The invention relates to a self-propelled wrapping machine. In particular, the invention relates to a self-propelled wrapping machine, or robot, for wrapping with a film of cold stretchable plastics products or groups of products that are palletised or arranged on a pallet or on several superimposed pallets.

Such wrapping machines are generally used for wrapping a product or group of products of non-standard dimensions, mainly in small production runs, and in cramped productive environments in which static wrapping machines cannot be used.

Known self-propelled wrapping machines comprise a motorised self-propelled carriage including a supporting body and a guide body rotatably connected to the supporting body.

The supporting body, provided with a pair of non directional wheels, supports an upright on which a plastics film reel supplying unit is mounted that is provided with a film unwinding device .

The guide body includes a pair of directional- wheels connected to, and manoeuvred by, a steering, consisting of a curved manoeuvring bar provided at one end thereof with grasping handles .

In particular, the steering is movable between a lowered manoeuvring position, in which an operator can manoeuvre the wrapping machine manually between the pallets and a raised work position, in which the wrapping machine is stationary or can rotate automatically around the pallet for wrapping the product or the groups of products.

The guide body is further provided with a mechanical feeler that enables the carriage to follow a profile of the palletised products to be wrapped.

More precisely, the mechanical feeler comprises a rod, connected to the steering, to an end of which a contact wheel is fixed that is arranged in use for contacting the profile of the pallet Bed products to be wrapped. The rod is further connected to the supporting body by a spring.

The latter acts on the rod such as to maintain the contact wheel pressed against the products during wrapping and to guide the directional wheels of the carriage according to a work direction.

In use, for wrapping the products placed on a pallet, an operator positions the steering in the manoeuvring position and places the carriage near the pallet.

Subsequently, the operator positions the steering in the work position and activates the wrapping programme.

At this point, the carriage starts to rotate automatically around the pallet, following the profile of the pallet by means of the mechanical feeler.

The combination of the movement of the self propelling carriage around the pallet and of the vertical movement of the reel achieves helical wrapping of the products.

After wrapping has terminated, the operator repositions the steering in the manoeuvring position and directs the wrapping machine to another pallet of products to be wrapped.

A drawback of such wrapping machines is that they are heavy to be manoeuvred manually by an operator.

In fact, for manoeuvring such wrapping machines, the operator, after positioning the steering in the manoeuvring position, has to overcome a torque generated by the aforesaid spring on the steering, this torque tending to maintain the steering turned in the work direction.

In particular, this torque will be the greater, the harder the operator tries to turn the steering with respect to the aforesaid direction.

An object of the invention is to improve self-propelled wrapping machines ,

A further object is to provide a self-propelled wrapping machine that is easier to manoeuvre by an operator than are known wrapping machines. The invention provides a self-propelled wrapping machine as defined in independent claim 1.

Owing to the invention, it is possible to provide a self- propelled wrapping machine that is easier for an operator to manoeuvre than are known wrapping machines. In fact, said actuating means, by actuating on said manoeuvring means in contrast with said elastic means, lightens said manoeuvring means, making it easier for an operator to manoeuvre.

The invention also provides a self-propelled wrapping machine as defined in independent claim 12.

Owing to the invention, it is possible to provide a self- propelled wrapping machine that is easier for an operator to manoeuvre than are known wrapping machines . In fact , said driving means, by driving said spring in said non-operating configura ion, enables said manoeuvring means to be lightened, making the manoeuvring means easier for the operator to manoeuvre .

The invention can be better understood and implemented with reference to the attached drawings, which illustrate some embodiments thereof by way of non-limiting examples, in which:

Figure 1 is a perspective view of a self-propelled wrapping machine according to the invention;

Figure 2 is a perspective view of the machine in Figure 1 with some details removed and showing manoeuvring means included in this machine in a first operating position;

Figure 3 is a perspective view of the machine in Figure 1 with some details removed and showing the manoeuvring means in a second operating position;

Figure 4 is a section of the machine in Figure 1 in which the manoeuvring means is in the first operating position and directional wheels included in this machine are oriented in a first direction,-

