Patent Description:
The prior art will be described below with particular reference to the field of railway vehicles. The above may be applied similarly, where possible, also to vehicles of other fields traveling by rail.

After the activation of a railway vehicle or a railway convoy including several railway vehicles, before its entry into service, for example daily operation, an action known to those skilled in the art as a "brake test" is carried out. This action is necessary to verify the correct operation of a braking system, as a whole of the railway vehicle or a railway convoy.

The "brake test" is performed with different methods depending on the composition of the type of one or more railway vehicles and the composition of the railway convoy.

In the case of latest generation railway convoys, known as fixed composition, the brake test is generally automated. For example, by means of pressure sensors connected to braking cylinders of a braking system, the braking control means (e.g. computer) check that the pneumatic braking pressures controlled by them are actually present at said braking cylinders, within predetermined tolerance bands.

However, this type of automatic check is not able to verify that the braking cylinder of the braking system applies the braking force, corresponding to the braking pressure, to a pad-disc or shoe-wheel clutch pair. Malfunctions of the braking cylinder may for example vary the nominal pressure/force ratio by locally reducing the braking force.

In the case of freight convoys, made for example by a locomotive and a plurality of railway vehicles, there is no information means of communication between said locomotive and the connected railway vehicles. In this case, the "brake test" includes a procedure which involves an operator, who is asked to check, at least visually, that in the absence of pneumatic braking pressure the shoe <NUM> is detached from the wheel, or that the pad is detached from the disc. The operator should also check that in the presence of pneumatic braking pressure, the shoe is in contact with the wheel, or the pad is in contact with the disc.

This procedure requires an extremely long time, as for the visual verification the operator is forced to walk along the railway vehicle or railway convoy on each side, in all its length. This procedure is carried out in the case of applied braking and then repeated in the case of released braking. Furthermore, the visual analysis does not ensure that, when visually the braking is applied, the pressure actually applied to the braking cylinders corresponds to the nominal one, concealing hidden faults to one or more pneumatic components in the braking force generation chain.

The problem relating to the "brake test" was previously described with reference to pneumatic braking systems. However, the same problem may be found likewise in electro-pneumatic or electromechanical braking systems and in the related braking application means.

Recent technological developments propose to provide each railway vehicle with a self-powered data acquisition system through "energy harvesting" systems, connected to appropriate pressure and force sensors, provided with wireless communication means, and capable of transmitting to the ground data related to the brake test during the "brake test" step.

As much as the proposed system works, it implies a high cost both in terms of hardware components and in terms of installation and upgrade costs for the complete fleet.

Furthermore, since the "brake test" is a procedure inherent to safety in operation, it may imply onerous costs of development and certification in accordance with the safety standards in force (EN50126, EN50128, EN50129) as regards the data acquisition and especially transmission system.

In the field of vehicles with rubber wheels, equipment is available for periodically checking a braking system, where the vehicle under test is first positioned on rollers which impart rotation to the wheels and, subsequently, the brakes of the vehicle under test are activated. Finally, the braking torque imparted to the rollers is measured. Based on this measurement, the efficiency of the braking system is evaluated. Obviously, this approach may not be applied in the case of rail vehicles, e.g. a railway vehicle or a railway convoy, at the beginning of each daily mission, due to the complexity of application on each axle of each vehicle making up the convoy and due to the time required to perform it.

Document <CIT> discloses a method of checking the functionality of the brakes of a railway vehicle,.

An object of the present invention is therefore to provide an effective solution which does not involve high costs as regards both the hardware components and the installation and upgrade costs of a possible complete fleet.

A further object is to provide a solution which does not involve expensive development and certification costs in accordance with the safety standards in force at the filing date of the present invention (EN50126, EN50128, EN50129).

The aforesaid and other objects and advantages are achieved, according to an aspect of the invention, by a method for verifying the operation of braking means of at least one vehicle having the features defined in claim <NUM>, by a system for measuring the friction force generated by at least one wheel of at least one vehicle having the features defined in claim <NUM> or <NUM>, and by a system for verifying the operation of braking means of at least one vehicle having the features defined in claim <NUM>. Preferred embodiments of the invention are defined in the dependent claims, the content of which is to be understood as an integral part of the present description.

