of the lifting arm is circular while the movement of the rod of the take-off aid cylinder that is in contact with the lifting arm is linear. This generates a sliding of the take-off aid cylinder on the lifting arm at the point of contact between the cylinder and the lifting arm. The friction due to the sliding of the take-off aid cylinder on the lifting arm generates radial forces on the take-off aid cylinder. These radial forces are all the greater as the take-off force exerted by the cylinder on the lifting arm is high, i.e. the load is high. In the long run, these radial forces damage the take-off aid cylinder, and can cause oil leaks. SUMMARY OF THE INVENTION

[0011] An object of the invention is to provide a take-off assist cylinder which is less likely to be damaged.

[0012] This aim is achieved within the framework of the present invention thanks to a take-off assistance cylinder comprising: a support suitable for being fixed on a subframe of a lifting device, a body, a piston mounted so as to be movable in translation relative to the body along a translation axis, a rod connected to the piston and having an end suitable for coming into contact with a lifting arm of the lifting device, to push the lifting arm during a rotation of the lifting arm relative to the subframe, and a connecting device connecting the body to the support, the connecting device allowing an angular displacement of the body relative to the support during the rotation of the lifting arm relative to the subframe, wherein the body has an external surface having a convex portion arranged to bear against a bearing surface mounted fixed relative to the subframe when the rod pushes the lifting arm, the convex portion being able to roll on the bearing surface during angular displacement of the body relative to the support.

[0013] The proposed connecting device allows the body of the take-off aid cylinder to orient itself freely as the lifting arm moves. This prevents the end of the rod from slipping on the lifting arm, and thus reduces radial forces that could damage the take-off aid cylinder.

[0014] In addition, the fact that the convex portion rolls against the bearing surface makes it possible to obtain a simple and robust connection device, which does not require lubrication, unlike a pivot or ball joint for example.

[0015] The take-off aid cylinder may also have the following characteristics: the connecting device comprises an elastic part capable of being deformed when the body is angularly moved from a first orientation to a second orientation, so as to generate an elastic restoring force tending to bring the body back to the first orientation; the elastic part comprises a block of elastic material; the connecting device comprises several elastic parts distributed around the body; the convex portion has an ellipsoidal shape, preferably a spherical shape; the body comprises a side wall delimiting an internal cavity in which the piston is received, and a bottom fixed to the side wall, the external surface being an external surface of the bottom; the bottom has a conical portion extending from the side wall to the convex portion; the bottom is fixed to the side wall by welding;the end of the rod has an external surface having a convex portion suitable for coming into contact with the lifting arm to push the lifting arm; the convex portion is suitable for rolling on a bearing surface of the lifting arm during angular displacement of the body relative to the support; the convex portion has an ellipsoidal shape.

[0016] The invention further relates to a lifting device comprising a subframe intended to be fixed on the chassis of a vehicle, a lifting arm mounted on the subframe via a pivot connection allowing rotation of the lifting arm relative to the subframe between a retracted configuration and a deployed configuration, and a take-off assistance cylinder as defined previously for pushing the lifting arm during rotation of the lifting arm relative to the subframe towards the deployed configuration.

[0017] The lifting device may further have the following characteristics: the lifting arm comprises a connecting rod having two lateral portions, the lifting device comprising two take-off assistance cylinders, each take-off assistance cylinder having a rod having an end suitable for coming into contact with a respective lateral portion of the connecting rod, to push the lifting arm; the rotation of the lifting arm from the retracted configuration to the deployed configuration causes an angular displacement of the body from the first orientation to a second orientation, and the connecting device of the take-off assistance cylinder comprises an elastic part suitable for being deformed when the body is angularly displaced from the first orientation to the second orientation, so as to generate an elastic restoring force tending to bring the body back to the first orientation.