Figure 5 is a vector diagram of the forces acting on the manoeuvring means in Figure ,- Figure 6 is a section of the machine in Figure 1 in which the manoeuvring means is in the second operating position and the directional wheels are oriented in the first direction;

Figure 7 is a vector diagram of the forces acting on the manoeuvring means in Figure 6;

Figure 8 is a section of the machine in Figure 1 in which the manoeuvring means is in the first operating position and the directional wheels are oriented in a second direction; Figure 9 is a vector diagram of the forces acting on the manoeuvring means in Figure 8 ;

Figure 10 is a section of the machine in Figure 1 in which the manoeuvring means is in the second operating position and the directional wheels are oriented in the second direction;

Figure 11 is a vector diagram of the forces acting on the manoeuvring means in Figure 10;

Figure 12 is a section of the machine in Figure 1 in which the manoeuvring means is in the first operating position and the directional wheels are oriented in a third direction; Figure 13 is a vector diagram of the forces acting on the manoeuvring means in Figure 12;

Figure 14 is a section of the machine in Figure 1 in which the manoeuvring means is in the second operating position and the directional wheels are oriented in the third direction;

Figure IB is a vector diagram of the forces acting on the manoeuvring means in Figure 14 ;

Figure 16 is a perspective view of a further embodiment of the machine in Figure 1 with certain details removed and showing manoeuvring means included in this machine in a first operating position;

Figure 17 is a perspective view of the further embodiment of the machine in Figure 1 with certain details removed and showing the manoeuvring means in a second operating pos tion; Figure 18 is a section of the further embodiment of the machine in Figure 1 in which the manoeuvring means is in the first operating position and directional wheels included in this machine are oriented in a first direction;

Figure 19 is a vector diagram of the force and of the torque acting on the manoeuvring means in Figure 18;

Figure 20 is a section of the further embodiment of the machine in Figure 1 in which the manoeuvring means is in the second operating position and the directional wheels are oriented in the first direction;

Figure 21 is a vector diagram of the force and of the torque acting on the manoeuvring means in Figure 20;

Figure 22 is a section of the further embodiment of the machine in Figure 1 in which the manoeuvring means is in the first operating position and the directional wheels are oriented in a second direction;

Figure 23 is a vector diagram of the force and of the torque acting on the manoeuvring means in Figure 22;

Figure 24 is a section of the further embodiment of the machine in Figure 1 in which the manoeuvring means is in the second operating position and the directional wheels are oriented in the second direction;

Figure 25 is a vector diagram of the force and of the torque acting on the manoeuvring means in Figure 2 /

Figure 26 is a section of the further embodiment of the machine in Figure 1 in which the manoeuvring means is in the first operating position and the directional wheels are oriented in a third direction;

Figure 27 is a vector diagram of the force and of the torque acting on the manoeuvring means in Figure 26;

Figure 28 is a section of the further embodiment of the machine in Figure 1 in which the manoeuvring means is in the second operating position and the directional wheels are oriented in the third direction;

Figure 29 is a vector diagram of the force and of the torque acting on the manoeuvring means in Figure 28. With reference to Figure 1, a self-propelled wrapping machine 1 is shown, also known as a wrapping robot, for wrapping with a film of plastics, for example a film of stretchable plastics, a product or groups of products palletised or arranged on a bench or on a pallet or on several superimposed pallets .

The wrapping machine l is generally used for wrapping a product or group of products of non-standard dimensions, mainly in small production runs, and in cramped production environments in which static wrapping machines cannot be used.

The wrapping machine 1 comprises a motorised self-propelled carriage 2.

The carriage 2 includes a supporting body 3 and a guide body 4 that is rotatably connected to the supporting body .

The supporting body 3, which is provided with a pair of non- directional wheels 5, supports an upright 6 on which a supply unit 7 of the reel of film is slidably mounted that is provided with an unwinding device, which is not shown, for unwinding the film.

The aforesaid guide body 4 includes a pair of directional wheels 9 steering around a substantially vertical rotation axis R (Figures 2, 3, 4, 6, 8, 10, 14, 16-18, 20, 22, 24, 26 and 28) .

In particular, the directional wheels 9 are mounted rotatably onto a support 10 of the guide body 4 connected to and manoeuvred by a steering 11.

