Patent Description:
A traditional rigid axle arrangement with hydraulic suspension generally comprises a main connecting axle of at least one pair of driven wheels, coupled directly to the vehicle frame by means of one or more typically longitudinal connecting arms, one or more hydraulic suspension cylinders and a cross bar reacting to transverse loads.

The hydraulic suspension is one of the mostly widespread suspensions on agricultural towed machines instead of the traditional mechanical leaf spring suspension.

A hydraulic suspension allows a homogeneous distribution of the weight of the vehicle on the wheels and therefore an optimal grip even in the presence of dynamic loads, because the hydraulic circuit keeps all the actuators at the same pressure.

A hydraulic suspension also allows to intervene on the travel height of the vehicle by acting on the volume of fluid in the actuators.

Finally, a hydraulic suspension optimizes the travel behaviour/comfort by coupling one or more elastic elements, such as inert gas accumulators, to the rigid hydraulic circuit.

Among other things, advantageously, the hydraulic supply system is now a standard feature for all tractors.

A type of hydraulic suspension is known where the upper end of the hydraulic suspension cylinder is fixed laterally to the load-bearing frame of the trailer while the lower end is connected below the axle on the forward side.

Another type of hydraulic suspension is also known where the upper end of the hydraulic suspension cylinder is fixed laterally to the load-bearing frame of the trailer in a higher position than the plane of the main body of the trailer, and the lower end is connected above the axle on the forward side.

There are also state-of-the-art solutions in which the hydraulic suspension has the hydraulic suspension cylinder arranged coplanarly under the side member of the load-bearing frame of the trailer, so that, with the same dimensions of the wheels and of the track with respect to the solutions previously described, it is possible to increase the spacing between the side member of the load-bearing frame of the trailer, because the hydraulic suspension cylinder is not interposed transversely between the driven wheel and the side member.

The latter solution benefits the torsional stiffness of the frame and does not apply any local twisting to the side members.

<CIT> teaches an oil-hydraulic suspension for connecting a chassis to an axle of a vehicle, <CIT> shows an axle arrangement for an agricultural baler.

One of the main drawbacks complained about by the trailer manufacturers in a vehicle and referred to the axles, typically to the axles with known hydraulic suspensions, consists in the fact that they are supplied as a set of components that must be assembled and fixed to the frame of the trailer. Each component must be coupled respecting the design geometries, and fixed with the appropriate and different fixing means characteristic of the various components to the frame of the trailer, generally consisting of longitudinal side members.

From a logistical and operational point of view, this leads to assembly complications that can significantly lengthen the times for setting up the axle on the trailer of the vehicle.

The technical task addressed by the present invention is accordingly to realise a rigid axle arrangement with hydraulic suspension for a trailer of a vehicle that enables the decried technical drawbacks of the prior art to be eliminated.

Within the scope of this technical task an object of the invention is to realise a rigid axle arrangement with hydraulic suspension for the trailer of a vehicle that can be set up on the frame of the trailer in a simple and fast way.

The technical task, as well as these and other purposes, according to the present invention are achieved by realising a rigid axle arrangement according to claim <NUM>.

Preferred embodiments of the invention are defined in the dependent claims <NUM>-<NUM>.

An independent module fixable to a frame of a trailer of a vehicle is also described, comprising a load-bearing frame, a rigid axle comprising at least one front connecting arm, a hydraulic suspension comprising at least a pair of right and left hydraulic cylinders of suspension, and at least one cross bar contrasting axial transverse loads acting on said rigid axle, wherein said rigid axle is connected by said at least one front connecting arm, at least said pair of right and left hydraulic cylinders and said cross bar directly to said load-bearing frame of said independent module.

A load-bearing frame is also described, comprising a right longitudinal plate and a left longitudinal plate that are rigidly connected at the front by a cross bar, said right longitudinal plate and said left longitudinal plate being directly fixable to the frame of said trailer.