[0018] The invention also relates to a lifting or handling vehicle, comprising a chassis and a lifting device, the lifting device comprising: a subframe fixed to the chassis, a lifting arm mounted on the subframe via a pivot connection allowing rotation of the lifting arm relative to the subframe, and a take-off assistance cylinder comprising a support fixed to the subframe, a body, a piston mounted so as to be movable in translation relative to the body along a translation axis, a rod connected to the piston and having one end intended to come into contact with the lifting arm to push the lifting arm when the lifting arm rotates relative to the subframe, and a connecting device connecting the body to the support, the connecting device allowing angular displacement of the body relative to the support when the lifting arm rotates relative to the subframe, wherein the body has a first surface and the vehicle comprises a second surface mounted fixed relative to the subframe, one of the first surface and the second surface comprises a convex portion arranged to bear on the other of the first surface and the second surface when the rod pushes the lifting arm, the convex portion being adapted to roll on the other of the first surface and the second surface during the angular displacement of the body relative to the support. PRESENTATION OF THE DRAWINGS

[0019] Other characteristics and advantages will emerge from the following description, which is purely illustrative and not limiting and must be read in conjunction with the attached figures, among which: there Figure 1 schematically represents a vehicle comprising a lifting device in the retracted configuration, the Figure 2schematically represents the vehicle comprising the lifting device in the deployed configuration, and more particularly in the tipping configuration, the Figure 3 schematically represents the vehicle comprising the lifting device in the deployed configuration, and more particularly in the loading or unloading configuration, the Figure 4 schematically represents the lifting device comprising two take-off assistance cylinders, the Figure 5 schematically represents a take-off assistance cylinder in accordance with a possible embodiment of the invention, the Figure 6 schematically represents, in longitudinal section, the take-off assistance cylinder in the extreme retracted position, the Figure 7schematically represents, in longitudinal section, the take-off assistance cylinder, at the moment when the rod comes into contact with the lifting arm of the lifting device, when the take-off assistance cylinder passes from the extreme retracted position to the extreme extended position, the figure 8 schematically represents, in longitudinal section, the take-off assistance cylinder in the extreme deployed position, the rod being in contact with the lifting arm of the lifting device, the Figure 9 schematically represents, in longitudinal section, the take-off assistance cylinder in the extreme deployed position, the rod no longer being in contact with the lifting arm of the lifting device, the Figure 10 schematically represents, in longitudinal section, the take-off aid cylinder when the take-off aid cylinder moves from the extreme deployed position to the extreme retracted position. DETAILED DESCRIPTION OF AN EMBODIMENT

[0020] On the figures 1 to 3, the vehicle 1 shown comprises a chassis 2 and a lifting device 3 mounted on the chassis 2.

[0021] The lifting device 3 comprises a subframe 4 and a lifting arm 5 articulated on the subframe 4. The subframe 4 is fixed on the chassis 2 of the vehicle 1.

[0022] In the example illustrated on the figures 1 to 3 , the lifting arm 5 comprises a rocker 6, first cylinders 7 (or main lifting cylinders), a connecting rod 8, a jib 10 and a hook 11.

[0023] The rocker 6 is pivotally mounted on the subframe 4 by means of a first pivot connection 12.

[0024] The connecting rod 8 is pivotally mounted on the rocker 6 by means of a second pivot connection 13. Each first cylinder 7 has one end connected to the subframe 4 and another end connected to the connecting rod 8. The first cylinders 7 make it possible to control the rotation of the rocker 6 relative to the subframe 4 when the connecting rod 8 is locked in position relative to the rocker 6 (configuration illustrated in the Figure 2 ) or to control the rotation of the connecting rod 8 relative to the rocker 6 when the rocker 6 is locked to the subframe 4 (configuration illustrated on the Figure 3 ).

[0025] The jib 10 can be slidably mounted on the connecting rod 8. In this case, a second cylinder mounted inside the connecting rod 18 (not shown) makes it possible to control a translation of the jib 10 relative to the connecting rod 8.

[0026] In addition, the jib 10 can be formed in two parts, one of the parts being articulated on the other part by means of a pivot connection 14. In this case, a third jack (not shown) makes it possible to control a rotation of one of the parts relative to the other.

