Method for monitoring the proper working of a sanding system of a rail vehicle

Abstract

The invention relates to a method and an assembly for monitoring the proper working of a sanding system of a rail vehicle (SFZ). The sanding system comprises a sand container (SB1), a sand-conveying system (SFS1) and a pipe (RL), wherein the sand container (SB1) is connected to the pipe (RL) via the sand-conveying system (SFS1). The sand-conveying system (SFS1) is used for the compressed-air-assisted conveying of sand out of the sand container (SB1). A sand-and-compressed-air mixture (SA) is dispensed into the pipe (RL) by means of the sand-conveying system (SFS1). The sand-and-compressed-air mixture (SA) is passed on through the pipe (RL). A sensor (AS, OS, KS) is used for monitoring the sand-and-compressed-air mixture (SA) passed on through the pipe. Sensor signals assigned to the sensor are transmitted to a sanding-monitoring system (SWG) for evaluation, wherein the sanding-monitoring system (SWG) detects problems in the sand-and-compressed-air mixture (SA) on the basis of the sensor signals.

Description

Method for monitoring the proper working of a sanding system of a rail vehicle The invention relates to a method and an arrangement for monitoring the proper working of a sanding system of a rail vehicle. Using a sanding system in a rail vehicle to improve a wheel-rail traction is known. Using this system, small amounts of sand are introduced in front of a wheel of the rail vehicle into a wheelrail gap as needed, for example when braking or when driving off the rail vehicle. A wheel-rail coefficient of friction is thus increased, so that the rail vehicle can transmit a higher drive force or braking force to the rail. The sanding system is an operationally important device. If it is disturbed or nonfunctioning, in certain situations, for example in the case of icy rails or during a hill start, a travel interruption of the rail vehicle can be the result. The sanding system is also a safety-relevant device, since it significantly reduces a required braking distance in emergency situations, for example in the event of strong braking actions. The sanding system therefore has to have a high level of availability and a high functional reliability, which is ensured by regularly occurring maintenance and checking of the sanding system on the rail vehicle. During the maintenance, the sanding system is filled with sand and subjected to a test for proper working before beginning a journey. Figure 2 shows a known sanding system with associated components for a rail vehicle SFZ. For a first travel direction FR1 of the rail vehicle SFZ, sand SA is conveyed out of a first sand container SB1 by means of compressed air via a first sand conveyor system SFS1 and introduced via a pipeline in front of a wheel of a driven first axle A1 in a wheel-rail gap RSSP. Accordingly, for a second travel direction FR2 of the rail vehicle SFZ, sand SA is conveyed from a second sand container SB2 by means of compressed air via a second sand conveyor system SFS2 and introduced via a pipeline in front of wheels of a driven second axle A2 into the wheel-rail gap RSSP there. The compressed air acts, for example, directly on an outlet area of the sand container SB1, SB2 or acts on a sand conveyor system SFS1, SFS2, which is connected to the respective outlet area of the sand container SB1, SB2. The compressed air is mixed with a defined amount of sand and is guided as a sand-compressed air mixture SA via a pipeline into the wheel-rail gap RSSP. The compressed air required to convey and discharge the sand is provided by a compressed air supply DVS. The compressed air supply DVS is connected via a shut-off valve AB1 and via respective compressed air lines to both sand containers SB1, SB2. It is ensured by the shut-off valve AB1 that in the event of leaks or disturbances, the sanding system is manually disconnectable from the compressed air system. A selection of the sanding via the first sand container SB1 or via the second sand container SB2 takes place with the aid of electro-pneumatic valves EP1, EP2, which ensure the compressed air supply of one of the two sand containers SB1, SB2 in terms of a selection circuit. For this purpose, a first valve EP1 is connected between the compressed air supply DVS and the first sand conveyor system SFS1, while a second valve EP2 is connected between the compressed air supply DVS and the second sand conveyor system SFS2. If the sanding is to take place via the first sand container SB1 for the first travel direction FR1, the first valve EP1 is opened and the second valve EP2 is closed. Compressed air thus passes from the compressed air supply DVS to the first sand conveyor system SFS1. If the sanding is to take place via the second sand container SB2 for the second travel direction FR2, the second valve EP2 is opened and the first valve EP1 is closed. Compressed air thus passes from the compressed air supply DVS to the second sand conveyor system SFS2. The two valves EP1, EP2 are actuated via respective signals, identified here as the signal STSIG, of a controller ST. The controller influences the sand delivery amount via pulses and controls the sanding of the first drive axle A1 or the second drive axle A2. In a specific situation (snow, ice, braking, hill start, etc.), the delivery of the amount of sand is triggered via a sanding request ANF, which acts on the controller ST. The sanding request ANF is typically triggered by an operating action of the vehicle driver or via an automatic request by the drive system or braking system of the rail vehicle. Vehicle parameters FPAR, for example a vehicle speed and the currently selected travel direction FR1, FR2, are also supplied to the controller ST for delivering the amount of sand. On the basis of the request ANF and the vehicle speed as well as the travel direction, the controller ST generates the control commands for the pneumatic valves EP1, EP2. The controller ST is entirely or partially integrated into a control technology unit LT of the rail vehicle. If such a sanding system fails during the operative control of the rail vehicle, this failure is recognized either too late or not at all by the vehicle driver. Disturbances during the journey are at most noticed by the vehicle driver in that an actuation of the sanding system has no or only a minor effect. A device for monitoring the flow of scattered material in vehicles according to the preamble of the following patent claims is known from document EP 1713647 B1. A device for flow rate monitoring of a sand scattering device for vehicles is known from document DE 102014112742 A1. A sound sensor arranged on a channel and an evaluation unit coupled with the sound sensor are used for the monitoring. A method for adjusting a sand conveyor system of a locomotive is known from document CN 115649205. A diagnostic device for a sand metering unit for a sanding system of a rail vehicle is known from document DE 102020104216 A1. 