The functional and structural features of some preferred embodiments of a method for verifying the operation of braking means of at least one vehicle, of a system for measuring the friction force generated by at least one wheel of at least one vehicle and of a system for verifying the operation of braking means of at least one vehicle according to the invention will now be described. Reference is made to the appended drawings, in which:.

Before describing in detail a plurality of embodiments of the invention, it should be clarified that the invention is not limited in its application to the design details and configuration of the components presented in the following description or illustrated in the drawings. The invention is capable of assuming other embodiments and of being implemented or constructed in practice in different ways. It should also be understood that the phraseology and terminology have a descriptive purpose and should not be construed as limiting. The use of "include" and "comprise" and their variations is to be understood as encompassing the elements set out below and their equivalents, as well as additional elements and the equivalents thereof.

Furthermore, throughout the present disclosure and in the claims, the terms and expressions indicating positions and orientations, such as "longitudinal", "transverse", "vertical" or "horizontal", refer to a generic ground <NUM> longitudinal to the travel direction of the one or more vehicles.

As regards the figures, a side view is used and what is shown and described for a wheel supported by a respective rail may be understood as duplicated and applied to a pair of wheels constrained by an axle, and to two rails constituting a track, wherein each rail is associated with each wheel.

Observing for example <FIG>, a braking system of the shoe-on-wheel type is illustrated. A person skilled in the art is able to apply the present invention in a similar way also to a braking system of the pad-on-disc type. With reference to this figure, in the following it is explained by way of example in detail how a friction force generated by a wheel is generated and how it may be calculated.

A wheel <NUM> having angular speed ω(t) rests on a rail <NUM> at the contact point <NUM>. A shoe may exert an equivalent braking force Fa on the wheel <NUM> at a point <NUM>.

At the point of contact <NUM> between the wheel <NUM> and the rail <NUM>, a friction force Fb will consequently be generated.

The equation of equilibrium of the forces acting on the circumference of the wheel <NUM> having a radius r and moment of inertia J, except for rolling frictions not significant for the discussion of the present invention, is reported herein [the wheel <NUM> having angular velocity ω (t)]: <MAT>.

For constant non-zero values of ω(t) we will have: <MAT>.

And therefore, under conditions of constant speed ω(t): <MAT>.

Therefore, being able to measure the friction force Fb in a condition of constant ω(t), the value of the braking force Fa will be obtained directly, irrespective of the physical parameters of the wheel, or of the axle, unless there are forces related to rolling frictions, for example related to bearings, which in any case may be considered negligible for the purpose of the present invention.

In a first aspect, the invention relates to a method for verifying the operation of braking means of at least one vehicle <NUM>, <NUM>,. , <NUM>, in particular at least one railway vehicle.

The at least one vehicle includes at least one axle to which at least one wheel arranged to travel on a rail <NUM>, <NUM>, <NUM> is coupled, and braking means associated with said at least one wheel.

In a first embodiment, the method for verifying the operation of braking means comprises the steps of:.

For example, the friction force Fb may be measured by at least one force sensor means <NUM>, <NUM> or at least one strain gauge sensor means <NUM>.

The order in which steps a) and b) have been previously described is not binding. For example, steps a) and b) may be reversed, as it is sufficient that during the measurement of step c) the following conditions are satisfied, irrespective of the order in which these conditions are obtained:.

In a further embodiment, preferably, the braking means may belong to or be associated with a pneumatic or electro-pneumatic braking system. Therefore, some embodiments applicable for example in the case of pneumatic and/or electro-pneumatic braking systems are reported below.

Preferably, the at least one vehicle may include a brake pipe <NUM> arranged to provide a braking pressure Pf to the braking means associated with said at least one wheel, and the step a) described above may comprise the step of:.

In other words, by directly modifying the value of the braking pressure Pf of the brake pipe, on each wheel to which a braking means is associated, whose braking force generated depends on the braking pressure value Pf provided by the brake pipe, the braking force Fa will be applied.

The pressure in the brake pipe <NUM> may be imposed, for example, by a pressure control means arranged for adjusting the value of the braking pressure Pf.

Preferably, in a further embodiment, the at least one vehicle may include a braking control means associated with said braking means, and said step a) may comprise:
a') by means of said braking control means, actuating said braking means so as to impose the braking force Fa on the at least one wheel <NUM>, <NUM> of said at least one axle of the at least one vehicle <NUM>, <NUM>,.

In this case, preferably, the at least one vehicle may include a main pipe arranged to provide a predetermined braking pressure to the braking means associated with said at least one wheel, and step a') may comprise:.