[0027] The hook 11 is suitable for engaging in a ring 15 of a mobile container 16 in order to be able to tilt the mobile container 15 to empty it ( Figure 2 ), or to be able to load the mobile container 16 onto the vehicle 1 or unload the mobile container 16 from the vehicle 1 ( Figure 3 ).

[0028] On the Figure 1 , the lifting device 3 is in a retracted configuration, i.e. the lifting arm 5 is folded onto the subframe 4. On the Figure 1 , the lifting arm 5 holds the mobile container 16 on the chassis 2 of the vehicle.

[0029] On the Figure 2, the lifting arm 3 is in a deployed configuration, that is to say that the lifting arm 5 is unfolded to be able to tilt the mobile container 16 towards the rear of the vehicle.

[0030] To move from the retracted configuration to the deployed configuration, the lifting arm 5 is rotated relative to the subframe 3 in a first direction of rotation (illustrated by the arrow A on the Figure 2 ).

[0031] Conversely, to move from the deployed configuration to the retracted configuration, the lifting arm 5 is rotated relative to the subframe 3 in a second direction of rotation (illustrated by arrow B on the Figure 1 ), opposite to the first direction of rotation.

[0032] Likewise, on the Figure 3, the lifting arm 3 is in a deployed configuration, but this time, only the connecting rod 8 has been rotated relative to the rocker 6 (and consequently relative to the subframe 3) in the first direction of rotation.

[0033] The lifting device 3 further comprises one or more take-off assistance cylinder(s) 17 making it possible to assist the first cylinders 7 when lifting the mobile container 16, at the start of the tilting movement.

[0034] In other words, the take-off assistance cylinder(s) 17 is (are) capable of exerting a thrust on the lifting arm 5 tending to assist the rotation of the lifting arm 5 from the retracted configuration to a deployed configuration, in the first direction of rotation.

[0035] In the example illustrated on the Figure 4 , the lifting device 3 comprises two take-off assistance cylinders 17.

[0036] Furthermore, in this example, the connecting rod 8 comprises two lateral portions 31. Each take-off assistance cylinder 17 is capable of exerting a thrust force on a respective lateral portion 31 of the connecting rod 8. On the Figure 4 , the lateral portions 31 are attachment parts making it possible to connect the ends of the first cylinders 7 to the connecting rod 8. However, the lateral portions could be formed by other parts.

[0037] As illustrated on the figures 5 to 10 , the take-off assistance cylinder 17 comprises a support 18, a body 19, a piston 20 and a rod 9 connected to the piston 20.

[0038] The support 18 is suitable for being fixed to the subframe 4 of the vehicle 1, for example by bolting.

[0039] The body 19 of the take-off assistance cylinder 17 comprises a side wall 21, a nose 22 and a bottom 23.

[0040] The side wall 21 has a cylindrical shape of revolution having an axis of revolution X. The side wall 21 delimits an internal cavity 24.

[0041] The nose 22 and the bottom 23 close the internal cavity 24 at each end of the body 19.

[0042] The nose 22 is fixed to the side wall 21, for example by screwing.

[0043] The bottom 23 is fixed to the side wall 21, for example by welding.

[0044] The base 23 has an external surface 25. The external surface 25 of the base 23 comprises a convex portion 27 which is suitable for coming into contact with a bearing surface 32 fixed relative to the subframe 4. The convex portion 27 has a curved shape.

[0045] More precisely, the external surface 25 comprises a conical portion 26 and a spherical portion 27. The spherical portion 27 extends in the extension of the conical portion 26 and forms the apex of the conical portion 26. The spherical portion 27 is capable of coming to bear on the bearing surface 32 when the take-off assistance cylinder 17 actuates the lifting arm 4. The conical portion 26 has the shape of a cone of revolution having as its axis of revolution the axis of revolution X of the side wall 21.

[0046] In the example illustrated on the figures 5 to 10 , the bearing surface 32 is a surface of the subframe 4, for example a surface of a crossmember forming part of the subframe 4.

