Lifting bridge, in particular for motor vehicle

Abstract

The invention relates to an elevator, in particular for a motor vehicle, comprising at least one lane (2); two legs (4, 4 ') hinged to the at least one lane (2) and each made of a single arm; at least one actuator (30) associated with each leg (4, 4 ') and configured to vary the inclination of each leg (4, 4') with respect to the horizontal so as to raise and lower the at least one lane (2); and a synchronous control unit for all the actuators (30); the invention is characterized in that: the two legs (4, 4 ') connected to the at least one lane (2) are arranged symmetrically with respect to the transverse median plane of the elevator, the lower end of each leg (4, 4') is hinged to a base (8) by connecting to a first fixed transverse axis (10) to be anchored to the floor, the upper end of each leg (4, 4 ') is hinged to a pulley (14) by connecting to a second transverse axis (12) to be anchored to the floor, and the lower end of each leg (4, 4') is hinged to the base (8) by connecting to a second fixed transverse axis (12) to be anchored to the floor. The pulleys (14) slide along the respective lane (2),-an additional connection is provided between at least one of the two legs (4, 4 ') of each lane (2) and a lane part which forms an angle of less than 90 DEG with the leg (4) in the raised elevator configuration, the additional connection comprises at least one rod (20, 20 ', 20' ', 20 '''), one end of which is hinged to the leg (4) by connecting to a third transverse axis (22) and the other end of which is hinged to the lane (2) by connecting to a fourth fixed transverse axis (24),-the at least one rod (20, 20 ', 20' ', 20''') is provided with elastic means, the elastic means are configured to absorb a change in distance between a third shaft (22), in which the rod itself is hinged to said legs (4, 4 '), and a fourth shaft (24), in which the rod itself is hinged to said at least one lane (2), the change in distance being caused by a change in the geometry of the elevator. Changes in the geometry of the elevator are due to load imbalance or in any case due to the function of the elevator and are counteracted by the presence of vehicles placed on the raised lane.

Description

[0001] The invention relates to a motor vehicle lift.

[0002] Lifts for motor vehicles are known, comprising a pair of carriageways, on which the motor vehicle to be lifted rests, and two legs articulated above to each carriageway and below to a base, which may consist of side members anchored or resting on the floor, or the floor itself, suitably configured and reinforced so as to support the legs in an articulated manner.

[0003] Each leg may consist of a single rigid element or arm, articulated below to the base and above to the track; or may consist of several rigid elements or arms, articulated to each other and also articulated below to the base and above to the track.

[0004] The upward and downward movement of the two lanes is usually achieved by hydraulic actuators placed between the legs and the lanes, or between the legs and the base, or between the articulated arms that constitute each leg.

[0005] A hydraulic power unit connected to the actuator is equipped to introduce oil into and exhaust oil from the actuator, thereby causing synchronized upward and downward movement of the track relative to the base.

[0006] There are various types of lifts: for example, a so-called "parallelogram" lift is described in US 4848732. It comprises two base longitudinal members anchored or placed on the floor, two hoistable carriageways relative to the base longitudinal members and two or more pairs of legs, each pair of legs consisting of a single element articulated below to a base beam (spar) and above to the respective carriageway.

[0007] In these lifts, the lifting of the lanes relative to the side members is achieved by placing an actuator between two homologous legs and the corresponding lanes. As the actuators lengthen and shorten as hydraulic fluid is introduced into or discharged from the actuators, the angle formed by each leg and the lane in which each actuator is placed changes, which causes a deformation of the parallelogram formed by each beam, the corresponding lane and the two legs hinged to the two, resulting in a substantially translational movement of the lanes with a vertical component.

[0008] In this type of lift, the trend curve representing the pressure of the hydraulic fluid in the actuator as a function of the lift travel of the carriage is downward, in the sense that the greater the height reached by the carriage, the lower the pressure in the hydraulic system that keeps it lifted, which is advantageous because the pressure on the actuator and on the mechanical safety locking device of the lifted lift is lower than the pressure required to raise the lift.