In other words, for example, the value of the predetermined braking pressure provided by the main pipe may be maintained at a predetermined level, e.g. 8bar - 10bar, but the braking control means will be able to locally adjust the received braking pressure value, so that the actual braking pressure value provided to the braking means is such as to impose the braking force Fa on at least a wheel <NUM>, <NUM> of said at least one axle of the at least one vehicle <NUM>, <NUM>,. In this way, the braking force generated on each wheel may be adjusted independently.

Preferably, the braking means may include, for example, a braking cylinder to which a shoe or a pad is coupled, and may be arranged to act on a wheel or on a disc, respectively. The braking means may further include a "distributor" valve, an auxiliary tank, a pneumatic weighing device <NUM>, a mechanical transmission system <NUM>.

For example, the main pipe and/or the brake pipe may be included in - or associated with - the pneumatic or electro-pneumatic braking system. In the case of a pneumatic or electro-pneumatic braking system, it may be controlled, for example, by a communication bus arranged along the at least one vehicle or along the convoy, in the case of a plurality of vehicles. By means of such bus, for example, it will be possible to provide the various braking controls to the one or more braking control means.

In a further embodiment, preferably, the braking means may belong to or be associated with a pneumatic or electromechanical braking system.

In this case, the at least one vehicle may include an electric line arranged to provide electric energy to the braking means associated with said at least one wheel, and the step a) may comprise the step of:.

Preferably, the braking means may include, for example, an electromechanical assembly to which a shoe or a pad is coupled, and may be arranged to act on a wheel or on a disc, respectively. For example, the electromechanical assembly may comprise an electric motor. The electric motor may, for example, use electric energy to move a mechanical assembly, the movement of which may drive said shoe or pad.

As regards the movement of the at least one vehicle, preferably step b) may comprise:.

The towing action may be carried out, for example, by means of a towing means <NUM>. The towing means may be a locomotive, for example.

Preferably, the at least one vehicle <NUM>, <NUM>,. , <NUM> may include a plurality of axles. Furthermore, at least two wheels may be coupled to each axle. In this case, the previously explained steps c, d), e) may be performed for each wheel of each axle of the at least one vehicle.

Preferably, the vehicles may be at least two <NUM>, <NUM>,. Clearly, each vehicle <NUM>, <NUM>,. , <NUM> may include a plurality of axles and at least two wheels may be coupled to each axle. In this case, the previously explained steps c, d), e) may be performed for each wheel of each axle of each vehicle.

Therefore, summing up for all wheels, it will be possible to:.

For example, the friction forces Fb may be measured by the at least one force sensor means <NUM>, <NUM> or at least one strain gauge sensor means <NUM>.

In a second aspect thereof, the invention relates to a system for measuring the friction force generated by at least one wheel of at least one vehicle, in particular of at least one railway vehicle. Such at least one vehicle comprises at least one axle to which at least one wheel arranged to travel on a rail <NUM>, <NUM>, <NUM> is coupled, braking means associated with said at least one wheel and arranged to produce a braking force Fa on the at least one wheel <NUM>, <NUM>. As may be observed for example in <FIG>, a friction force Fb is exerted by the at least one wheel <NUM>, <NUM>, <NUM>, at a contact point <NUM>, <NUM> between the rail and the at least one wheel, when said braking force Fa is exerted on said at least one wheel. The value of the friction force Fb generated by the at least one wheel is a function of the braking force Fa applied to the at least one wheel.

With reference to <FIG>, in a first embodiment, the system for measuring a friction force <NUM> comprises a movable rail segment <NUM> arranged to allow contact transit of said at least one wheel <NUM> in a measurement step. The contact transit of the at least one wheel <NUM> is arranged to transmit to the movable rail segment <NUM> the friction force Fb which is a function of the braking force Fa. The movable rail segment <NUM> is arranged to slide, according to a transit direction of said at least one wheel <NUM>, due to the friction force Fb generated by said at least one wheel.