The steering 11 consists of a curved manoeuvring bar 12 provided at one end thereof with grasping handles 13.

In particular, the steering 11 is rotatably connected to the support 10 and is rotatable around a substantially horizontal axis T (Figures 2, 3, 8, 10, 12, 14, 16-18, 20, 22, 24, 26 and 28) between a lowered manoeuvring position M (Figures 3, 6, 10, 14, 17, 20, 24, 28), in which an operator, who is not shown, can move the wrapping machine 1 manually between the pallets, and a raised work position L (Figures 1, 2, 4, 8, 12, 16, 18, 22, 26), in which the wrapping machine 1 is stationary or can rotate automatically, as will be explained below, around the pallet for wrapping the product or the groups of products.

The guide body 4 is further provided with a mechanical feeler 14 that enables the carriage 2 to follow a profile of the palletised products to be wrapped.

More precisely, the mechanical feeler 14 comprises a rod 15 connected, by the support 10, to the steering 11, to an end of which a contact wheel 16 is fixed that is arranged in use for contacting the profile of the palletised products to be wrap ed .

The rod 15 is further connected to the supporting body 3 by a spring 17 (Figures 2, 3, 4, 6, a, 10, 12, 14, 16-18, 20, 22, 24, 26 and 28) .

In particular, the spring 17 has an end pivoted in a first point fl of the rod 14 and a further end pivoted in a second point f2 of a frame 18, shown partially dashed, of the supporting body 3 (Figures 4, 6, 8, io, 12, 14) .

The spring 17 exerts on the steering 11, with respect to the rotation axis R, a torque CI defined by the vector product between an elastic force Fl exerted by the spring 17 on the steering 11 and an arm Bl of the force Fl with respect to the rotation axis R (Figures 5, 7, 9, 11, 13, 15) .

In particular, the force Fl has a direction defined by a straight line connecting the first point fl and the second point f2 and an intensity defined by the product of an elastic constant of the spring 17 and the elongation thereof .

In use, the torque CI acts on the rod 15 in such a manner as to maintain the contact wheel 16 pressed against the products during wrapping and to induce the steering 11 to orient the directional wheels 9 according to a set work direction D (Figures 4 and 6) in which the carriage 2 is movable along a curved path, which is not shown, in a clockwise direction. In particular, the torque Cl exerted by the spring 17 increases by steering the steering 11 from the work direction D to a direction Dl (Figures 8, 10) in which the carriage 2 is movable along a rectilinear path, which is not shown, and decreases by steering the steering 11 from the direction Dl to a further direction D2 (Figures 12, 14) in which the carriage 2 is movable along a further curved path, which is not shown, in an anticlockwise direction.

The wrapping machine 1 further comprises a further spring 19 having an end pivoted in a third point f3 of the steering 11 and a further end pivoted in a fourth point f4 of the frame IS (Figures 4, 6, 8, 10, 12, 14) .

in use, the steering 11 drives the further spring 19 between a non-operating configuration NW (Figures 4, 8 and 12) and an operating configuration W (Figures 5, 9 and 13) .

In particular, when the steering 11 is raised into the work position L, the distance between the third point f3 and the fourth point f4 is such as not to cause any elongation of the further spring 19, which is thus in the non-operating configuration NW.

This means that, in the non-operating configuration NW, the further spring 19 does not exert on the steering 11, with respect to the rotation axis R, any torque (Figures 4, 8, 12) .

In one embodiment of the invention, which is not shown, the distance between the third point f3 and the fourth point f4 , when the steering 11 is raised into the work position L, is such as to cause only minimal elongation of the further spring 19, This means that, in the non-operating configuration NW of this embodiment, the further spring 19 exerts on the steering 11, with respect to the rotation axis R, a further very small torque, in particular much less than the torque Cl, such as not to be a hindrance to the automatic movement of the wrapping machine 1 during wrap ing . Vice versa, when the steering 11 is lowered into the manoeuvring position M, it increases the distance between the third point f3 and the fourth point £4, this increasing the further spring 19, which is thus in the operating configuration W (Figures 5, 9, 13) .