[0009] This type of lift has been widely promoted due to its simple structure and operational reliability, but it also highlights some disadvantages, in particular:

[0010] - during the raising of the carriageway, there is a horizontal component to its movement and the consequent overall dimensions of the raised lift being significantly greater than those of the lowered lift, thus requiring a larger space to house the lift than would be required for a lift in which the carriageway moves in a substantially vertical motion;

[0011] - the space occupied by the beams at ground level, which prevents the free passage of the operator under the raised lift; this disadvantage can be overcome by eliminating the longitudinal members and hinge the legs directly to the floor, in which case it is necessary to prepare for this installation, for example by embedding concrete beams in the floor to achieve the structural connection for the legs;

[0012] - Due to the integral nature of the outriggers, the maximum height that the lane can reach is limited and cannot be made excessively long without negative structural and operational impacts on the lift;

[0013] -When each lifting jack is placed between the outrigger and the track, the track actually has four or more restraint points, so statically indeterminate behavior occurs.

[0014] Another known type of lift, such as that described in US 8286944, is characterized in that each leg is formed by two arms of substantially equal length, articulated at one end to each other and at the other end to the corresponding base and track. In these known lifts, the track is moved in a substantially vertical motion, and the hydraulic actuator for raising and lowering the track is placed between the two arms of each leg, which are also assisted by other articulated arms, having the function of stabilizing the leg-track complex and providing further support for the track, which is in fact supported at four points, namely two points for each leg.

[0015] In these known lifts, the positioning of the base to which the legs are articulated requires a high degree of precision in order to allow full raising and lowering of the lift.

[0016] Furthermore, the support of each track at four points implies an indeterminate constraint which, in the event of deformations of the track or simply in the event that the track reaches different heights due to load imbalances or imbalances generated by the actuator synchronization system, gives rise to indeterminate forces which involve forces related to the constraints and deformations of the lift structure and which can only be partially reduced by the elastic compensation system of the legs.

[0017] Another disadvantage is that the trend curve representing the pressure of the hydraulic fluid supplied to the actuator as a function of the lift travel of the carriageway first decreases until it reaches a minimum value and then starts to increase again until it reaches almost the high starting value when the lift is fully raised. This means that the pressure on the actuator and the mechanical safety locking device of the raised lift is greatest when the lift is raised, i.e. in active working order.

[0018] Other disadvantages of this known type of lift are the high complexity of manufacture, associated with the large number of components which must be connected to one another and which inevitably involve plays and inaccuracies in their mutual movement.

[0019] Also known from EP 3995437 is a lift for motor vehicles comprising a pair of rails, each supported by a pair of legs placed symmetrically relative to a transverse centerline plane of the lift. Each leg comprises a main rigid arm, articulated at the bottom to a base with a first fixed transverse axis and at the top to the rail with a second transverse axis, which slides longitudinally along the rail. Each leg also comprises an auxiliary arm, articulated at the top to the rail with a third fixed transverse axis and at the bottom to the main arm with a fourth fixed transverse axis, at the same distance from the second and third transverse axes. Each actuator for lifting the lift is inserted between the third transverse axis and a fifth transverse axis different from the fourth axis and is fixed relative to the main arm.

[0020] The shortcoming of this known lifter is the hyperstatic connection of lifter track and legs and the bulk of legs along its length. In addition, these lifters also have other shortcomings related to the described lifter according to US 8286944.

[0021] Finally, other known lifts also have legs consisting of two or more elements connected to each other by an articulation system involving a non-vertical movement of the track and the legs are usually arranged asymmetrically with respect to the track relative to the transverse median plane of each track; and this asymmetry in turn determines the asymmetrical behavior of the track with respect to the load.

[0022] The present invention aims at creating a lift for motor vehicles which substantially eliminates all the drawbacks discernible in lifts of known type, while retaining the associated advantageous aspects.

[0023] More specifically, the object of the invention is to create a lift in which the movement of the carriageway occurs in a substantially vertical direction.

[0024] Another object of the invention is to create a lift in which each leg consists of a single element, articulated below with the base and above with the carriageway of the lift, and which therefore has limited manufacturing complexity.

[0025] Another object of the invention is to create a lift capable of reaching a maximum height of the driveway equal to that achieved by current lifts using legs consisting of a single arm but having a greater overall length.

[0026] Another object of the invention is to create a lift capable of reaching a maximum height of the driveway equal to that achieved by current lifts using legs composed of multiple articulated arms.

[0027] Another object of the present invention is to provide an elevator in which the support of the rails by the legs is of a balanced type, eliminating stresses associated with binding and deformation of the elevator structure.

[0028] Another object of the invention is to create a lift that does not hinder the free passage of the operator underneath the raised lift.