Further characteristics and advantages of the invention will more fully emerge from the description of a preferred but not exclusive embodiment of a rigid axle arrangement with hydraulic suspension for a trailer of a vehicle according to the invention, illustrated by way of non-limiting example in the accompanying figures of the drawings, in which:.

With reference to the aforementioned figures, a rigid axle arrangement with hydraulic suspension for a trailer of a vehicle is shown, as a whole indicated with the number <NUM>.

The trailer is towed in the direction T, corresponding to the longitudinal axis X of the trailer.

The rigid axle arrangement <NUM> comprises at least one rigid connecting axle <NUM> of at least one pair of driven wheels, not shown for simplicity of the drawing, mounted on the hubs <NUM> A and <NUM> B. The rigid axle arrangement <NUM> comprises a hydraulic suspension <NUM> comprising at least one pair of hydraulic suspension cylinders, right cylinder <NUM> and left cylinder <NUM>, and at least one cross bar <NUM> contrasting axial transverse loads acting on the rigid axle <NUM> in operation.

The rigid connecting axle <NUM> has at least one front connecting arm <NUM>.

Innovatively and advantageously, according to the present invention, such at least one arm <NUM>, such at least one pair of right <NUM> and left <NUM> suspension hydraulic cylinders and such at least one contrasting cross bar <NUM> are fixed to a load-bearing frame <NUM> of an independent module <NUM>, fixable to the frame of the trailer, typically to the longitudinal side members of such a trailer.

The load-bearing frame <NUM> comprises a right longitudinal plate <NUM> and a left longitudinal plate <NUM> that are rigidly connected at the front by a cross member <NUM>.

The right longitudinal plate <NUM> and the left longitudinal plate <NUM> are directly fixable to the longitudinal side members of the frame of the trailer, by means of known connecting means, not shown in the drawings, typically fixing bolts or welding points.

The right <NUM> and left <NUM> longitudinal plates are typically parallel to one another, and parallel to the longitudinal axis X of the trailer and orthogonal to the rigid connecting axle <NUM>. Advantageously, the cross member <NUM> has in the centre, on the longitudinal axis X of the trailer, a central spherical joint <NUM> to which the front connecting arm <NUM> of the rigid connecting axle <NUM> is connected.

Suitably, in fact, according to the present invention, the arm <NUM> comprises a triangular structure hinged to the cross member <NUM> by the ball joint <NUM> and an opposite side <NUM> rigidly connected to the rigid connecting axle <NUM>.

The right <NUM> and left <NUM> hydraulic cylinders of the suspension have an upper end <NUM> and <NUM> hinged respectively to the right longitudinal plate <NUM> and to the left longitudinal plate <NUM>, and a lower end <NUM> and <NUM> hinged to the rigid connecting axle <NUM> near the wheel hubs <NUM> A and <NUM> B.

Typically, the lower ends <NUM> and <NUM> of the hydraulic cylinders <NUM> and <NUM> are hinged below and in front of the rigid connecting axle <NUM>.

Typically, the lower ends <NUM> and <NUM> and the upper ends <NUM> and <NUM> of the hydraulic cylinders <NUM> and <NUM> are hinged with orthogonal hinge axes: the hinge axis of the lower ends <NUM> and <NUM> is parallel to the rigid connecting axle <NUM> and the hinge axis of the upper ends <NUM> and <NUM> is parallel to the longitudinal axis X of the trailer, parallel to the axis of the longitudinal plates <NUM> and <NUM>.

The cross bar <NUM> connects the rigid axle <NUM> to the load-bearing frame <NUM>: the cross bar <NUM> has in fact an upper end <NUM> hinged to one of the right <NUM> and left <NUM> longitudinal plates, and a lower end <NUM> hinged to the rigid connecting axle <NUM> in an opposite position, typically symmetrical, with respect to the longitudinal axis X.

The cross bar <NUM> is typically positioned behind the rigid connecting axle <NUM>, and is hinged to one of the longitudinal plates <NUM> or <NUM> behind the hinge point of a cylinder <NUM> or <NUM> to said longitudinal plate <NUM> or <NUM>.