The system for measuring a friction force <NUM> comprises at least a first force sensor means <NUM>, for example a force transducer, arranged alongside a first end of the movable rail segment <NUM>. The first force sensor means <NUM> is arranged with respect to the movable rail segment <NUM> so that the movable rail segment <NUM> is arranged to push against the first force sensor means <NUM> when the movable rail segment <NUM> moves in the transit direction, i.e. travel, of the at least one wheel. The first force sensor means <NUM> is arranged to measure the force generated by the sliding of the movable rail segment <NUM> according to the transit direction of the at least one wheel. The force generated by the horizontal sliding of the movable rail segment <NUM> and measured by the first force sensor means <NUM> is substantially correspondent to the friction force Fb generated by the at least one wheel.

Preferably, the system for measuring a friction force <NUM> may further comprise a second force sensor means <NUM>, for example a force transducer, arranged alongside a second end of the movable rail segment <NUM>, opposite to the first end. In this way, the system for measuring the friction force <NUM> may be able to measure the force generated by the sliding of the movable rail segment <NUM> according to both possible transit directions of the at least one wheel.

Preferably, the movable rail segment <NUM> may be arranged to slide on sliding means <NUM> arranged to be placed on a support <NUM>. The support <NUM> may be arranged to be below the movable rail segment <NUM> and constrained to a ground <NUM>.

Preferably, the support <NUM> may be arranged to transmit a vertex force gravitating on it to at least one weight force sensor means <NUM>, for example but not exclusively a force transducer or a load cell.

In an alternative embodiment, the system for measuring a friction force generated by at least one wheel of at least one vehicle, in particular of at least one railway vehicle, comprises at least a first strain gauge sensor means <NUM> arranged to be constrained to one side of the rail <NUM>. The first strain gauge sensor means <NUM> is arranged to be oriented so as to measure said friction force Fb according to a first transit direction of the at least one wheel <NUM> or a second transit direction of the at least one wheel <NUM>, opposite to the first transit direction.

Preferably, the system for measuring a friction force may further comprise a second strain gauge sensor means arranged to be constrained to one side of the rail <NUM>, adjacent to said first strain gauge sensor means <NUM>. The second strain gauge sensor means may therefore be arranged to be oriented so as to measure a weight force acting on the rail.

The first and second strain gauge sensor means may each be a strain gauge sensor or a strain gauge.

In other words, the first and second strain gauge means may functionally replace the first force sensor means and the second force sensor means <NUM>, <NUM> and the at least one weight force sensor means <NUM>, respectively.

Given the low cost of the latter solution, several strain gauge sensor means may be installed along the rail <NUM> along the measurement area in order to be able to perform the measurement simultaneously on several wheels and accelerate the measurement process.

With regard to the systems for measuring the friction force generated by at least one wheel of at least one vehicle described, the at least one vehicle may further include:.

When the vehicle includes the at least one braking control means, the at least one vehicle may include a main pipe arranged to provide a predetermined braking pressure to the braking means associated with said at least one wheel. Wherein, by means of the braking control means, it is possible to adjust the value of the predetermined braking pressure received by said main pipe and to be provided to said braking means, so as to impose the braking force Fa on the at least one wheel <NUM>, <NUM> of said at least one axle of the at least one vehicle <NUM>, <NUM>,.

In another aspect, the invention relates to a system for verifying the operation of braking means for at least one vehicle <NUM>, <NUM>,. , <NUM>, in particular at least one railway vehicle. Again, the at least one vehicle includes at least one axle to which at least one wheel arranged to travel on a rail <NUM>, <NUM>, <NUM> is coupled, and braking means associated with said at least one wheel arranged to produce a braking force Fa on the at least one wheel <NUM>, <NUM>. As already explained above, the friction force Fb is exerted by the at least one wheel <NUM>, <NUM>, <NUM>, at a contact point <NUM>, <NUM> between said rail and said at least one wheel, when said braking force Fa is exerted on said at least one wheel. The value of the friction force Fb generated by the at least one wheel being a function of said braking force Fa applied to the at least one wheel.

In a first embodiment, the system for verifying the operation of braking means includes a system for measuring a friction force according to any one of the embodiments described above.

Furthermore, the system for verifying the operation of braking means includes control means arranged to determine that the braking means associated with the at least one wheel whose measured friction force Fb is lower than a predetermined associated minimum friction force value Fbmin are malfunctioning.

Preferably, the control means may be or may comprise at least one of a microprocessor, a microcontroller, a processor, a controller, a PLC, an FPGA, or the like.

Preferably, the control means may be arranged to identify that the passage of a wheel <NUM>, <NUM>, <NUM> has occurred when they detect a positive peak friction force Fb value.