[0047] The piston 20 is mounted to move in translation relative to the body 19 parallel to a translation axis. The translation axis is parallel to an axis of revolution X of the side wall 21.

[0048] The rod 9 has a general cylindrical shape of revolution having as its axis of revolution the axis of revolution X of the side wall 21. The rod 9 is partially received inside the internal cavity 24 of the body 19. The rod 9 has a first end 28 (or lower end) located inside the body 19 and connected to the piston 20, and a second end 29 (or upper end) located outside the body 19.

[0049] The second end 29 of the rod 9 has an external surface 30 having a convex portion 35 suitable for coming into contact with the lifting arm 5. The convex portion 35 has a curved shape.

[0050] More specifically, in the example illustrated on the figures 5 to 10 , the external surface 30 has a portion 35 of ellipsoidal shape. The portion 35 of ellipsoidal shape is suitable for coming into contact with a bearing surface 45 of a lateral portion 31 of the lifting arm 5.

[0051] The piston 20 is capable of sliding inside the internal cavity 24 parallel to the translation axis (which is parallel to the axis of revolution X).

[0052] More specifically, the piston 20 is capable of sliding inside the internal cavity 24 between a first extreme position (or retracted extreme position) illustrated in the Figure 6 , and a second extreme position (or deployed extreme position) illustrated on the figure 8 .

[0053] As can be seen on the figures 6 to 10 , the piston 20 separates the internal cavity 24 into a first chamber 33 and a second chamber 34.

[0054] The take-off assistance cylinder 17 further comprises a first conduit 36 ​​and a second conduit 37.

[0055] The first conduit 36 ​​is connected to the body 19. More precisely, the first conduit 36 ​​is in communication with the first chamber 33 via a first orifice 38 provided in the base 25. The first conduit 36 ​​is suitable for being connected to a fluid injection system (not shown) for injecting fluid into the first chamber, so as to cause a translation of the piston 20 in a first translation direction (or deployment direction), illustrated by the arrow C, parallel to the translation axis. The first direction of movement is the direction of movement of the piston 20 when the piston 20 passes from the first extreme position (or retracted extreme position) to the second extreme position (or deployed extreme position).

[0056] Likewise, the second conduit 37 is connected to the body 19. More specifically, the second conduit 37 is in communication with the second chamber 34 via a second orifice 39 provided in the side wall 21. The second conduit 37 is suitable for being connected to a fluid injection system (not shown) for injecting fluid from the second chamber, so as to cause the piston 20 to move in a second direction of movement (or retraction direction), illustrated by the arrow D, opposite to the first direction of movement, parallel to the translation axis. The second direction of movement is the direction of movement of the piston 20 when the piston 20 passes from the second extreme position (or deployed extreme position) to the first extreme position (or retracted extreme position).

[0057] The injected fluid is, for example, oil.

[0058] The take-off assistance cylinder 17 further comprises a connecting device 40 between the body 19 and the support 18. The connecting device 40 comprises a plate 41 and deformable parts 42.

[0059] The plate 41 is fixed to the side wall 21. More precisely, the plate 41 extends around the side wall 21, transversely to the translation axis of the piston 20.

[0060] The plate 41 is connected to the support 18 by means of the deformable parts 42.

[0061] In the example illustrated on the figures 5 to 10 , the connecting device 40 comprises four deformable parts 42 (only three deformable parts 42 are visible on the Figure 5 ).

[0062] In the example illustrated on the figures 5 to 10, the plate 41 has a central part 43 and radial extensions 44. More precisely, in this example, the plate 41 comprises four radial extensions 44 (only three radial extensions 44 are visible on the Figure 5 ).

[0063] Each deformable part 42 may be an elastic part. In the example illustrated in the figures 5 to 10 , each elastic part 42 is a block of elastic material. The elastic material may be rubber, a plastic material, such as an elastomer, or any other material which during normal operation of the take-off assistance cylinder 17 is capable of deforming elastically. However, it would be possible to replace the block of elastic material with another elastic part, such as a spring for example.

[0064] Each block of elastic material has a cylindrical shape of revolution.