[0029] Another object of the invention is to create an elevator that has a dissipative behavior in the event of a seismic event.

[0030] Another object of the present invention is to create a lift that reduces deformation and structural stresses that occur on the carriageway when the lift is raised.

[0031] All these objects, and others which will ensue from the following description, are achieved according to the invention, jointly or individually, by a lift for motor vehicles as defined in claim 1.

[0032] The present invention is further illustrated below by some preferred practical embodiments, which are described with reference to the accompanying drawings for illustrative and non-limiting purposes only, in which:

[0033] Figure 1 A perspective view schematically shows a lift in a raised state according to a first embodiment of the present invention;

[0034] Figure 2 The lift is always shown in perspective, but in a lowered position;

[0035] Figure 3 An enlarged side view of the right side of the lift is shown in a raised position with the carriageway partially cut off;

[0036] Figure 4 Shown according to Figure 3 Vertical section IV-IV;

[0037] Figure 5 Shown with Figure 4 The same view, but in a lowered state;

[0038] Figure 6 With Figure 3 The same view shows its variant structure;

[0039] Figure 7 Shows Figure 6 A specific embodiment of the components of the medium lift;

[0040] Figure 8 Different embodiments of the same component are shown;

[0041] Fig. 9 Another embodiment of the same component is shown;

[0042] Fig.10 shows a lift according to the invention in a different configuration, using the same principles already described with reference to the previous embodiments shown in the previous figures; and

[0043] Fig.11 The right side of the lift is shown on a larger scale in this different configuration but in a different embodiment.

[0044] from Figures 1 to 5 As can be seen, the lift according to the invention comprises two carriageways 2 and two pairs of legs 4, 4', the carriageways being intended to accommodate motor vehicles or in any case loads to be lifted, each leg being constituted by a single element configured and dimensioned according to the specific stresses arising from the project. Preferably, each leg 4, 4' is formed by metal sheets of suitable shape and thickness, welded together to define a box-shaped element capable of effectively resisting the bending and torsional stresses typical of lifts, in particular when they are subjected to the stresses of eccentric loads, which may occur when the lift is equipped with auxiliary crosspieces connecting the carriageways, which are mainly loaded on the inner edges of the carriageways. In fact, for this purpose, it is advantageous to provide the carriageways 2 with a profile such as projecting longitudinal rails 6, which are very useful for supporting these auxiliary crosspieces (not shown, since they are conventional in themselves) which are usually required to facilitate the work of the operator on the vehicle placed on the raised lift carriageway.

[0045] Each leg 4, 4' is articulated below with a base 8, preferably anchored to the floor, and each leg 4, 4' is articulated above with the corresponding track 2. However, while the lower articulation of each leg 4, 4' with the relative base 8 occurs at a fixed transverse axis 10 (first articulation axis), the upper articulation of each leg 4, 4' with the relative track 2 occurs at a position corresponding to an articulation axis 12 (second articulation axis) located in a sliding carriage 14, preferably with bearings 16 sliding along a longitudinal channel 18 obtained in the track 2.

[0046] exist Figures 1 to 5In the illustrated embodiment, the leg 4 of each lane 2 is provided with a rigid rod 20, or preferably two rigid rods 20, one end of the rigid rod 20 being hinged to both sides of the leg 4 and the other end being hinged to a portion of the lane 2 forming an angle less than 90° with the leg 4.

[0047] The articulation of the rod 20 or each rod 20 to the leg 4 is achieved by association with a fixed transverse axis 22 (third articulation axis), which is preferably situated in a plane passing through the first articulation axis 10 and the second articulation axis 12. The articulation of each rod 20 to the track 2 is achieved by association with a fixed transverse axis 24 (fourth articulation axis), which is advantageously chosen so that the distance between the two axes 22 and 24 is equal to the distance between the two axes 22 and 12.

[0048] More specifically, the connection between each rod 20 and a leg 4, 4' is achieved by the insertion of a shock-absorbing bush, which in fact consists of a tubular sleeve 26 made of elastic material, in particular a dense rubber of the NBR or SBR type vulcanized or pressed onto a metal element and placed between an internal pin integral with each leg 4, 4' and a hollow cylinder integral with the end of the rod 20, the longitudinal axis of which coincides with the third articulation axis 22. In this way, the articulation between the rod 20 and the respective leg 4, 4' is of the damping type, in the sense that a limited elastic movement of the rod 20 in two directions perpendicular to the articulation axis 22 of the leg 4, 4' is allowed.

