FR2824021A1 - Center lifting axle has spring plate positioned on corresponding end of axle so that free end of spring fastened to spring plate is located in required position for fastening spring to hanger on vehicle - Google Patents

Abstract

A spring plate (2) is positioned on a corresponding end of the center lifting axle so that the free end of a spring which is fastened to the spring plate is located in the required position for fastening the spring to a hanger on the vehicle. Additionally, means in the form of U-bolts (7) are provided to exert a pressure on the spring plate to keep it in the required position on the lifting axle, and means are provided to secure the spring plate on the axle. Independent claims are included for a front hanger for a spring of a center lifting axle, and for a procedure for the manufacture of a center lifting axle.

Description

(16). The present invention relates to suspension systems for

  road vehicles, and in particular, but not necessarily exclusively, relates to suspensions for tractor, semi-trailer or carrier vehicles of the type in which at least one axle can be raised in order to isolate its wheels from the ground. In the design of towing, semi-trailer or carrier vehicles, careful consideration must be given to local and current legislation defining the maximum authorized axle loads, more reality than in some countries, if the axle loads are defined at o lower levels, tax advantages are granted to

  vehicle owner / user.

  We must also remember that, while it is advantageous to maximize the load on a commercial vehicle, there are a number of occasions when the circumstances are such that a vehicle has a load lower than the maximum allowed , and can even run empty, for example during the return journey after delivery of a load. Maintaining a higher number of wheels in contact with the ground than required by loading below the maximum required, or by an empty vehicle, generates increased operating costs by increasing fuel consumption per unit o of course, and unnecessary wear of tires and auxiliary equipment associated with wheels such as brake pads and discs or drums

of brake.

  We have therefore known for a long time the principle of having at least one axle on a tractor or semi-trailer vehicle with several axles capable of being raised, to isolate its wheels from the ground at times such as when the vehicle is running idle, or that its loading requires less than all of the axles provided to support part of the vehicle's loading and maintain the axle load at a level equal to or below the authorized levels. o Such lifting axles are generally designated central axles, and are frequently mounted as accessories on vehicles

  tractors, semi-trailers or carriers after their construction.

  The subsequent mounting of central axles poses many difficulties.

  Normally, a spring seat is attached to the top dead center of an axle towards each of its outer ends, the spring seat having been machined with a groove to receive the end of the spring. The seat is welded to the axle}

  and, as a result, the longitudinal alignment of its spring cannot be ensured.

  Similarly, and in particular with the central axles for tractor or carrier vehicles, they are forged to provide a central U-shaped section in order to allow the axle to be released from the vehicle's drive shaft. Axle forging can cause axial misalignment as between one end and the other, adding to the possibility of longitudinal misalignment of the spring groove in the spring seat. In addition to this, the leaf springs themselves may have lateral distortion between the end fitting the spring seat and an eye at the opposite end to fit a suspension mount strategically attached to the vehicle to

  a required distance from the position of the central axles.

  The overall result of these aforementioned possibilities is that in a relatively large proportion of cases, once the central axle has been presented and fixed to the vehicle, the eye of the spring is appreciably distant from the centering position of the front suspension, and considerable force is required to bring the end of the spring into alignment with the front suspension, and once fixed in position, considerable stresses are induced in the suspension system, which deteriorates the effectiveness of the

  suspension of the central axle, and can lead to premature failure.

  o The object of the present invention is to provide a central axle for a tractor, semi-trailer or carrier vehicle which remedies the

  disadvantages relating to the above.

  According to a first aspect of the present invention, a central axle for a tractor, semi-trailer or carrier vehicle comprises a spring seat placed on a respective end of the central axle so that a spring placed on the seat spring at its free end in a position required to be attached to a suspension on a vehicle, means for applying pressure to the spring seat to assist in maintaining it in the required position on the central axle and means to fix the spring seat to the axle. Preferably, the means for applying the pressure consists of two U-shaped bolts placed on either side of the spring seat and extending around the axle from a connection plate extending above the spring seat. The means for fixing the spring seat to the central axle can be an elastic resin connecting material interposed between the spring seat and the central axle. Alternatively, the means for fixing the seat to the central axle is a weld using a filler material

  compatible between the edge of the seat and the central axle.