[0065] Each elastic part 42 is fixed at one of its ends to a respective radial arm 44 of the plate 41, and at the other of its ends to the support 18, for example by means of screws.

[0066] Thus, the elastic parts 42 are arranged by being distributed around the body 19.

[0067] In the absence of external stresses from the take-off assistance cylinder 17, the elastic parts 42 maintain the body 19 in a first predefined angular orientation relative to the support 18 (orientation illustrated in the Figure 6 ).

[0068] During operation of the take-off assistance cylinder 17, the elastic parts 42 may be deformed under the effect of an external stress from the take-off assistance cylinder 17, so as to allow a tilting (i.e. an angular displacement) of the body 19 relative to the support 18 towards a second angular orientation. Due to their elasticity, when they are deformed, the elastic parts 42 generate an elastic restoring force tending to oppose such tilting.

[0069] The take-off assist cylinder 17 operates as follows.

[0070] Initially, the lifting device 3 is in the retracted configuration (configuration illustrated in the Figure 1 ). In this configuration, the lifting arm 5 is folded onto the subframe 4.

[0071] The body 19 of the take-off assistance cylinder 17 is oriented according to the first angular orientation (orientation illustrated in the Figure 6) and the piston 20 of the take-off assistance cylinder 17 is in the extreme retracted position (position illustrated in the Figure 6 ). In this position, the second end 29 of the rod 9 is not in contact with the lifting arm 5. Thus, the lifting arm 4 does not stress the rod 9 of the take-off assistance cylinder 17. As the elastic parts 42 are not deformed, the connecting device 40 does not exert an elastic return force on the body 19 of the take-off assistance cylinder 17.

[0072] When the lifting device 3 is commanded to move from the retracted configuration to the extended configuration (configuration illustrated in the Figure 2 ), the first cylinders 7 are controlled to pivot the lifting arm 5 relative to the subframe 4 around the first pivot connection 12 in the first direction of rotation (direction of arrow A on the Figure 2 ).

[0073] Simultaneously, the take-off assist cylinder 17 is controlled to assist the first cylinders 7 during the start of the pivoting movement. In other words, the take-off assist cylinder 17 is controlled to apply a lifting force F to the lifting arm 5 in order to assist the take-off of the lifting arm 5.

[0074] For this purpose, the take-off assistance cylinder 17 is controlled to move the rod 9 relative to the body 19 in the first direction of translation (or direction of deployment) illustrated by the arrow C. For this purpose, pressurized fluid is injected into the first chamber 33, which has the effect of causing a movement of the piston 20 relative to the body 19 in the first direction of translation, from the extreme retracted position to the extreme deployed position.

[0075] During the movement of the rod 9, the second end 29 of the rod 9 comes into contact with the lifting arm 5 (as illustrated in the Figure 7). More precisely, the second end 29 of the rod 9 comes into contact with one of the lateral portions 31 of the lifting arm 5. The rod 9 exerts a thrust force on the lifting arm 5 which tends to assist the pivoting of the lifting arm 5 in the first direction of rotation (direction of the arrow A illustrated in the Figure 2 ).

[0076] From the moment when the rod 9 exerts a thrust force on the lifting arm 5, the lifting arm 5 exerts a reaction force in a direction opposite to the thrust force, which tends to push the take-off assistance cylinder 17 towards the subframe 4. This has the effect of placing the body 19 of the take-off assistance cylinder 17, and more precisely the convex portion 27 of the body 19 of the take-off assistance cylinder 17, against the bearing surface 32.

[0077] As the lifting arm 5 pivots relative to the subframe 4, the lifting arm 5 radially stresses the second end 29 of the rod 9, which causes the body 19 of the take-off assistance cylinder 17 to tilt relative to the support 18 in a first tilting direction (direction of the arrow E illustrated in the figure 8 ).

[0078] Due to the domed shape of the portion 35 of the external surface 30, the second end 29 of the rod 9 rolls on the lifting arm 5 as the lifting arm 5 pivots relative to the subframe 4.