In this operating configuration W, the further spring 19 exerts on the steering 11, with respect to the rotation axis R, a further torque C2 determined by the vector product between a further elastic force F2 exerted by the further spring 19 on the steering 11 and a further arm B2 of the further force F2 with respect to the rotation axis R (Figures 5, 9, 13) .

In particular, the further force F2 has a further direction defined by a further straight line connecting the third point f3 and the fourth point f and a further intensity defined by the product between a further elastic constant of the further spring 19 and the elongation thereof.

This further torque C2 , opposite the torque CI, acts on the steering 11 such as to contrast the torque CI such as to promote the manoeuvrab lity of the steering 11 (Figures 5, 9, 13) .

In particular, the further spring 19 is configured in such a manner that the further torque C2 is greater than the torque CI (Figures 6 and 7) during movement of the steering 11 from the work direction D to the direction Dl, such that when the steering 11 is in the manoeuvring position M it is induced to orient the directional wheels 9 in the direction Dl; such that the further torque C2 is substantially the same as, i.e. balances, the torque CI when the steering 11 orients the directional wheels in the direction Dl (Figures 10 and 11) ; such that the further torque C2 is less than torque CI during movement of the steering 11 from the direction Dl to the further direction D2 (Figures 14 and 15) such that when the steering 11 is in the manoeuvring position it is induced to orient the directional wheels 9 in the direction Dl. The wrapping machine 1 further comprises a locking system, which is not shown, to lock the steering 11 in the manoeuvring position M so as to maintain the further spring 19 in the operating configuration W.

In one embodiment of the invention, which is not shown, the further spring 19 acts below the rotation axis T of the steering 11, this enabling, in the operating configuration w, the steering 11 to be maintained in the manoeuvring position M.

The operation of the further spring 19 is disclosed in greater detail with reference to Figures 4 to 15.

In Figures 4 and 6 the directional wheels 9 are shown in a first operating condition 0P1 in which they are oriented in the work direction D to move the carriage 2 along the aforesaid curved path in a clockwise direction.

In the first operating condition OPi, when the steering 11 is in the work position L and so the further spring 19 is in the non-operating conf guration NW (Figure 4) , on the steering 11 only the torque CI acts that is exerted by the spring 17 that induces the steering 11 to maintain the directional wheels 9 oriented in the work direction D (Figure 5) .

Vice versa, when the steering 11 is in the manoeuvring position M and thus the further spring 19 is in the operating configuration (Figure 6) , both the torque CI exerted by the spring 17 and the further torque C2, opposite the torque CI, exerted by the further spring 19 act on the steering 11 (Figure 7) .

The further torque C2, by contrasting the torque C , enables the steering 11 to be steered easily with respect to the work direction D.

As already said, in the first operating condition OPI, the further torque C2 is greater than the torque CI, this inducing the steering 11, maintained in the manoeuvring position M and without the intervention of an operator, to orient the directional wheels 9 in the direction Dl. In Figures 8 and 10 the directional wheels 9 are shown in a second operating condition OP2 in which they are oriented in the direction Dl to move the carriage 2 along the aforesaid rectilinear path.

In the second operating condition OP , when the steering 11 is in the work position L and thus the further spring 19 is in the non-operating conf guration N (Figure 8) , only the torque CI acts on the steering 11, which torque CI is exerted by the spring 17 that induces the steering 11 to orient the directional wheels 9 in the work direction D (Figure 9) .

Vice versa, when the steering 11 is in the manoeuvring position M and thus the further spring 19 is in the operating conf guration W (Figure 10) , both the torque Cl exerted by the spring 17 and the further torque C2, opposite the torque Cl, exerted by the further spring 19 (Figure 11) act on the steering 11.

As in the second operating condition OP2 the further torque C2 is substantially the same as, i.e. substantially balances, the torque Cl, the steering 11 is induced to maintain the directional wheels 9 oriented in the direction Dl, without the operator exerting any torque on the steering 11.

In Figures 12 and 14 there are shown the directional wheels 9 in a third operating condition OP3 in which they are oriented in the further direction D2 to move the carriage 2 along the further curved path in an anticlockwise direction. In the third operating condition OP3, when the steering 11 is in the work position L and thus the further spring 19 is in the non-operating configuration NW (Figure 12) , on the steering 11 only the torque Cl acts that is exerted by the spring 17 that induces the steering 11 to orient the directional wheels 9 oriented in the work direction D (Figure 13) .