2024230211   31 Aug 2026 It is an object of the present invention to substantially overcome or at least ameliorate one or more of the deficiencies of the prior art and / or to provide a useful alternative. The invention relates to a method and an arrangement for monitoring the proper working of a sanding system of a rail vehicle. With the above in mind, one aspect of this disclosure provides an arrangement for monitoring a sanding system of a rail vehicle, - having a sanding system of a rail vehicle, which comprises a sand container, a sand conveyor system , and a pipeline, - in which the sand container is connected via the sand conveyor system to the pipeline, - in which the sand conveyor system is designed for the compressed air-assisted conveyance of sand from the sand container, - in which the sand conveyor system is designed to deliver a sand-compressed air mixture into the pipeline, - in which the pipeline is designed to pass on and deliver the sand-compressed air mixture, - having a sensor, which is arranged to monitor the sand-compressed air mixture that is conducted through the pipeline, - having a sanding monitoring unit, which is connected to the sensor, in order to evaluate its sensor signals, - in which the sanding monitoring unit is designed to recognize a disturbance in the sand-compressed air mixture on the basis of the sensor signals, wherein - the sensor is an optical sensor, which is positioned in the area of a wheel-rail gap of the rail vehicle, - the sensor is designed to recognize a sand amount which is introduced via the pipeline into the wheel-rail gap, and - wherein the sand amount is part of the sensor signal. 2024230211   31 Aug 2026 Another aspect of this disclosure provides a method for monitoring a sanding system of a rail vehicle, - wherein a sanding system of the rail vehicle comprises a sand container, a sand conveyor system, and a pipeline, and wherein the sand container is connected via the sand conveyor system to the pipeline, - in which a compressed air-assisted conveyance of sand from the sand container takes place through the sand conveyor system, - in which a sand-compressed air mixture is delivered into the pipeline through the sand conveyor system, -  in which the sand-compressed air mixture is passed on through the pipeline, -  in which a sensor is used to monitor the sand-compressed air mixture, which is conducted through the pipeline, -  in which the sensor transmits assigned sensor signals to a sanding monitoring unit for evaluation, -  in which the sanding monitoring unit recognizes a disturbance in the sand-compressed air mixture on the basis of the sensor signals, wherein -  an optical sensor is used as the sensor, which is positioned in the area of a wheel-rail gap of the rail vehicle, -  the sensor recognizes a sand amount which is introduced via the pipeline into the wheel-rail gap, and -  the sand amount forms a part of the sensor signal. The sanding system comprises a sand container, a sand conveyor system, and a pipeline, wherein the sand container is connected via the sand conveyor system to the pipeline. The sand conveyor system is designed for the compressed air-assisted conveyance of sand from the sand container. The sand conveyor system is designed to deliver a sand-compressed air mixture into the pipeline. The pipeline is designed to pass on and deliver the sand-compressed air mixture, preferably into a wheel-rail gap of the rail vehicle. 2024230211   31 Aug 2026 According to the invention, a sensor for monitoring the sand-compressed air mixture which is conducted through the pipeline is provided or arranged. A sanding monitoring unit is connected to the sensor in order to evaluate its sensor signals. The sanding monitoring unit is designed to recognize a disturbance in the sand-compressed air mixture on the basis of the sensor signals. In one advantageous refinement, the sensor is an acoustic sensor and is designed to record a through-flow noise as a sensor signal. The through-flow noise is formed by the sand-compressed air mixture in the pipeline. In one advantageous refinement, the sanding monitoring unit is designed to distinguish the following sound forms based on the sensor signal of the acoustic sensor, namely: - when sand is not conducted or is conducted without compressed air participation via the pipeline, - when compressed air is conducted without sand participation via the pipeline, or - when sand mixed with compressed air is conducted via the pipeline. In one advantageous refinement, the sensor is an optical sensor which is positioned in the pipeline or close to an outlet opening of the pipeline. The sensor is designed to recognize a sand proportion in the sand-compressed air mixture, wherein the sand proportion is part of the sensor signal or the sensor signal reflects the sand proportion. In one advantageous refinement, the sanding monitoring unit is designed to recognize the following states based on the sensor signal of the optical sensor, namely: - when no sand is conducted via the pipeline, - when too much or too little sand is conducted via the pipeline, or - when sand with a correct proportion in the sand-compressed air mixture is conducted via the pipeline (RL). According to the invention, the sensor is an optical sensor which is positioned in the area of a wheel-rail gap of a rail vehicle. The sensor is designed to