[0049] However, in the case where the bushing 26 is substantially unstressed, the distance between the third articulation axis 22 and the second articulation axis 12 is substantially equal to the distance between the third articulation axis 22 and the fourth articulation axis 24 .

[0050] However, the same result can be obtained if the shock-absorbing bushing is placed at the connection between the rod 20 and the track 2, or even better at both connections between the rod 20, the legs 4, 4' and the track 2.

[0051] Preferably, the third articulation axis 22 is also equidistant from the first articulation axis 10 and the second articulation axis 12 .

[0052] Furthermore, an actuator 30 is connected to each base 8 by means of a connection with a fixed transverse axis 28 (fifth articulation axis) different from the axis 10, the actuator 30 being preferably of the hydraulic type, constituted by a jack, the articulation rod of which is connected to the respective leg 4, 4' by means of a connection with a transverse axis 32 (sixth articulation axis), preferably situated approximately in the central region of the leg itself. The two actuators 30 applied to the two legs 4, 4' are connected to a power supply and a control unit (not shown) and are synchronized with each other in their movements by means of a shunt or an electronic system, which are themselves conventional and are not further described. However, it is also conceivable that not one but two side-by-side actuators 30 may be applied to the same leg 4, 4', their movements obviously being synchronized.

[0053] The shape and size of the legs 4, 4' and base 8 of the track 2 are preferably such that when each track 2 is in the fully lowered position, it actually rests on the floor, housing the base 8, legs 4, 4', actuator 18 and rod 22, from which Figure 4 and Figure 5 This can be seen in the comparison.

[0054] In addition, the geometry of the elevator is such that the fifth articulation axis 28 of the actuator 30 at the base 8 is placed at a lower height than the first articulation axis 10 of the legs 4, 4' at the base 8; when the elevator is fully lowered, the second articulation axis 12 of each leg 4, 4' connected to the corresponding slide 14 is at a height not higher than the first articulation axis 10 of the leg itself at the base 8, and the articulation axis 32 of the actuator 30 at the legs 4, 4' is at a height not lower than the articulation axis 28 of the actuator itself at the base 8.

[0055] Furthermore, the articulation axis 32 of each actuator 30 connected to the relative leg 4 , 4 ′ is preferably always located at a higher level than the articulation axis 28 of the actuator connected to the base 8 , when each rail is in its lowest position.

[0056] The operation of the lift according to the invention in the now described embodiment can be better understood if we first distinguish between the case where the lift loads the motor vehicle in a balanced manner and the case where the lift loads the motor vehicle in an unbalanced manner, for example the front of the vehicle is heavier than the rear.

[0057] In the ideal case of perfectly balanced loads and without tolerances in the synchronization system of the lifting actuators 30 , during the raising and lowering of the lift, the track 2 moves in a perfectly vertical translational movement and remains perfectly centered in the longitudinal direction relative to the legs 4 , 4 ′.

[0058] However, in real situations, the loads are almost always unbalanced and there are always unavoidable intervention tolerances in the synchronization system of the actuators 30. If, under these conditions, the track 2 is connected to the legs 4, 4' only by means of a trolley 14, the inevitably greater deformation of the most heavily loaded leg and its different inclination relative to the other leg will cause each track 2 to slide uncontrollably relative to its leg 4, 4', within the limits of the system's degrees of freedom, in a direction consistent with the movement of the upper end of the leg 4 or leg 4', at which point greater friction will occur with the track 2, regardless of whether the load on this leg is large or small.

[0059] However, the presence of this further constraint between each lane 2 and the corresponding leg 4, 4', constituted by a rod 20 or a plurality of rods 20, means that if, for example due to load imbalance, one of the legs 4 or 4' of each lane 2 is less inclined than the other, a control of the longitudinal sliding of the lane 2 is implemented, in the sense that this sliding always occurs towards the leg 4 or 4' with the less inclined slope and the extent of the sliding is related to the geometry of the system.

[0060] In this way, a series of advantages that were previously unattainable with conventional elevators can be obtained with a fairly simple elevator structure and safe and reliable operation.

[0061] One advantage is that the movement of each track 2 of the elevator relative to its legs 4, 4' can be controlled according to a defined movement law related to the geometry of the system, depending on the different inclinations of the system relative to the horizontal.