Vice versa, when the steering 11 is in the manoeuvring position M and thus the further spring 19 is in the operating configuration W (Figure 14), both the torque C exerted by the spring 17 and the further torque C2 , opposite the torque CI, exerted by the further spring 19 (Figure 15) act on the steering 11.

The further torque C2, by contrasting the torque CI, enables the steering 11 to be steered easily with respect to the further direction D2.

As already said, in the third operating condition 0P3, the further torque C2 is less than the torque CI, this inducing the steering 11, maintained in the manoeuvring position M and without the invention of an operator, to orient the directional wheels 9 in the direction Dl ,

In use, for wrapping the products placed on a pallet, an operator positions the steering 11 in the manoeuvring position M and places the carriage 2 near the pallet.

Subsequently, the operator positions the steering 11 in the work position L, in which the further spring 19 is in the non-operating conf guration NW, and activates the wrapping programme .

At this point, the carriage 2 starts to rotate automatically around the pallet following the profile of the pallet by means of the mechanical feeler 14.

The combination of the motion of the self-propelled carriage 2 around the pallet and of the vertical motion of the reel achieves helical wrapping of the products .

After wrapping has terminated, the operator repositions the steering 11 in the manoeuvring position M, in which the further spring 19 is in the operating configuration W, and manoeuvres the wrapping machine 1 towards another pallet of products to be wrapped.

It should be noted how, owing to the invention, it is possible to provide a self-propelled wrapping machine 1 that is easier for an operator to manoeuvre than are known self- propelled wrapping machines .

In fact, the operator, by manually moving the steering n from the work position L into the manoeuvring position M, drives the further spring 19 to the operating configurat on W in which the further spring 19, by acting on the steering 11 in contrast with the spring 17, lightens the steering 11, and thus the guide body 4, facilitating the manoeuvrability thereof .

In one embodiment of the invention, which is not shown, instead of the further spring 19 a mechanical or pneumatic or hydraulic actuator is provided that is drivable, as disclosed for the further spring 19, by the steering 11.

With reference to Figures 16 to 29 a further embodiment of the wrapping machine 1 is shown.

In this further embodiment, the spring 17 has an end pivoted in a point gl of a bracket 20 and a further end pivoted in a further point g2, substantially coinciding with the second point £2, of the frame IS of the supporting body 3 (Figures 18, 20, 22, 24, 26, 28) .

In this further embodiment, the spring 17 exerts on the steering 11, with respect to the rotation axis R, a first torque Tl defined by the vector product between a first elastic force Zl exerted by the spring 17 on the steering 11 and a first arm Al of the first force Zl with respect to the rotation axis R (Figures 19, 21, 23, 25, 27, 29) .

In particular, the first force Zl has an application direction dl, represented by a dashed line in Figures 18, 22, 26, defined by a straight line joining the point gl and the further point g2 and an intensity defined by the product between an elastic constant of the spring 17 and the elongation thereof .

In use, the first torque Tl acts on the rod 15 such as to maintain the contact wheel 16 pressed against the products during wrapping and to induce the steering 11 to orient the directional wheels 9 according to the work direction D (Figures 18 and 20) in which the carriage 2 is movable along a curved path, which is not shown, in a clockwise direction. In particular, the first torque Tl exerted by the spring 17 increases by steering the steering 11 from the work direction D to the direction Dl (Figures; 22, 24) in which the carriage 2 is movable along a rectilinear path, which is not shown, and decreases by steering the steering n from the direction Dl to the further direction D2 (Figures 26, 28) in which the carriage 2 is movable along a further curved path, which is not shown, in an anticlockwise direction.

In this further embodiment, the wrapping machine 1 further comprises a slide 21 that is slidable along a guide 22, for example a rectilinear guide (Figures 16, 17, 18, 20, 22, 24, 26 and 28) .

The guide 22 is connected on the one side to an end of the rod 15 opposite the end supporting the contact wheel 16, and on the other to the support 10.