recognize a sand amount which is introduced via the pipeline into the wheel-rail gap. The sand amount is part of the sensor signal or the sensor signal reflects the sand amount. In one advantageous refinement, the sanding monitoring unit is designed to recognize the following states based on the sensor signal of the optical sensor, namely: - when no sand enters the wheel-rail gap, - when too much or too little sand enters the wheel-rail gap, or - when the sand amount enters the wheel-rail gap next to the rail. In one advantageous refinement, in a rail vehicle, each pipeline provided for sanding is monitored by a sensor. In one advantageous refinement, the sanding monitoring unit is connected to a control technology unit of a rail vehicle and / or to a fixed supervision office, in order to initiate suitable measures if a disturbance is detected. Automatic and autonomous monitoring of the sanding system of a rail vehicle for disturbances is implemented by the present invention. The present invention can also be applied or carried out in a rail vehicle without vehicle driver. The present invention can be retrofitted in existing vehicles with little effort and with low costs. Maintenance costs are reduced and previously required complex tests and checks on the rail vehicle are reduced or avoided by the present invention. An upgrade time of the rail vehicle is reduced by the present invention. The present invention enables a documentation of recognized disturbances, which is preferably performed with the aid of a data transmission from the rail vehicle to a fixed supervision office, which is referred to as the land side. Informing maintenance depots about the status of a sanding system of an assigned rail vehicle from running operation is thus made possible. Maintenance activities can thus be planned better and more effectively. The present invention enables an empty status of a sand container to be predicted and indicated in a timely manner. Costs in operation and maintenance of the rail vehicle are thus reduced. The invention is explained in more detail hereinafter with the aid of a drawing. In the figures: Figure 1 shows an exemplary embodiment of the invention, and Figure 2 shows the known sanding system of a rail vehicle described in the introduction. Figure 1 shows an exemplary embodiment of monitoring according to the invention of a sanding system of a rail vehicle. For a first travel direction FR1 of the rail vehicle SFZ, sand SA is conveyed out of a first sand container SB1 by means of compressed air via a first sand conveyor system SFS1 and reaches a wheel-rail gap RSSP in front of wheels of a driven first axle A1 as a sand-compressed air mixture SA via a pipeline RL. For a second travel direction FR2 of the rail vehicle SFZ, sand SA is conveyed out of a second sand container SB2 by means of compressed air via a second sand conveyor system SFS2 and reaches a wheel-rail gap RSSP in front of wheels of a driven second axle A2 as a sand-compressed air mixture SA via a pipeline RL. The compressed air is blown, for example, into an outlet area of the sand container SB1, SB2 or into the respective sand conveyor system SFS1, SFS2 and mixed there with a defined amount of sand. The compressed air required to convey the sand SA and to discharge the sand into the wheel-rail gap RSSP is provided with the aid of a compressed air supply DVS. The compressed air supply DVS is connected via a shut-off valve AB1 and via respective compressed air lines to both sand containers SB1, SB2. It is ensured by the shut-off valve AB1 that the sanding system is manually disconnectable from the compressed air system in the event of leaks or disturbances. A selection of the sanding via the first sand container SB1 or via the second sand container SB2 takes place with the aid of electro-pneumatic valves EP1, EP2, which ensure selective compressed air supply of one of the two sand containers SB1, SB2 or of one of the two sand conveyor systems SFS1, SFS2. For this purpose, a first valve EP1 is connected between the compressed air supply DVS and the first sand conveyor system SFS1, while a second valve EP2 is connected between the compressed air supply DVS and the second sand conveyor system SFS2. If the sanding is to take place via the first sand container SB1 for the first travel direction FR1, the first valve EP1 is opened and the second valve EP2 is closed. Compressed air thus reaches the first sand conveyor system SFS1 from the compressed air supply DVS. If the sanding is to take place via the second sand container SB2 for the second travel direction FR2, the second valve EP2 is opened and the first valve EP1 is closed. Compressed air thus reaches the second sand conveyor system SFS2 from the compressed air supply DVS. The two valves EP1, EP2 are actuated via signals, which are shown here as the signal STSIG, of a controller ST as a function of the travel direction FR1, FR2. The sand delivery takes place with the aid of pulses in the signals STSIG, which are generated via the controller ST. Vehicle parameters FPAR, for example a vehicle speed, as well as the desired travel direction FR1, FR2, are supplied to the controller ST to control the sand delivery amount. The controller ST generates the signals STSIG used for the control based thereon. The controller ST is entirely or partially integrated into a control technology unit LT of the rail vehicle SFZ. A sand delivery triggered by the controller ST is initiated by a sanding request ANF, which acts on the controller ST. The sanding request ANF is triggered manually by a vehicle driver or is triggered automatically by a drive / braking system of the rail vehicle. The sanding request ANF also acts on a sanding monitoring unit SWG, which is designed to recognize a disturbance of the sanding system or the sanding. If no disturbance exists, this is signaled by the sanding monitoring unit SWG to the controller ST, so that the sanding is performed thereby. However, if a disturbance exists, this is signaled by the sanding monitoring unit SWG to a control technology unit LT of the rail vehicle, which makes suitable decisions or reactions to minimize the effect of the disturbance. Alternatively