Field of the invention

The present invention relates to a front suspension system, in particular of an industrial vehicle comprising two front axle s .

Description of the prior art

Heavy-duty industrial vehicles are provided with two front axles, both steering.

Usually the second is connected to the chassis through a dedicated suspension in order to bear higher load.

However, an uneven load distribution can arise with a poor drivability of the vehicle. Other negative effects are a poor braking action and an uneven tyre wear.

Summary of the invention

The main aim of the present invention to provide a suspension scheme implemented for both the front axle capable to improve the drivability of the vehicle and to reduce the above problems/drawbacks.

The main principle of the invention is to combine air bellows with guided spring leafs.

In addition, the air bellows are controlled in order to evenly distribute the load between both the two front axles .

A first object of the present invention is a front suspension system for a two front axle industrial vehicle. Another object of the present invention is a vehicle comprising such front suspension system.

Advantageously, the present invention, not only permits to better distribute the load and consequently the wear of the tyre on both the front axles, but, in case the vehicle is capable to control the height of the chassis, being the two front axles suspensions identical between each other, also the height control is easiest in view of the fact that the geometries of the suspension do not introduce uneven distribution of load with the height variation.

Analogously, also the stiffness variation of the bellows reaction does not introduce uneven distribution of load. The attached claims describe preferred embodiments of the invention, forming an integral part of the present description .

Brief description of the drawings

The invention will become fully clear from the following detailed description, given by way of a mere exemplifying and non limiting example, to be read with reference to the attached executive drawing figures, wherein :

- Fig. 1 shows a side view of the front suspension system,

- Fig. 2 shows a top view of the front suspension system of figure 1;

- Fig. 3 shows a perspective view of the front suspension system of figure 1.

The same reference numerals and letters in the figures designate the same or functionally equivalent parts.

According to the present invention, the term "second element" does not imply the presence of a "first element", first, second, etc.. are used only for improving the clarity of the description and they should not be interpreted in a limiting way.

Detailed description of the preferred embodiments

Figure 1 discloses a front suspension system according to the present invention.

The suspension system comprises two front axles A and B anchored to the side members SM defining the chassis of the industrial vehicle.

Both axles are steering, even if they could assume different steering angles: usually the second axle assume a relative reduced steering angle in comparison with the first one.

The ends of the side members SM depicted on the left side of figures 1 - 3 are shaped to support an internal combustion engine and a cab where a dashboard and controls are arranged. Thus, the axle A is the first front axle and the axle B is the second one arranged just behind the axle A.

The suspension system comprises, for each side of the vehicle, two leaf springs LSA and LSB arranged longitudinally, namely substantially parallel to the side member, one for each axle A and B.

The first leaf spring LSA is anchored, at its opposite ends, to the side member SM by means of a first support FS and a second support SS.

A first swinging arm SAA, having an elongated shape, has a first end hinged to the first support FS and a second end fixedly connected with an intermediate region of the first leaf spring LSA and with one end of the first axle A. Therefore, the first support defines a coaxial hinge for both the first leaf spring and its swinging arm. The bellow ABA is arranged between the leaf spring and its corresponding side member, in order to control the relative approaching/removal movement of the axle A with respect to the vehicle chassis. Preferably, said fixed connection is realized by means of strips STP per se known in order to pack together axles and leaf springs .

The second support SS defines two parallel hinges: one to support a second end of the first leaf spring LSA and another to support a first end of the second leaf spring LSB and its corresponding second swinging arm SAB. The construction of the second suspension is substantially identical to the first one.

A third support TS connect the second end of the second leaf spring LSB by defining a further hinge.

All the hinges have axes perpendicular to the longitudinal development of the side members.

The second end of the first swinging arm SAA is also connected to the side member SM though a first bellow ABA interposed between said end and the side member. Analogously the second arm of the second swinging arm SAB is also connected to the side member SM though a second bellow ABB interposed between said end and the side member. According to figure 3, it is clear that the side member diverge between each other in order to offer a larger room to the combustion engine.

Therefore, the first support FS is connected to the side member internally, namely the face of the side member oriented toward the other side member. The second SS support element is perfectly under the side member, while the third TS support element is connected to the external face of the side member.

According to a preferred embodiment of the invention, the bellows are air bellow or hydro-pneumatic bellow.

Preferably, the bellows are directly connected to corresponding swinging arms SAA, SAB, namely without any carriers .

Anyway, it is preferred the implementation of an automated load distribution between the axles A and B as the load distribution means usually adopted in the rear axles of the industrial vehicles.

Preferably, the second axle B is of the driving type, and first axle A is of the driven type therefore, in the figures a differential arrangement is disclosed to distribute torque over the wheels.

According to another configuration, both the axles are of the driving type, thus both are provided of a central differential to receive propulsion by the internal combustion engine of the like through a transmission shaft. However, other configuration can be foresee, for example the first axle A could be provided of hydraulic engine in the hubs, while the second axle B could be driven by the internal combustion engine through a transmission shaft. Preferably, in order to avoid any collisions between the axles and the side members, bumper BP are connected on the side members, protruding downwards, comprising resilient elements arranged in order to stop the second ends of the swinging arms SAA and SAB while approaching the chassis. Many changes, modifications, variations and other uses and applications of the subject invention will become apparent to those skilled in the art after considering the specification and the accompanying drawings, which disclose preferred embodiments thereof. All such changes, modifications, variations and other uses and applications do not depart from the scope of the invention are deemed to be covered by this invention.

It should be understood that all the single features and/or embodiments can be combined between each other. In addition, the features disclosed in the prior art background are introduced only in order to better understand the invention and not as a declaration about the existence of known prior art. Therefore, also the features described in the prior art background can be considered in combination with those mentioned in each embodiment of the detailed description.

Further implementation details will not be described, as the man skilled in the art is able to carry out the invention starting from the teaching of the above description .