The bracket 20 and an articulated arm 23 are rotatably connected to the slide 21.

The articulated arm 23 comprises a first rod 24, a second rod 25 and a third rod 26.

In particular, the first rod 24, which is, for example, rectilinear, has an end that is rotatably connected to the slide 21 and a further end that is connected to the second rod 25.

The second rod 25 has a free end that is rotatably connected to the support 10 and an intermediate portion that is rotatably connected to the third rod 26.

Finally, the latter has a free end that is rotatably connected to the steering 11.

In this further embodiment, in use, the steering 11 drives the spring 17, by means of the slide 21 moved by means of the articulated arm 23 connected to the steering 11, between a first operating configuration Wl (Figures 16, 18, 22 and 26) and a first non-operating configuration NWl (Figures 17, 19, 23 and 27) .

In particular, by driving the steering 11 betwee 'the first operating configuration Wl and the first non-operating configuration NWl, the first torque Tl is reduced, inasmuch as the orientation of the application direction of the force exerted by the spring 17 is varied, which reduces the arm of this force, and/or the distance decreases between the point gl and the further point g2, which reduces the elongation, and thus the intensity, of this force.

In the first operating conf guration Wl, the steering 11 is raised into the work position L and the slide 21, driven by the steering 11 by means of the articulated arm 23, is in a first position Pi (Figures 16, 18, 22, 26) .

In the first operating configura on Wl, the spring 17 exerts on the steering 11, with respect to the rotation axis R, the first torque Tl (Figures 19, 23, 27),

In the first non-operating configura ion NW1, the steering 11 is lowered into the manoeuvring position M and the slide 21 driven by the steering 11 by means of the articulated arm 23, is in a second position P2 (Figures 17, 20, 24, 28) . In the first non-operating configuration NW1, the spring 17 exerts on the steering 11, with respect to the rotation axis R, a second torque T2, that is less than the first torque Tl, determined by the vector product between a second elastic force 7,2. exerted by the spring 17 on the steering 11 and a second arm A2 of the second force Z2 with respect to the rotation axis R (Figures 21, 25, 29) ,

In particular, the second force Z2 has a further application direction d2, represented by a dashed line in Figures 20, 24, 28, defined by a further straight line joining point gl with the further point g2 and a further intensity defined by the product between a further elastic constant of the spring 17 and the elongation thereof.

This second torque T2, which is less than the first torque Tl, makes it easier for an operator to manoeuvre the steering 11.

Also in this further embodiment, the wrapping machine 1 comprises a locking system, which is not shown, for locking the steering 11 in the manoeuvring position so as to maintain the spring 17 in the first non-operating configuration NW1,

The operation of this further embodiment is disclosed in greater detail with reference to Figures 18 to 29.

In Figures 18 and 20 there are shown the directional wheels 9 in a further first operating condition O 1 in which they are oriented in the work direction D to move the carriage 2 along the aforesaid curved path in a clockwise direction. In the further first operating condition OW1, when the steering 11 is in the work position L and thus the spring 17 is in the first operating configuration Wl (Figure 18) , on the steering 11 the first torque Tl acts that is exerted by the spring 17 that induces the steering 11 to maintain the directional wheels 9 oriented in the work direction D (Figure 19) .

Vice versa, when the steering 11 is in the manoeuvring position M and thus the spring 17 is in the first non- operating configuration NW1 (Figure 20) , the second torque T2 acts on the steering 11. This second torque T2 is less than the first torque Tl inasmuch as the second arm A2 is less than the first arm Al.

The second torque T2 , which is less than the first torque Tl; enables the steering 11 to be steered more easily with respect to the work direction D.

In the further first operating condition OW1, the second torque T2 induces the steering 11, maintained in the manoeuvring position M and without the intervention of an operator, to orient the directional wheels 9 in the work direction D.

In Figures 22 and 24 the directional wheels 9 are shown in a further second operating condition O 2 in which they are oriented in the direction Dl to move the carriage 2 along the aforesaid rectilinear path.

In the further second operating condition OW2, when the steering 11 is in the work position L and thus the spring 17 is in the first operating configuration Wl (Figure 22) , o the steering 11 acts the first torque Tl exerted by the spring 17 that induces the steering 11 to orient the directional wheels 9 according to the work direction D {Figure 23) .

