Reivindicaciones
1. An installation for the automatic evaluation of the condition of the rolling band on wheels of moving trains, especially for the detection of cracks in said rolling band, characterized in that it comprises a support structure made of steel, consisting of a rail beam (1) for each railway line (8), replacing a section of the latter and over which the flange of the train wheels (9) is made to run, assuring the continuity between the rail beam and the railway line by means of a bolted joint (3); a guard-rail (2) attached to each rail beam to ensure the guidance of the wheels while they move leaning with their flange over the rail beam; feelers (P) destined to come into contact with the wheels passing over them; feeler holders (4) installed on the rail beam and each one of them provided with two guides (5) and a swinging spring (6), such that the passage of the wheels over the feelers forces and assures the wheel-feeler contact; an ultrasonics equipment (12) to transmit towards the passing wheels ultrasonic pulses with programmable frequency and duration and to generate and acquire the ultrasonic plots corresponding to the wheels; a local processor (13) to control the ulstrasonics equipment and receive from it, digitally, the signals from the ultrasonics plots generated; a computer (14) connected to the local processor and responsible for transmitting the activation orders of the ultrasonic equipment, collecting, organizing and storing the measurement results and generating the pertinent reports; and an antenna (15) connected to the computer and destined to identify the measured train compositions. 2. An installation according to claim 1, characterized in that the feeler holders (4) may be activated and deactivated to move vertically by means of two guides (7) provided for them. 3. An installation according to claims 1 and 2, characterized in that it includes at least two feelers (P1, P2; P3, P4) for each railway line (8). 4. An installation according to claim 3, characterized in that it includes four of said feelers for each rail. 5. An installation according to the preceding claims, characterized in that each one of the feelers (P) consists of a piezoelectric transducer to generate and receive ultrasonic surface waves, using a dry coupling means and incorporating two inductive proximity detectors (11) to indicate the presence of a wheel (9) over the transducer. 6. An installation according to claim 5, characterized in that the surface waves generated and received by each transducer are of 1 MHz and the dry coupling means used in each transducer is a crude rubber film. 7. An installation according to the preceding claims, characterized in that the ultrasonics equipment (12) is designed for the generation, acquisition and processing in real time of ultrasonic signals for the execution of nondestructive testing of materials and consists of an analogical part (16) and a digital part (17), where said analogical part comprises analogical treatment modules (18) for treating the ultrasonic signals to be acquired, including programmable gain amplifiers and prefiltering, detection, logarithmic amplification and channel multiplexing stages, and said digital part includes a bus (21) with segmented architecture and a set of dedicated processor modules (MP0, MP1, MP2, ...) with high effectiveness, said bus consisting of segments separated by boardbases over which the processor modules are housed. 8. An installation according to claim 7, characterized in that said programmable gain is 80 dB at 20 MHz and said logarithmic amplification is 100 dB. 9. An installation according to claims 7 and 8, characterized in that the analogical part (16) of the ultrasonics equipment (12) is housed on an analogical base card (BANG) serving as a support for the analogical amplification-filtering modules through a series of slots (SLO, SL1, SL2, SL3, ...) with analogical channels (CN0-1, CN2-3, CN4-5, CN6-7, ...) in each one of them, and moreover containing a stabilized voltage generation system for the supply of the analogical modules, the input channel selection circuitry (27) and an analogical module (28) for envelope detection, these modules being governed through the control bus (29) of the analogical base card. 10. An installation according to claim 9, characterized in that said analogical part includes an additional slot (DIG) joined directly to the control bus (29) and suitable to add a digital input-output card for the detection of presence of wheels (9). 11. An installation according to claims 7 to 10, characterized in that the digital part (17) of the ultrasonics equipment (12) is housed on a remote digital base card (BDR), which serves as a support for the digital and hybrid architecture processing modules, which are inserted on baseboards (ZO, Z1, Z2, Z3, ...) joined to the control bus (32) of the digital base card, each baseboard being joined to the following baseboard by means of the segmented signal bus (21) through which it receives the data processed by the previous module and delivers its results to the following module, and the output of each module being joined to a results memory (24), said digital base card further containing a communications subsystem (25) for the reception of orders and transmission of results, as well as a local processor (13) governing the entire digital base card and entrusted with programming the modules, attending the communications and triggering the acquisition and processing of signals. 12. An installation according to claims 7 to 11, characterized in that both the analogical base card (BANG) and the remote digital base card (BDR) are connected to a power supply (33). 13. An installation according to claims 7 to 12, characterized in that the analogical base card (BANG) incorporates four slots (SL0, SL1, SL2, SL3) with two analogical channels (CN0-1, CN2-3, CN4-5, CN6-7) each one and the remote digital base card (BDR) incorporates four baseboards (Z0, Z1, Z2, Z3). 14. An installation according to the preceding claims, characterized in that the ultrasonics equipment (12) includes a series of programmable pulse generators (PS1, PS2, PS3, PS4, ...) connected to the feelers (P1, P2; P3, P4, ...) and to the amplification modules, a proximity sensor control module (32) being installed in the digital input/output slot (DIG) of the analogical base card (BANG) and a gain control module (CAT), an analogical/digital conversion module (A/D) and a data reduction module (REDUC) being installed on the remote digital base card (BDR). 15. An installation according to claim 14, characterized in that four programmable pulse generators (PS1, PS2, PS3, PS4) are provided and two amplification modules, installed on the analogical base card (BANG), each one of which incorporate two linear amplifiers (AMP1, AMP2, AMP3, AMP4) with variable gain.