  The spring seat may have, on its upper surface, concurrent flanges on each side, to provide a space for receiving the end of a leaf spring, and preferably the connecting plate covers the end of the spring. with blades. Advantageously, the distance between the spring seat between the vertical flanges is greater than the width of the end of the spring, and adjustable locking elements extend through

  the flanges to come into abutment against the side walls of the leaf spring.

  o This completely avoids the need to practice spring grooves in

the spring seats.

  When used, the elastic resin can be a two-component epoxy resin suitable for fixing, and which can retain its elasticity for several years. It will be understood that care must be taken in the application of the resin on the axle, and of the spring seat on the resin, with adequate pretreatments of the two to ensure that they are clean and free of grease before their contact. with the resin. The use of an elastic resin to bind the spring seat to the axle, plus the action of the U-bolts. Provides a substantial guarantee of the maintenance of the spring seat without displacement on the axle, in all conditions load, and the flexible nature of the resin is such that it ensures the absorption of all lateral impacts on the vehicle wheels without breaking the resin interface

  between the spring seat and the axle.

  When mounting the axle and its springs, the U-bolts are left:, loose, and the locking elements on the spring seat are retracted, to allow the end of the spring to be slid under the plate locking, the axle is then presented to a jig to prevent it from moving, and to allow the free end of the spring to be placed in the position required for its subsequent fixing to a suspension on the vehicle. Consequently, and independently of any misalignment of the axle during its forging and of any distortion of the spring, the spring assumes a correct position on the seat, after which the fastening elements are brought inwards to come into contact with the sides of the spring and the U-bolts tightened to lock the spring seat and consequently the spring in position on the axle. If resin is used, it associates with the U-bolts to ensure that the spring seat retains its position. Alternatively, and after tightening the U-bolts, the front edge and possibly the rear edge of the seat can be welded to the central axle, but the quantity of filler metal required is such that the welding step cannot not

  distort the axle or the position of the seat placed on it.

  The axle and the spring can then be presented to a vehicle with the certainty that the free end of the spring will be correctly positioned, and the drawbacks of prior art constructions will be

substantially avoided.

  While the first aspect of the invention gives the certainty of a precise positioning of the spring seats and therefore of the springs on the axle, there is the possibility for the suspension before being formed and fixed to the chassis of the vehicle. so that the positioning point for the front end of the spring is not square, which makes it difficult to position the eye on the suspension using a pivot axis, as required the

central axles.

  According to a second aspect of the invention, a front suspension for a leaf spring of a central axle comprises a means of connection to the chassis of the vehicle and a means of pivoting connection of the end of a leaf spring, the means connecting the end of a leaf spring comprising a component in a square with side walls, said side walls being diverging towards the outside towards the open end of the bracket, so as to receive the spring and with also a means of fixing a pivot axis on the free end of the spring to the suspension bracket. In one form of construction, there may be pivot holes in the side walls: 5 of a diameter larger than the diameter of a pivot axis intended to keep an eye of the spring in the square. Alternatively, the spring end may extend beyond the suspension, and bolts are provided to pass through the bolt holes in the pivot axis and engage

  threaded holes in the face of the suspension.

  o As a result of the manufacture of the front suspension, if its connection to the chassis of the vehicle has the effect of placing the bracket in misalignment relative to the eye of a spring to be presented to it, the divergent or flared arrangement of the walls of the bracket allows the insertion of the spring, and either the oversized holes allowing the introduction of the pivot axis, followed by the walls of the bracket being clamped against the sides of the spring eye, or the axis pivot bolted to the suspension to stop any lateral movement of the spring, however allow a pivoting movement of the spring by

compared to the square.

  As mentioned above, conventional central axles are forged to ensure that the drive shaft of a tractor or carrier vehicle is not

s not dirty.

  In its first and second aspects, the invention substantially eliminates these problems of attachment to vehicles which have been historically the case, but the deformation of the axle can be such that not only the misalignment of the spring is a serious problem, but also of the

  o Problems related to the attachment of the axle to the vehicle may occur.

  According to a third aspect of the present invention, a central axle comprises a straight beam, vertical support elements at each end of the beam, each support element having a stub axle

extending outward.

  Preferably, the straight beam is a hollow tube-shaped beam, to provide high strength and low weight, and the vertical support elements are prefabricated construction elements which allow the precise orientation of the respective knuckle, at the ends of the beam, to help with the accuracy of the positioning of the spring seats and

springs.

  In the description above, reference is made to positioning

  a spring on the spring seat. However, it will be fully understood that the invention also applies to the positioning of a support arm between the central axle and the front suspension, for an airbag of a system of

s airbag suspension.