Vice versa, when the steering 11 is in the manoeuvring position M and thus the spring 17 is in the first non- Operating configuration NW1 (Figure 24) , the second torque T2 acts on the steering 11. This second torque T2 is less than the first torque Tl inasmuch as the second arm A2 is less than the first arm Al and the second force Z2 is less than the first force Zl.

The second torque T2, which is less than the first torque Tl, enables the steering 11 to be steered more easily with respect to the work direction D.

In the further second operating condition OW2 , the second torque T2 induces the steering 11, maintained in the manoeuvring position M and without the intervention of an operator, to orient the directional wheels 9 according to the work direction D.

In Figures 26 and 28 the directional wheels 9 are shown in a further third operating condition OW3 in which they are oriented in the further direction D2 to move the carriage 2 along the further curved path in an anticlockwise direction. In the further third operating condition OW3, when the steering 11 is in the work position L and thus the spring 17 is in the first operating configuration Wl (Figure 26) , on the steering 11 acts the first torque Tl exerted by the spring 17 that induces the steering 11 to orient the directional wheels 9 in the work direction D (Figure 27) , Vice versa, when the steering 11 is i the manoeuvring position M and thus the spring 17 is in the first non- operating configuration NW1 (Figure 28), the second torque T2 acts on the steering 11, This second torque T2 is less than the first torque Tl inasmuch as the second arm A2 is less than the first arm Al and the second force Z2 is less than the first force Zl. The second torque T2, which is less than the first torque Tl, enables the steering 11 to be steered more easily with respect to the work direction D.

In the further third operating condition O 3 , the second torque T2 induces the steering 11, maintained in the manoeuvring position M and without the intervention of an operator, to orient the directional wheels 9 in the work direction D.

In use, for wrapping the products placed on a pallet, an operator positions the steering 11 in the manoeuvring position M and places the carriage 2 near the pallet.

Subsequently, the operator positions the steering 11 in the work position L, in which the further spring 19 is in the first operating configuration Wl, and activates the wrapping programme .

At this point, the carriage 2 starts to rotate automatically around the pallet following the profile of the pallet by means of the mechanical feeler 1 .

The combination of the motion of the self-propelled carriage 2 around the pallet and of the vertical motion of the reel achieves helical wrapping of the products.

After wrapping has terminated, the operator repositions the steering 11 in the manoeuvring position M, in which the spring 17 is in the first non-operating configuration NW1, and manoeuvres the wrapping machine l towards another pallet of products to be wrapped.

It should be noted how, owing to the invention, it is possible to provide a self-propelled wrapping machine 1 that is easier for an operator to manoeuvre than known self- propelled wrapping machines.

In fact, by moving the steering 11 manually from the work position L into the manoeuvring position M, the operator drives, by means of the articulated arm 23 and the slide 21, the spring 17 into the first non-operating configuration NW1 in which the spring 17 exerts on the steering 11 a second torque T2, which is less than the first torque Tl, thus lightening the steering 11 and thus facilitating the manoeuvrability thereof.

In one embodiment of the invention, which is not shown, the articulated arm 23 and the slide 21 are configured in such a manner that, in the first non-operating configuration NW1, the application direction of the force exerted by the spring 17 intersects the rotation axis R of the directional wheels. In this manner the second arm A2 and thus the second torque T2 are cancelled.

In another embodiment of the invention, which is not shown, the articulated arm 23 and the slide 21 are configured in such a manner that, in the first non-operating configuration NW1, the distance between the point gl and the further point g2 is such as not to cause any elongation of the spring 17. In this manner the second force Z2 and thus the second torque T2 are cancelled.

In still another embodiment of the invention, which is not shown, the articulated arm 23 and the slide 21 are configured in such a manner that, in the first non-operating configuration NW1, the application direction of the force exerted by the spring 17 intersects the rotation axis of the directional wheels and the distance between the point gl and the further point g2 is such as not to cause any elongation of the spring 17. In this manner both the second arm A2 and the second force Z2 are cancelled, this cancelling the second torque T2.