or additionally thereto, the presence of the disturbance is reported with the aid of a remote data transfer from the rail vehicle to a fixed supervision office LS referred to as the land side. The supervision office LS monitors the rail vehicle status and makes suitable decisions or reactions to minimize the effect of the disturbance. For example, - the vehicle driver of the rail vehicle is informed, and / or - an accelerated maintenance of the rail vehicle is initiated, and / or - a modified sanding plan is created for the rail vehicle -for example, the pulses required for sanding are changed over time - by the control technology unit LT and / or by the supervision office LS. To be able to monitor the function of the sanding or to be able to recognize a disturbance of the sanding, the sanding monitoring unit SWG is coupled with a suitable sensor. Assigned sensor information is collected by the sanding monitoring unit SWG and transmitted thereby to the control technology unit LT, and input and processed therein. It is thus possible to continuously monitor the function of the sanding and its components and to recognize errors or disturbances in operation immediately. Three different embodiments are described hereinafter, which are usable individually or combined with one another for monitoring. In a first embodiment, the pipeline RL is monitored with the aid of an acoustic sensor AS. A through-flow noise, which is formed by the sand-compressed air mixture SA, is recorded with the aid of the sensor in the pipeline RL. Three different sound forms are distinguishable with the aid of the acoustic sensor AS: - No compressed air is present, so that the sand SA is discharged without compressed air participation. A disturbance in the compressed air supply DVS or in the associated compressed air-conducting components AB1, EP1, EP2 can be concluded therefrom. Leaks and / or clogs in these components are therefore detectable. - Only compressed air without sand SA is discharged. A disturbance in the sand containers or in the sandconducting components can be concluded therefrom. Disturbances in the sand containers SB1, SB2 (clogging of the sand container outlet, deficiency of sand, clumps in the sand) and clogs in the sand pipeline system (RL) are therefore detectable. - Sand mixed with compressed air is discharged. Depending on the through-flow noise, an error-free status or a discharge of an excessively small sand amount or a discharge of an excessively large sand amount is then detectable. Assigned sensor signals SAK of the acoustic sensor AS reach the sanding monitoring unit SWG for collection and evaluation via an acoustic monitoring unit AUEW. The acoustic monitoring unit AUEW generates information based on the sensor signals SAK, as to whether or not sand is guided through the monitored pipeline RL at the observed time, which is determined by the sanding request ANF. It provides this information to the sanding monitoring unit SWG. In a second embodiment, the pipeline is monitored with the aid of an optical sensor OS, wherein the optical sensor OS is preferably positioned in the pipeline RL or at its outlet opening. The sand or the sand proportion in the sand-compressed air mixture is recognized by the optical sensor OS. Assigned sensor signals SOD of the optical sensor OS reach the sanding monitoring unit SWG for collection and evaluation via an optical monitoring unit OUEW. The optical monitoring unit OUEW generates information based on the sensor signals SOD as to whether or not sand is guided through the monitored pipeline RL at the observed time, which is determined by the sanding request ANF. It provides this information to the sanding monitoring unit SWG. In a third embodiment, the wheel-rail gap RSSP or the rail surface there is monitored with the aid of an optical sensor KS. The optical sensor KS is accordingly positioned close to the wheel-rail gap RSSP or close to the rail surface there. The discharged sand or the discharged sand amount is recognized by the optical sensor KS. In addition, it is additionally recognized with the aid of the optical sensor KS whether the sand is possibly discharged incorrectly next to the rail. Assigned sensor signals SOG of the optical sensor KS reach the sanding monitoring unit SWG for collection and evaluation via an optical monitoring unit SUEW. The optical monitoring unit SUEW generates information based on the sensor signals SOG as to whether or not sand is discharged at the observed time, which is determined by the sanding request ANF. It provides this information to the sanding monitoring unit SWG. The monitoring units AUEW, OUEW, and SUEW thus continuously form information as to whether sand is correctly discharged through the pipeline RL or whether the sand correctly reaches the rail in front of the wheel viewed in the travel direction. They provide this information to the monitoring unit SWG, which continuously compares the information with the sanding request ANF. The sanding monitoring unit SWG continuously generates therefrom the information as to whether the sanding system works correctly. It recognizes - whether sand is discharged per wheel if the sanding request ANF is present in valid form, or - whether no sand is incorrectly discharged per wheel if the sanding request ANF is present in valid form, or - whether sand is incorrectly discharged per wheel although the sanding request ANF is not present. Preferably, the sanding request ANF is formed for each wheel axle A1, A2 or for each individual wheel of the wheel axles A1, A2. Preferably, each pipeline RL is individually monitored for each wheel or wheel axle. This enables disturbances and malfunctions in parts of the sanding system to be recognized. Additionally thereto, a respective fill level of the sand container SB1, SB2 is continuously monitored with the aid of a sensor. If a calculated remaining sand amount in the container SB1, SB2 falls below a predetermined value, associated information is transmitted via the control technology unit LT to the vehicle driver or to the supervision office LS. A maintenance of the rail vehicle is therefore implemented in a timely manner to refill the required sand.