Preferably, the control means may be arranged to identify that the passage of a wheel <NUM>, <NUM>, <NUM> has occurred when they detect a positive peak weight force value Fp.

Preferably, the control means may be arranged to identify that the passage of a wheel <NUM>, <NUM>, <NUM> has occurred by means of a wheel counting device <NUM> arranged to be installed in proximity to the point of contact between the at least one wheel and the rail wherein the measurement of the friction force Fb takes place. The wheel counting device <NUM> will be able to continuously transmit the information detected by it to the control means by means of a wired or wireless communication means <NUM>.

Preferably, the control means may be arranged to identify that the passage of a wheel <NUM>, <NUM>, <NUM> has occurred by means of a camera <NUM> arranged to be installed in proximity to the contact point between the at least one wheel and the rail where the measurement of the friction force Fb takes place, and at least one image recognition algorithm.

Preferably, the control means may be arranged to assign a unique position identifier along the at least one vehicle to each identified wheel <NUM>, <NUM>, <NUM>.

Preferably, the control means may be arranged to:.

Preferably, the control means may be arranged to compare each friction force Fb measured, associated with each wheel <NUM>, <NUM>, <NUM>, with a respective predetermined minimum friction force value Fbmin associated with each wheel via said unique position identifier along the one or more vehicles.

Preferably, the control means may be arranged to compare each friction force Fb associated to each wheel <NUM>, <NUM>, <NUM> with a predetermined minimum friction force value Fbmin associated to each wheel <NUM>, <NUM>, <NUM>. As may be seen in <FIG>, each minimum friction force value Fbmin associated with each wheel may be arranged to be stored in an array addressed by the unique position identifier along one or more vehicles. The array may be included in a database <NUM> associated with said control means.

Alternatively, or in addition, the control means may be arranged to:.

Each minimum friction force value Fbmin associated with each vehicle <NUM>, <NUM>,. , <NUM> may be arranged to be stored in a first array addressed by the unique position identifier along the one or more vehicles. Again, the array may be arranged to be included in a database <NUM> associated with said control means.

In this case, preferably, the control means may be arranged to:.

Preferably, as may be seen again in <FIG>, the control means may be included in a measurement management system <NUM> comprising a computer system and arranged to receive each value of the friction force Fb measured by the system for measuring a friction force.

With regard to a system for verifying the operation of braking means for at least one vehicle described, the at least one vehicle may further include:.

Hereinafter, to further clarify the operation of the present invention, various implementation examples and examples of use of the present invention will be illustrated.

With reference to <FIG>, a first embodiment of a system for verifying the operation of braking means of at least one vehicle is explained in detail. The wheel <NUM> belongs to a vehicle, in particular a railway vehicle, not shown in the figure, and rests on the movable rail segment <NUM> at the contact point <NUM>. The movable rail segment <NUM> is free to move along the axle X on sliding or rolling means <NUM> resting on a support <NUM>. In the example illustrated, the support <NUM> is considered integral with the mechanical ground reference <NUM>. In the present example, the support <NUM> may also translate vertically along the axis Y and weigh on at least one force sensor <NUM>.

As may be observed in <FIG>, the horizontal movement of the movable rail segment <NUM> is limited in the two directions along the axle X by two rails <NUM>, <NUM> integral with the mechanical ground reference <NUM>.

Two force sensor means, e.g. the first and second force sensor means <NUM>, <NUM>, for example but not exclusively two load cells, measure the force exerted by the movable rail segment <NUM> in its possible horizontal movement along the axle X, respectively on the rail <NUM>, on the left in the figure, and on the rail <NUM>, on the right in the figure.

During the vehicle braking step, braking means including a braking cylinder <NUM> and the shoe <NUM> exerts a braking force Fa on the wheel <NUM> at the equivalent point <NUM>.

Depending on the direction of the wheel <NUM>, in the case of ω(t)=<NUM> one between the first and the second force transducer <NUM>, <NUM>, will measure the friction force FB corresponding to the braking force Fa, i.e. braking exerted by the shoe <NUM> on the wheel <NUM> at the equivalent point <NUM>.

Generally, a braking system for freight transport convoys, according to the prior art, is made by a brake pipe <NUM> whose pressure is controlled by a locomotive towed by one or more vehicles.