[0062] Another advantage is that the support of each lane 4 , 4 ′ on the legs 2 occurs only at two points, thus constituting an isostatic restraint that excludes the generation of stresses associated with restraint and deformation of the structure.

[0063] Another advantage is that the arrangement of the legs 4, 4' relative to the track 2 means that as the lift rises the two supports of each track 2 on the two legs 4, 4' become closer together, which reduces the inevitable bending deformation of the track under load when the lift is raised.

[0064] Another advantage is that the trend curve representing the pressure of the hydraulic fluid in the actuator 18 as a function of the lifting stroke of the carriageway 2 is decreasing, with all the beneficial effects in terms of stress on the actuator 18 and the control means, the mechanical safety of the raised lift always existing.

[0065] Another advantage is that there are no obstructions for the operator underneath the raised lift.

[0066] Another advantage is that, in the event of a seismic event, the elastic deformation of the buffer connection obtained between each leg 4, 4' and the track 2, by means of the rod 20, partially dissipates the energy applied to the lift.

[0067] Another advantage is that, when the lift is lowered, the legs 4, 4' are at a higher height at the articulation axis 10 at the respective base 8 than at the articulation axis 12 of the legs themselves at the track 2, which allows the use of the entire length of the legs 4, 4', so that legs of shorter length can be used, with the same overall dimensions of the lowered lift and the same maximum height that can be reached from the track 2. In particular, with the lift according to the invention, it is possible to obtain a ratio between the vertical lifting travel of the track 2 and the length of the legs 4, 4' (measured with reference to the articulation axis 10 and the articulation axis 12) that is close to or even greater than 1, unlike conventional lifts in which this value is significantly less than 1, the length of the leg being considered as the sum of the lengths of the two arms that form it, whether the lift's legs consist of a single arm or the lift's legs consist of articulated arms.

[0068] It should be noted that, when the lift is raised, differences in the loads affecting the support points of the lanes 2 at the legs 4, 4' are usually due to various reasons, such as, in particular, uneven distribution of weight in the vehicles raised, differences in the behavior of safety devices, deviations in the hydraulic power supply, differences in the pressure on the various jacks and consequently in the elongation of the jacks, deviations in the power supply, which tend to modify the geometry of the lift and to arrange the two lanes 2 in a different way, contrary to the reaction of the motor vehicle placed on the lanes in a braking state, which tends to exist to prevent the relative movement between them according to the lane axis.

[0069] If this tendency to change the geometry of the lift is kept below a certain level, related to the structural characteristics of the lift, it can be absorbed by the contact between the vehicle tires and the track, the deformability of the lift itself and the clearances. However, since, in practice, this tendency may exceed the absorption capacity of the deformability of the lift itself and the clearances, the invention envisages overcoming this tendency by adopting a shock-absorbing sleeve 26 which, in practice, allows to absorb, by its elastic deformation, the difference between the distance generated between the third articulation axis 22 rod / leg and the second articulation axis 12 leg / trolley and the distance between the third articulation axis 22 rod / leg and the fourth articulation axis 24 rod / track.

[0070] As an alternative to the shock absorbing sleeve, the present invention relates to the use of a rod 20' or 20" with a controlled variable length, such as Figure 6 Shown schematically.

[0071] exist Figure 72 shows in more detail an embodiment of a rod 20' with a controlled variable length. The rod 20' is provided with a circular opening 34 at one end for articulation to the lane 2 by connection with the fourth articulation axis 24, and a slide 36 is provided near the other end, which slides longitudinally along the rod 20' and is provided with a circular opening 38 for articulation to the legs 4, 4' by connection with the third articulation axis 22.

[0072] The slide 36 is placed between two preloaded compressed elastic contrast elements 40, which are themselves conventional and may consist of metal springs or air springs or hydraulic springs and which act on the slide itself in opposite directions so as to keep it elastically centered in its rest position but at the same time allow it limited movement in one direction or the other, depending on the tendency of the lane to assume different positions.

[0073] exist Figure 8 Another embodiment of a rod 20" with controlled variable length is shown in , which comprises two telescopic elements 42, 44 which can be articulated by their outer ends to the track 2 and to the legs 4, 4'. Between the inner circular base of the element 42 and a circular flange 43 fixed thereto by a connecting rod 46 axially movable relative to the element 42, a spring 48 is inserted which is preloaded in compression in an adjustable manner by means of a screw applied to the connecting rod itself.