  We have not described above the manner in which the central axle is fixed to the vehicle, and the means by which the wheels of the central axle can be raised and lowered to be put respectively out of contact or in contact with the soil when desired. Conventional fixing means and lifting and lowering means can be used, such as

  will fully understand those skilled in the art.

  Five embodiments of the invention are described below in reference to the appended drawing, in which: FIG. 1 is a perspective view of a spring seat and of a spring according to the first aspect of the invention; Figure 2 is a perspective view of a suspension according to the second aspect of the invention; Figure 3 corresponds to Figure 1 but shows a third embodiment of the invention; FIG. 4 corresponds to FIG. 2 but shows a fourth embodiment of the invention; and Figure 5 is a vertical sectional view of a straight beam according to the third aspect of the invention, on which are mounted spring seats

  and springs as in Figure 1.

  o Figures 1 to 4 use identical reference numerals for the

identical pieces.

  In FIG. 1, a central axle 1 for a vehicle, intended to be fitted as a retrofit on the vehicle, carries a spring seat 2 placed so that a spring 3 adapted above has its eye 4 correctly positioned relative to to the axle, so that when the axle is mounted on a vehicle, the eye is in the correct position to be fixed to a suspension attached to the chassis of the vehicle. The spring seat has vertical flanges 5 to make a space in which the spring is mounted and a connecting plate 6 covers the spring, and U-bolts 7 engage around the axle and are fixed to the plate bond to apply pressure on the

  spring and seat, in order to participate in its solid fixing on the axle.

  In the embodiment of Figure 1, a two-component epoxy resin of a nature to be suitably attached as an adhesive and capable of retaining its elasticity for many years is

  interposed between the spring seat and the axle.

  To position the spring seat 2 and the spring 3, a template (not shown) can be provided, having a recess to accept the axle, and recesses to receive the bases of the U-bolts. The template also has a piece of fixing for ocil 4 of the spring. Thus, with the U-shaped bolts o positioned in the groove and the axle placed in the recess, the spring seat can be positioned on the axle at a necessary distance from one end, the spring 3 mounted in space between the flanges 5, the plate

  connection 6 in place and U-bolts 7 tightened by hand.

  As shown in FIG. 1, the flanges 5 have positioning studs in screwed engagement with the tapped holes in the flanges, left loose on the outside, and tightened in contact with the spring once

  mounted in the space between the flanges.

  The spring eye 4 is then subject to fixing on the template, to adjust the alignment of the spring, and place the seat 2 on the axle 1 in its required position. By applying epoxy resin between the seat and the axle, and tightening the U-bolts to apply pressure by means of the connecting plate 6 on the spring and the spring seat, a more secure fixing of the spring to the the axle is made with the spring and the spring eye in the position required to give considerable assistance in attaching the spring eye to a suspension on the vehicle chassis when the central axle is

  retrofitted on a vehicle.

  Even with the fixing of a spring and a spring seat on an axle as described above, a dogré of misalignment of the spring and therefore of the position of its eye can be encountered, possibly caused by a slight imprecision in mounting a suspension on a vehicle. Consequently, as shown in FIG. 2, a suspension 8 has flanges 9 for attachment to a vehicle chassis, the arm 10 carrying the flanges having a bracket 11 with divergent side walls 12 in a downward direction, the walls 12 having through holes 13 for a pivot axis o. Thus, with the axle 1 and the suspension 8 mounted on a vehicle, the spring eye 4 can be presented at the square 11, whose divergent walls 12 relatively facilitate the positioning of the spring eye so that 'a pivot axis can be introduced into the holes 13 and

in the spring eye.

  s In FIGS. 3 and 4, a substantially identical spring and suspension assembly are respectively represented. In FIG. 3, the assembly of spring seat 2, spring 3, connection plate 6 and U-bolts 7 is fixed to an axle in a manner essentially similar to that described in connection with FIG. 1. Here, and for help even more in the correct positioning of the

  o spring and seat, the spring is fixed to the seat by a rear pivot pin 14.

  In Figure 3, and in place of an epoxy resin between the spring seat 2 and the axle, the seat, after tightening the U-bolts 7 to fix the assembly to the axle, is welded by its edge front 15 to the axle, and if desired, is additionally welded by its rear edge. The degree of welding required to complete the fixing of the assembly and to ensure that the spring seat does not move in use is not sufficient to cause distortion

  any of the spring seat axle.