The brake pipe <NUM> supplies a device <NUM> known as a "distributor" valve and an auxiliary tank, not shown in the figure. The "distributor" valve <NUM> generates a braking pressure <NUM> as a function of the pressure present in the brake pipe <NUM>, following a transfer function known to those skilled in the art.

A pneumatic weighing device <NUM> receives the braking pressure generated by the "distributor" valve <NUM> and a weight information <NUM>. The weight information <NUM> being for example, but not exclusively, a pressure indicative of the weight of the carriage or vehicle to which the wheel <NUM> belongs. The weight information <NUM> further being, for example but not exclusively, the position of a manually operated indicator which indicates the weight of the carriage or vehicle to which the wheel <NUM> belongs.

A pneumatic weighing device <NUM> generates a weighted braking pressure <NUM> as a function of the braking pressure <NUM> and the weight information <NUM>.

The braking force Fa is a function of the weighted braking pressure <NUM>, the dimensions of the braking cylinder <NUM>, the mechanical transmission system <NUM>, the friction coefficient between the shoe <NUM> and the wheel <NUM>.

Knowing the pressure in the brake pipe <NUM>, the measurement of the friction force Fb by one of the force sensor means <NUM>, <NUM>, is therefore indicative of the state of the braking chain consisting of the "distributor" valve <NUM>, the pneumatic weighing device <NUM>, the mechanical transmission system <NUM>, the shoe <NUM>, the friction coefficient between the shoe <NUM> and the wheel <NUM>.

If the support <NUM> is free to slide vertically along the Cartesian axis Y, and rests on the at least one weight force sensor means <NUM>, for example, but not exclusively load cells, a weight force transducer reads the weight force Fp exerted by the wheel <NUM> on the movable rail segment <NUM>.

Knowing the weight force Fp, it is possible to deduce the weight information <NUM> in input to the pneumatic weighing device <NUM>.

Figure4a illustrates a relationship, known to those skilled in the art, between the braking pressure of the brake pipe Pf and the braking force Fa = friction force Fb, as the weight force increases in the direction of the arrow <NUM>, where Pb=5bar nominal and Pr=<NUM>. 5bar nominal, where the tare braking force value Fa(T) and the full load braking force Fa(FL) are specific values for a specific vehicle model.

Figure 4b illustrates a possible relationship, known to those skilled in the art, as the weight force varies between the tare value Fp(T) and the full load value Fp(FL) and the braking force Fa = friction force Fb for a constant value of braking pressure of the brake pipe , for example Pf = <NUM> bar, for a specific vehicle model.

The parameters Fa(T), Fa(FL), Fp(T), Fp(FL) will be defined below as "vehicle weighing braking parameters".

Knowing the braking pressure Pf in the brake pipe <NUM>, the weight force Fp, the measure of the friction force Fb = braking force Fa, it is therefore possible to have a better accuracy in evaluating the state of the braking means (also said braking chain) comprising the "distributor" valve <NUM>, the pneumatic weighing device <NUM>, a mechanical transmission system <NUM>, the shoe <NUM>, the friction coefficient between the shoe <NUM> and the wheel <NUM>.

A first implementation example of a method for verifying the operation of braking means for at least one vehicle is also described below.

Referring to <FIG>, a locomotive <NUM> may tow a convoy, in particular a railway convoy, made by at least one vehicle <NUM>, <NUM>,. , <NUM>, at a constant speed in order to keep the angular acceleration of each wheel of the train at zero, or <MAT>, transiting on a system for measuring a friction force. In the present example, in addition to the locomotive, three other vehicles <NUM>, <NUM>, <NUM> are illustrated, each having four axles, for a total of <NUM> wheels per vehicle.

Furthermore, the locomotive <NUM> may control a known constant pressure Pf, such as to urge the braking means of the at least one vehicle <NUM>, <NUM>,. , <NUM> to apply a braking force Fa, and at the same time such as to allow said locomotive <NUM> to continue towing the convoy at constant speed.

Otherwise, the locomotive <NUM> may control a constant braking pressure Pf such as to guarantee the measurement conditions described in the previous paragraph, the value of which depends further on local instantaneous operating conditions, and transmits said pressure value Pf via a wireless channel to a measurement management system <NUM>, the function of which will be detailed later.

A system for measuring a friction force <NUM> will be able to measure the friction force Fb exerted by each wheel on the movable rail segment <NUM> forming part of the system for measuring a friction force <NUM>.