[0074] If the rod 20" is subjected to a traction force, it will stretch as the two elements 42 and 44 slide against each other without generating any reaction force; and if the rod 20" is subjected to an axially compressive pressure, it will generate an elastic reaction force as the flange 43 associated with the element 42 rests against the support of the circumferential step formed in the inner wall of the element 44.

[0075] exist Fig. 9 Another embodiment of a rod 20'' is shown in the figure, which comprises an elongated central body 50, at the ends of which two connecting rods 52 are hinged, for hingedly connecting the rod 20'' to the track 2 via the fourth axis 24 and to the legs 4, 4' via the third axis 22. The central body 50 consists of two parts, which are connected together by a flat surface and are maintained in this state by compressing a preloaded spring 54. This rod 20'' works only by traction, in which case the spring 54 is further compressed, allowing the two parts of the central body 50 to temporarily keep a distance from each other. However, if the rod 20'' is compressed, it does not react to this type of stress, but is arranged so that the two connecting rods 52 form a certain angle relative to the central body 50.

[0076] Of course, the specific type of rod 20, 20', 20" or 20"' and its structural and functional characteristics are selected so as to allow it to have a bidirectional reaction force ( Figure 4 and Figure 7 ) or one-way reaction force ( Figure 8 and Fig. 9 ), which affects the number and position of the rods in the lift. In particular, if the rods are of the bidirectional type, such as rods 20, 20', they can be mounted on the same legs 4 and / or 4' of each lane 2, while if the rods are of the unidirectional type, such as rods 20", 20', they must be mounted on two legs 4, 4' of each lane 2.

[0077] exist Fig.10 , which uses a rigid rod 22 fixed to the legs and the track by shock absorbing bushings; however, as previously described, the same lift configuration can use a controlled variable length bidirectional rod 20' or a one-way rod 20" and 20"'.

[0078] Fig.11 The embodiment shown uses the same principles already described in the previous embodiments, differing from them essentially in that it has an actuator 30 which is not inserted between the legs 4, 4' and the respective base 8, but between the legs 4, 4' and the respective carriage 14 sliding along the track 2.

[0079] In addition to all the advantages already described in connection with the previous embodiments, this last embodiment has the further advantage that all the components of the lift, which for different reasons may be considered critical, namely the actuator 30, the mechanical, electrical and electronic control safety devices normally associated with the actuator 30, and the connections between these components and the power supply and the control unit, are situated in the upper part of the lift, which means that during use of the lift, the lift is kept at a distance from the floor, thus being better protected from the dirt (polluted material, washing liquids, etc.) which is normally present mainly on or near the floor.

Claims

1. A lift, in particular for motor vehicles, comprising at least one carriageway (2); two legs (4, 4') articulated to said at least one carriageway (2), each leg (4, 4') being made of a single arm; at least one actuator (30) associated with each leg (4, 4') and configured to vary the inclination of each leg (4, 4') relative to the horizontal plane, thereby raising and lowering said at least one carriageway (2); and a synchronization control unit for all actuators (30); characterized in that: - the two legs (4, 4') connected to the at least one track (2) are arranged symmetrically with respect to a transverse median plane of the lift, - the lower end of each leg (4, 4') is hinged to the base (8) by connection with a first fixed transverse axis (10) so as to be anchored to the floor, - the upper end of each leg (4, 4') is articulated to a trolley (14) by connection with a second transverse axis (12), said trolley (14) sliding along the corresponding track (2), - an additional connection is provided between at least one of the two legs (4, 4') of each track (2) and a track portion which, in the raised lift configuration, forms an angle of less than 90° with the leg (4), the additional connection comprising at least one rod (20, 20', 20", 20'"), one end of which is articulated to the leg (4) by connection with a third transverse axis (22) and the other end of which is articulated to the track (2) by connection with a fourth fixed transverse axis (24), - the at least one rod (20, 20', 20", 20'") is provided with elastic means configured to absorb variations in the distance between a third axis (22) of the rod itself articulated to the legs (4, 4') and a fourth axis (24) articulated to the at least one track (2), the variations in distance being caused by variations in the geometry of the lift due to load imbalances or in any case due to the functioning of the lift and being counteracted by the presence of a vehicle placed on the raised track.