[0079] Thus, as the lifting arm 5 is deployed, the angular orientation of the translation axis of the take-off assistance cylinder 17 changes relative to the support 18. The body 19 of the cylinder gradually changes from the first angular orientation (orientation illustrated in the Figure 7 ) to a second angular orientation (orientation shown in the figure 8 ).

[0080] During the tilting of the body 19 of the take-off assistance cylinder 17 relative to the support 18, the elastic parts 42 undergo deformation. Some of the elastic parts 42 are compressed while others of the elastic parts 42 are stretched. Thus, the connecting device 40 allows the tilting of the body 19 relative to the support 18 from the first angular orientation to the second angular orientation, while exerting an elastic return force tending to bring the body 19 back to the first angular orientation.

[0081] The progressive tilting of the body 19 relative to the support 18 is made possible by the fact that the spherical portion 27 rolls on the subframe 4 as the body 19 of the take-off assistance cylinder 17 is moved angularly relative to the support 18.

[0082] The piston 20 moves relative to the body 19 to the extreme deployed position (position illustrated in the figure 8). In this position, the body 19 of the take-off assistance cylinder 17 is oriented according to the second angular orientation.

[0083] Once the piston 20 has reached the extreme deployed position, the movement of the piston 20 ceases, while the lifting arm 5 continues to pivot relative to the subframe 4 in the first direction of rotation (direction of arrow A) thanks to the action of the first cylinders 7.

[0084] From this moment, the second end 29 of the rod 9 loses contact with the lifting arm 5. This has the consequence that the lifting arm 5 ceases to stress the second end 29 of the rod 9. The elastic return force exerted by the elastic parts 42 causes the body 19 to tilt relative to the support 18 in a second tilting direction (direction illustrated by the arrow F on the Figure 9 ) opposite to the first direction of tilting.

[0085] Under the effect of the elastic return force exerted by the elastic parts 42, the body 19 of the take-off assistance cylinder moves relative to the support 18 until it returns to the first angular orientation (orientation illustrated in the Figure 9 ).

[0086] Then, the take-off assistance cylinder 17 is controlled to move the rod 9 relative to the body 19 in a second translation direction (or retraction direction), illustrated by the arrow D on the Figure 10 , opposite to the first direction of translation, parallel to the translation axis. For this purpose, fluid is injected into the second chamber 34, which has the effect of causing a displacement of the piston 20 relative to the body 21 in the second direction of translation, from the extreme deployed position to the extreme retracted position.

[0087] Once the piston 20 has reached the extreme retracted position, the take-off aid cylinder is again in its initial position as illustrated in the Figure 6 .

Claims

1. Take-off assist actuator (17) comprising : - a support (18) suitable for being fixed to a subframe (4) of a lifting device (3), - a body (19), - a piston (20) moveably mounted in translation relative to the body (19) along a translation axis, - a rod (9) connected to the piston (20) and having an end (29) suitable for coming into contact with a lifting arm (5) of the lifting device (3), in order to push the lifting arm (5) during rotation of the lifting arm (5) relative to the subframe (4), and - a connecting device (40) connecting the body (19) to the support (18), the connecting device (40) allowing angular displacement of the body (19) relative to the support (18) during rotation of the lifting arm (5) relative to the subframe (4), wherein the body (19) has an external surface (25) having a convex portion (27) arranged to bear against a bearing surface (32) fixedly mounted relative to the subframe (4) when the rod (9) pushes the lifting arm (5), the convex portion (27) being suitable for rolling on the bearing surface (32) during the angular displacement of the body (19) relative to the support (18).

2. Take-off assist actuator (17) according to claim 1, wherein the connecting device (40) comprises a resilient part (42) capable of being deformed when the body (19) is displaced angularly from a first orientation to a second orientation, so as to generate a resilient return force tending to return the body (19) to the first orientation.

3. Take-off assist actuator according to claim 2, wherein the resilient part (42) comprises a block of resilient material.

4. Take-off assist actuator according to one of claims 2 and 3, wherein the connecting device (40) comprises several elastic parts (42) distributed around the body (19).