With reference to the figures, the present invention therefore shows a rigid axle <NUM> with hydraulic suspension <NUM> for a trailer of a vehicle, comprising an independent module <NUM> fixable to a frame of a trailer of a vehicle.

Said independent module <NUM> comprises a load-bearing frame <NUM>, a rigid connecting axle <NUM> comprising a front connecting arm <NUM>, a hydraulic suspension <NUM> comprising at least one pair of right and left hydraulic suspension cylinders <NUM> and <NUM> and at least one cross bar <NUM> contrasting axial transverse loads acting on the rigid connecting axle <NUM>.

Advantageously, according to the present invention, the rigid connecting axle <NUM> is connected by the front connecting arm <NUM>, the pair of right <NUM> and left <NUM> hydraulic cylinders, and the cross bar <NUM> directly to the load-bearing frame <NUM> of the independent module <NUM>: the independent module <NUM> thus configured is therefore directly fixable to the frame of the trailer by the right longitudinal plate <NUM> and the left longitudinal plate <NUM> of the load-bearing frame <NUM>.

The operation of a rigid axle arrangement with hydraulic suspension for a trailer of a vehicle according to the invention is clear from what is described and illustrated and, in particular, is substantially as follows.

The components of the rigid axle with hydraulic suspension, indicatively but not limited to the load-bearing frame <NUM>, the rigid connecting axle <NUM>, the connecting arm <NUM>, the pair of right <NUM> and left <NUM> hydraulic cylinders and the cross bar <NUM> are produced and/or assembled by the manufacturer of the rigid axle.

The rigid connecting axle <NUM> with the connecting arm <NUM>, the pair of right <NUM> and left <NUM> hydraulic cylinders and the cross bar <NUM> are then connected to each other and with the drawing geometries to the load-bearing frame <NUM>.

The independent module <NUM>, consisting of the load-bearing frame <NUM> so suitably equipped, is supplied to the manufacturer of the trailer, who fixes it to the frame in a predetermined design position by means of simple known coupling means, typically bolts and/or welding points, between only the right longitudinal plate <NUM> and the left longitudinal plate <NUM> and the longitudinal side members of the trailer.

In practice, it has been found that a rigid axle with hydraulic suspension <NUM> for a trailer of a vehicle according to the invention is particularly advantageous such as to be able to be set up on the frame of the trailer in a simple and fast way.

The rigid axle arrangement with hydraulic suspension for vehicles thus conceived is susceptible to numerous modifications and variations, however, the invention is defined in the claims.

Claim 1:
A rigid axle arrangement (<NUM>) with hydraulic suspension (<NUM>) for a trailer of a vehicle, comprising at least one rigid connecting axle (<NUM>) of at least one pair of driven wheels, at least one front connecting arm (<NUM>) of said rigid connecting axle (<NUM>), at least one pair of right (<NUM>) and left (<NUM>) hydraulic suspension cylinders, and at least one cross bar (<NUM>) reacting to the axial transverse loads acting on said rigid connecting axle (<NUM>), characterised in that said at least one arm (<NUM>), said at least one pair of hydraulic suspension cylinders (<NUM>, <NUM>) and said at least one cross bar (<NUM>) are reciprocally fixed to said rigid connecting axle (<NUM>) and to a load-bearing frame (<NUM>) fixable to the frame of said trailer, said load-bearing frame (<NUM>) comprising a right longitudinal plate (<NUM>) and a left longitudinal plate (<NUM>) that are rigidly connected at the front by a cross member (<NUM>), said right longitudinal plate (<NUM>) and said left longitudinal plate (<NUM>) being directly fixable to the frame of said trailer, said cross member (<NUM>) having a central spherical joint (<NUM>) to which said at least one arm (<NUM>) is connected, said arm (<NUM>) comprises a triangular structure hinged to said cross member (<NUM>) by said spherical joint (<NUM>) and an opposite side (<NUM>) rigidly connected to said rigid connecting axle (<NUM>).