Claims

1. An arrangement for monitoring a sanding system of a rail vehicle,- having a sanding system of a rail vehicle, which comprisesa sand container, a sand conveyor system , and a pipeline,- in which the sand container is connected via the sand conveyor system to the pipeline,- in which the sand conveyor system is designed for the compressed air-assisted conveyance of sand from the sand container,- in which the sand conveyor system is designed to deliver asand-compressed air mixture into the pipeline,- in which the pipeline is designed to pass on and deliverthe sand-compressed air mixture,- having a sensor, which is arranged to monitor the sand-compressed air mixture that is conducted through the pipeline,- having a sanding monitoring unit, which is connected to the sensor, in order to evaluate its sensor signals,- in which the sanding monitoring unit is designed to recognize a disturbance in the sand-compressed air mixture on the basis of the sensor signals, wherein- the sensor is an optical sensor, which is positioned in thearea of a wheel-rail gap of the rail vehicle,- the sensor is designed to recognize a sand amount which isintroduced via the pipeline into the wheel-rail gap, and- wherein the sand amount is part of the sensor signal.

2. The arrangement as claimed in claim 1, wherein- the pipeline is monitored by an acoustic sensor,- the acoustic sensor is designed to record a through-flow noise as a sensor signal, and2024230211   31 Aug 2026- in which the through-flow noise is formed by the sand-compressed air mixture in the pipeline.