  In place of an eye at the end of the spring, Figure 3 shows a pivot bar 16 with bolt holes 17. In Figure 4, an alternative embodiment of the suspension 8 is shown with a plate 8A for attachment to the side of a vehicle chassis. Here, the underside of the suspension has an integral square formed by divergent walls 18, the suspended walls of bosses 19 having bolt holes 20. Here again, the use of divergent walls facilitates the positioning of the spring in the square, but with the end of the spring protruding beyond the bracket to allow its fixing by bolts passing through the bolt holes in the axis and in the bolt holes in

the bosses.

  To avoid all the above-mentioned problems with forged axles, FIG. 5 shows a form of construction in which the axle is formed by a straight beam 21, the beam towards each of its ends being equipped with sets of springs as described above. with reference to FIG. 1 or to FIG. 3. At the outer ends of the beam, vertical support elements 22 are provided on which spindle carriers 23 for wheels on the ground are to be fixed, in order to offset the horizontal axes of the carriers fusoes and beam, to allow the release of the beam like a knuckle turning under the vehicle without having to forge or deform the beam itself.

Claims (13)

  1. Central axle for a tractor, semi-trailer or carrier vehicle characterized by a spring seat (2) placed on a respective end of the central axle (1) such that a spring (3) mounted on the spring seat at its free end in a position required to be attached to a suspension (8) on the vehicle, means (7) for applying pressure to the spring seat to assist in holding it in position required on the axle   central and means for fixing the spring seat on the axis.   2. Central axle according to claim 1, characterized in that the pressure applying means consists of two U-bolts (7) placed on each side of the spring seat and extending around the axle (1 ) from   a connecting plate (6) extending above the spring seat (2).   3. Central axle according to claim 1 or claim 2, characterized in that the means for fixing the spring seat (2) to the central axle (1) is an elastic resin connecting material interposed between the   spring seat (2) and the central axle (1).   4. Central axle according to claim 1 or claim 2, characterized in that the means for fixing the seat to the central axle is a weld using a compatible filler material between the seat edge ( 15) and the central axle (1).   5. Central axle according to any one of claims 1 to 4,   characterized in that the spring seat (2) has, on its upper surface, concurrent vertical flanges (5) on each side, to create a space   to receive the end of a leaf spring (3).   6. Central axle according to any one of claims 1 to 5,   o characterized in that the connecting plate (6) covers the end of the leaf spring. 7. Central axle according to claim 5 or claim 6, characterized in that the distance through the spring seat (2) between the vertical flanges (5) is greater than the width of the end of the spring, and adjustable locking elements extend through the flanges for   come to bear against the side walls of the leaf spring.   s 8. Front suspension for a leaf spring of a central axle, characterized by a connection means (8A) to the vehicle chassis and a pivoting connection means from the end of a leaf spring (3), the means connecting the end of a leaf spring comprising a square component with side walls (12, 18), said side walls being diverging towards the outside towards the open end of the bracket (8), to receive the spring and means being present for fixing a pivot pin (16) on the end   free from the spring (3) to the suspension bracket (8).   9. Front suspension according to claim 8, characterized in that there are pivot holes (13) in the side walls (12) of a diameter larger than the diameter of a pivot axis intended to maintain   an eye (4) of the spring in the square.   10. Front suspension according to claim 8, characterized in that o the spring end extends beyond the suspension, bolts passing through the bolt holes (17) in a pivot axis (16) and   engaging tapped holes (20) in the face of the suspension.   11. Central axle characterized by a straight beam (21), s vertical support elements (22) at each end of the beam, each   support element having a stub axle (23) extending outwards.   12. Central axle according to claim 11, characterized by the presence of spring seats (2) and springs (3) as defined above in a   any of claims 1 to 7.   13. Method of constructing a central axle according to any one   of claims 1 to 7, characterized in that on the mounting of   the axle (1, 21) and its springs (3), the U-bolts (7) are left 3s loose, and the locking elements on the spring seat are retracted, to allow the end of the spring d being slid under the locking plate (6), the axle is then presented to a jig to prevent it from moving, and allowing the free end of the spring to be placed in the position required for its subsequent fixing to a suspension (8) on the vehicle so that the spring takes a correct position on the seat, after which the fasteners are brought inwardly to come into contact with the sides of the spring and the U-bolts tightened to block the spring seat and