2. The lift according to claim 1, characterized in that: In any lifting state of the lift, the distance between the upper ends of the legs (4) is smaller than the distance between the lower ends of the legs themselves.

3. The lift according to claim 1, characterized in that: In any lifting state of the lift, the distance between the upper ends of the legs (4) is greater than the distance between the lower ends of the legs themselves.

4. Lifting machine according to one or more of the preceding claims, characterized in that The distance between the third hinge axis (24) and the fourth hinge axis (26) is equal to the distance between the third hinge axis (24) and the second hinge axis (12).

5. Lifting machine according to one or more of the preceding claims, characterized in that The at least one rod (20) is substantially rigid and is articulated to the legs (4, 4') and / or the rail (2) via a damping sleeve (26).

6. The lift according to claim 5, characterized in that: The shock-absorbing sleeve (26) is made of elastic material and is placed between an internal pin integrated with the legs (4, 4') and / or the track (2) and a hollow cylinder integrated with the corresponding end of the rod (20).

7. Lifting machine according to one or more of the preceding claims, characterized in that The rods (20', 20", 20'") are of a controlled variable length type.

8. The lift according to claim 7, characterized in that: The rod (20') comprises: a main body, one end of which is provided with a device (34) for hingedly restraining to the lane (2) or the legs (4, 4'); a sliding member (36), which slides along the main body and is provided with a device (38) for hingedly restraining to the legs (4, 4') or the lane (2); and a preload elastic device (40), which cooperates with the sliding member (36) to generate a reaction force to its movement from a predetermined static position.

9. The lift according to claim 7, characterized in that: The rod (20") comprises two telescopic sliding elements (42, 44) between which an elastic device (48) is inserted, which is preloaded by compression and tends to react exclusively to the shortening deformation of the rod itself.

10. The elevator according to claim 7, characterized in that The rod (20'") comprises several parts (50, 52) articulated together and associated with elastic means (54) preloaded by compression, which keep the parts (50, 52) in a substantially aligned state.

11. Lifting machine according to one or more of claims 8 to 10, characterized in that The preload elastic device (40, 48, 54) is composed of a metal spring, an air spring or a hydraulic spring.

12. Lifting machine according to one or more of the preceding claims, characterized in that In the lowered lift configuration, the first articulation axis (10) connecting the legs (4, 4') to the base (8) is placed at a height not lower than the second articulation axis (12) connecting the legs (4, 4') to the carriage (14).

13. Lifting machine according to one or more of the preceding claims, characterized in that The at least one actuator (30) is placed between the legs (4, 4') and the relative base (8).

14. Lifting machine according to one or more of the preceding claims, characterized in that In the lowered lift configuration, the sixth articulation axis (32) of the actuator (20) connected to the relative leg (4, 4') is placed at a height not lower than the fifth articulation axis (28) of the actuator itself connected to the relative base (8).

15. Lifting machine according to one or more of the preceding claims, characterized in that The at least one actuator (30) is placed between each leg (4, 4') and a trolley (14) sliding along the corresponding track (2).

16. Lifting machine according to one or more of the preceding claims, characterized in that In the lowered elevator configuration, the at least one carriageway (2) houses therein a respective leg (4, 4'), an actuator (18) associated with the leg (4, 4'), the rod (20, 20', 20") and the base (8), the leg (4, 4') being articulated to the base (8).

17. Lifting machine according to one or more of the preceding claims, characterized in that The lift is configured so that the ratio of the maximum lifting stroke of the track (2) to the length of the legs (4, 4') is not less than 1, the maximum lifting stroke being measured with reference to the second articulated axis (12) connected to the corresponding trolley (14), and the length of the legs (4, 4') being measured between the second articulated axis (12) connected to the corresponding carriage (14) and the first articulated axis (10) connected to the corresponding base (8).

18. Lifting machine according to one or more of the preceding claims, characterized in that The elevator comprises a pair of rails (2), each rail being supported by two legs (4, 4').

19. Lifting machine according to one or more of the preceding claims, characterized in that Each lane (2) is configured so as to have a continuous longitudinal step (6) at least in correspondence with its inner longitudinal edge for supporting the inner crosspiece.

20. Lifting machine according to one or more of claims 1 to 17, characterized in that The lift comprises a single carriageway (2) to which a plurality of crosspieces are applied, which crosspieces project laterally from both sides of the carriageway itself and are configured to support motor vehicles.

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