5. Take-off assist actuator according to one of claims 1 to 4, wherein the convex portion (27) has an ellipsoidal shape, preferably a spherical shape.

6. Take-off assist actuator according to one of claims 1 to 5, wherein the body (19) comprises a side wall (21) delimiting an internal cavity (24) in which the piston (20) is received, and a bottom (23) fixed to the side wall (21), the external surface (25) being an external surface of the bottom (23).

7. Take-off assist actuator according to claim 6, wherein the bottom (23) has a conical portion (26) extending from the side wall (21) to the convex portion (27).

8. Take-off assist actuator according to one of claims 6 and 7, wherein the bottom (23) is fixed to the side wall (21) by welding.

9. Take-off assist actuator according to one of claims 1 to 8, wherein the end (29) of the rod (9) has an external surface (30) having a convex portion (35) suitable for coming into contact with the lifting arm (4) in order to push the lifting arm (4).

10. Take-off assist actuator according to claim 9, wherein the convex portion (35) is suitable for rolling on a bearing surface (45) of the lifting arm (4) during angular displacement of the body (19) relative to the support (18).

11. Take-off assist actuator according to one of claims 9 and 10, wherein the convex portion (35) has an ellipsoidal shape.

12. Lifting device (3) comprising a subframe (4) intended to be fixed to the chassis (2) of a vehicle (1), a lifting arm (5) mounted on the subframe (4) via a pivot connection (12) allowing rotation of the lifting arm (5) relative to the subframe (4) between a retracted configuration and a deployed configuration, and a take-off assist actuator (17) according to one of claims 1 to 11 for pushing the lifting arm (5) during rotation of the lifting arm (5) relative to the subframe (4) towards the deployed configuration.

13. Lifting device (3) according to claim 12, wherein the lifting arm (5) comprises a connecting link (8) having two lateral portions (31), the lifting device (3) comprising two take-off assist actuators (17), each take-off assist actuator (17) having a rod (9) with an end (29) suitable for coming into contact with a respective lateral portion (31) of the connecting link (8), in order to push the lifting arm (5).

14. Lifting device (3) according to one of claims 12 and 13, wherein rotation of the lifting arm (5) from the retracted configuration to the deployed configuration causes angular displacement of the body (19) from the first orientation to a second orientation, and in which the connecting device (40) of the take-off assist actuator (17) comprises a resilient part (42) capable of being deformed when the body (19) is displaced angularly from the first orientation towards the second orientation, so as to generate a resilient return force tending to return the body (19) towards the first orientation.

15. Lifting or handling vehicle (1), comprising a chassis (2) and a lifting device (3), the lifting device comprising : - a subframe (4) fixed to the chassis (2), - a lifting arm (5) mounted on the subframe (4) by means of a pivot link (12) allowing rotation of the lifting arm (5) relative to the subframe (4), and - a take-off assist actuator (17) comprising a support (18) fixed to the subframe (4), a body (19), a piston (20) movably mounted in translation with respect to the body (19) along a translation axis, a rod (9) connected to the piston (20) and having an end (29) intended to come into contact with the lifting arm (5) in order to push the lifting arm (5) during rotation of the lifting arm (5) with respect to the subframe (4), and a connecting device (40) connecting the body (19) to the support (18), the connecting device allowing angular displacement of the body (19) relative to the support (18) during rotation of the lifting arm (5) relative to the subframe (4), wherein the body (19) has a first surface (25) and the vehicle comprises a second surface (32) fixedly mounted relative to the subframe (4), one of the first surface (25) and the second surface (32) comprises a convex portion (27) arranged to bear on the other of the first surface (25) and the second surface (32) when the rod (9) pushes the lifting arm (5), the convex portion (27) being suitable for rolling on the other of the first surface (25) and the second surface (32) during angular displacement of the body (19) relative to the support (18).

16. A vehicle as claimed in claim 15, wherein the lifting device (3) is a lifting device according to one of claims 12 to 14.