3. The arrangement as claimed in claim 2, wherein, based on thesensor signal of the acoustic sensor, the sanding monitoring unit is designed to distinguish the following sound forms,namely:- when sand is conducted without compressed air participation via the pipeline,- when compressed air is conducted without sand participation via the pipeline, or- when sand mixed with compressed air is conducted via the pipeline.

4. The arrangement as claimed in claim 1, wherein - the pipeline is monitored by an optical sensor, - the optical sensor is positioned in the pipeline or close to an outlet opening of the pipeline, and- the optical sensor is designed to recognize a sand proportion in the sand-compressed air mixture, wherein thesand proportion is part of the sensor signal.

5. The arrangement as claimed in claim 4, wherein, based on thesensor signal of the optical sensor, the sanding monitoring unit is designed to recognize the following states, namely: - when no sand is conducted via the pipeline, - when too much or too little sand is conducted via the pipeline, or- when sand with a correct proportion in the sand-compressed air mixture is conducted via the pipeline.

6. The arrangement as claimed in claim 1, wherein, based on thesensor signal of the optical sensor, the sanding monitoring unit is designed to recognize the following states, namely: - when no sand enters the wheel-rail gap,2024230211   31 Aug 2026- when too much or too little sand enters the wheel-rail gap,or- when the sand amount enters the wheel-rail gap next to therail.

7. The arrangement as claimed in any one of the preceding claims, wherein, in the rail vehicle, each pipeline provided for sanding is monitored by a sensor.

8. The arrangement as claimed in any one of the preceding claims, wherein the sanding monitoring unit is connected to a control technology unit of the rail vehicle and / or to a fixed supervision office, in order to initiate measures in the event of a detected disturbance.

9. A method for monitoring a sanding system of a rail vehicle,- wherein a sanding system of the rail vehicle comprises asand container, a sand conveyor system, and a pipeline, and wherein the sand container is connected via the sand conveyor system to the pipeline,- in which a compressed air-assisted conveyance of sand from the sand container takes place through the sand conveyorsystem,- in which a sand-compressed air mixture is delivered intothe pipeline through the sand conveyor system,- in which the sand-compressed air mixture is passed on through the pipeline,- in which a sensor is used to monitor the sand-compressedair mixture, which is conducted through the pipeline,- in which the sensor transmits assigned sensor signals to asanding monitoring unit for evaluation,- in which the sanding monitoring unit recognizes a disturbance in the sand-compressed air mixture on the basis of the sensor signals,wherein2024230211   31 Aug 2026- an optical sensor is used as the sensor, which is positionedin the area of a wheel-rail gap of the rail vehicle,- the sensor recognizes a sand amount which is introduced viathe pipeline into the wheel-rail gap, and- the sand amount forms a part of the sensor signal.

10. The method as claimed in claim 9, wherein an acoustic sensor, which records a through-flow noise as a sensor signal, is used to monitor the pipeline, wherein the through-flow noise is formed by the sand-compressed air mixture in the pipeline.

11. The method as claimed in claim 10, wherein based on the sensor signal of the acoustic sensor, the sanding monitoring unit distinguishes the following sound forms, namely: - when sand is not conducted or is conducted without compressed air participation via the pipeline,- when compressed air is conducted without sand participation via the pipeline, or- when sand mixed with compressed air is conducted via the pipeline.

12. The method as claimed in claim 9, wherein- an optical sensor is used to monitor the pipeline, which is positioned in the pipeline or close to an outlet opening of the pipeline, and- the optical sensor recognizes a sand proportion in the sand-compressed air mixture, wherein the sand proportion forms a part of the sensor signal.

13. The method as claimed in claim 12, wherein based on the sensor signal of the optical sensor, the sanding monitoring unit recognizes the following states, namely: - when no sand is conducted via the pipeline,2024230211   31 Aug 202614.15.16.- when too much or too little sand is conducted via thepipeline, or- when sand is conducted with a correct proportion in thesand-compressed air mixture via the pipeline.The method as claimed in claim 9, wherein based on the sensor signal of the optical sensor, the sanding monitoring unit recognizes the following states, namely: - when no sand enters the wheel-rail gap,- when too much or too little sand enters the wheel-railgap, or- when the sand amount enters the wheel-rail gap next to therail.The method as claimed in any one of claims 9 to 14, wherein in the rail vehicle, each pipeline provided for sanding is monitored by a sensor.The method as claimed in any one of claims 9 to 15, wherein the sanding monitoring unit communicates with a control technology unit of the rail vehicle and / or with a fixed supervision office, in order to initiate measures in the event of a detected disturbance.

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