The system for measuring a friction force <NUM> will be able to continuously transmit the measured friction value Fb of each wheel of the at least one vehicle <NUM>, <NUM>,. , <NUM> to a measurement management system <NUM> via a wired or wireless communication means <NUM>.

If the support <NUM> is free to slide vertically along the Cartesian axis Y, the at least one weight force sensor means <NUM> reads the weight force Fp exerted by the wheel <NUM> on the movable rail segment <NUM> and continuously transmits the weight force value Fp measured, corresponding to each wheel of the at least one vehicle <NUM>, <NUM>,. , <NUM>, to the computer measurement management system <NUM> by means of the wired or wireless communication means <NUM>.

Such measurement management system <NUM> will be able to identify the passage of a wheel according to at least one of the following methods:.

As each wheel passes, the measurement management system <NUM> may associate a unique identifier consisting of an incremental numerical value to each wheel and saves it in a database <NUM>, e.g. database, together with the corresponding measured friction force value Fb and possibly with the corresponding measured weight force value Fp.

The database <NUM> may contain the configuration of the convoy, that is the position of each vehicle inside the convoy and the number of axles of each vehicle. In this way, the centralized measurement management system <NUM> will be able to associate each braking force measurement Fb to each wheel of each vehicle <NUM>, <NUM>,.

During a first example of a brake test of a convoy, in particular a railway convoy, comprising at least one vehicle <NUM>, <NUM>. <NUM>, towed by a locomotive <NUM> at constant speed, when said locomotive <NUM> applies a braking pressure Pf in the brake pipe <NUM>, the following steps may be carried out:.

Otherwise, during a second example of a brake test of a convoy, in particular a railway convoy, comprising at least one vehicle <NUM>, <NUM>. <NUM>, towed by the locomotive <NUM> at constant speed, when said locomotive <NUM> applies a braking pressure Pf in the brake pipe <NUM>, the following steps may be carried out:.

Still otherwise, during a third example of a brake test of a convoy, in particular a railway convoy, comprising at least one vehicle <NUM>, <NUM>. <NUM>, towed by a locomotive <NUM> at constant speed, when said locomotive <NUM> applies a predetermined braking pressure Pf in the brake pipe <NUM>, the following steps may be carried out:.

A further implementation example of a method for verifying the operation of braking means of at least one vehicle, in particular at least one railway vehicle, is described below:.

Method for verifying the operation of braking means of at least one railway vehicle <NUM>, <NUM>,. , <NUM>, wherein said at least one railway vehicle includes:.

said method for verifying the operation of braking means comprising the steps of:.

The advantage achieved is therefore that of having provided an effective solution but without implying high costs both as regards the hardware components and as regards the installation and upgrade costs of the complete fleet.

The at least one vehicle to which the present invention is applicable, in addition to the railway field, may be applied analogously to any vehicle traveling on rails.

A further advantage achieved is that of having provided a solution which does not involve expensive development and certification costs in accordance with the safety standards in force (EN50126, EN50128, EN50129).

Claim 1:
Method for verifying the operation of braking means of at least one vehicle (<NUM>, <NUM>, ..., <NUM>), in particular at least one railway vehicle, wherein said at least one vehicle includes:
- at least one axle to which at least one wheel arranged to travel on a rail (<NUM>, <NUM>, <NUM>) is coupled;
- braking means associated with said at least one wheel;
said method for verifying the operation of braking means comprising the steps of:
a) imposing, by means of said braking means, a braking force (Fa) on the at least one wheel (<NUM>, <NUM>) of said at least one axle of the at least one vehicle (<NUM>, <NUM>, ..., <NUM>);
b) moving said at least one vehicle (<NUM>, <NUM>, ..., <NUM>), so that said at least one vehicle moves at a non-zero and constant forward speed;
c) measuring on the rail (<NUM>, <NUM>, <NUM>) at least one friction force (Fb) which is a function of said braking force (Fa), the at least one friction force (Fb) being exerted by said at least one wheel (<NUM>, <NUM>, <NUM>) at a contact point (<NUM>, <NUM>) between said rail and said at least one wheel;
d) comparing the at least one measured friction force (Fb) with a predetermined minimum friction force value (Fbmin);
e) determining that the braking means associated with the at least one wheel whose measured friction force (Fb) is lower than said predetermined minimum friction force value (Fbmin) are malfunctioning.