ARS products overview

  1. All Rail Systems           
  2. The importance of derailments
  3. The 3D&FAT Basic & Simplified System
    1. What is the 3D&FAT System and how does it work?
    2. What is the 3D&FAT System for and what does it provide?
    3. Where is the 3D&FAT System operating?
    4. Why to choose the 3D&FAT System?
    5. How does ARS implement the 3D&FAT System?
      1. Previous specific Study
      2. Examination and registration of parameters 'in situ'
      3. Dimensioning bells
      4. Montage and initial tests
      5. Training of personnel and maintenance of the 3D&FAT System
  4. The other versions of the 3D&FAT System
    1. DDD for Locomotives, 3D&FAT-LOC System
    2. DDD Electrical System, 3D&FAT-E
    3. DDD Economic System, 3D&FAT-ECO
  5. The 3D&FAT-SEL System, smart electronic locator derailed cars
1- All Rail Systems    


All Rail Systems, (ARS) is a Spanish company that manufactures and markets all variants of 3D&FAT System, for global rail sector. ARS has been in the market since 2002.

The company’s main objective is to provide high quality products to its clients, directed the immediate detection of derailments of trains, not only to minimize their financial losses, but also to save people’s lives. ARS are continuously looking to improve the products by inventing systems with new features that are easier to use.

ARS has professionals with extensive business experience and in railway, mechanical, electrical and electronic technologies, dedicated to the permanent innovation of its products: 3D&FAT (Basic), 3D&FAT-E (Electric), 3D&FAT -LOC (For locomotives).

All Rail Systems’ products are widely used in Europe, Africa and South America
2- The importance of derailments         

Since the beginning of the railroad, accidents caused by derailments have become a serious concern to transport operators and staff responsible for driving trains as well as users and society in general. The economic consequences of this type of accidents are huge; therefore, any approach to avoid or to minimize the losses is highly welcomed by the agents in charge of this important mode of transport. 

Transportation of dangerous goods such as chemicals, liquid fuels or nuclear waste, is getting increasingly unpopular and less tolerated by public, especially in countries or areas that suffer evacuations caused by railway accidents. In the USA, once a month on an average, evacuation of people happens caused by railway accidents that most of the times occur to a derailment.

The train drivers have great difficulties in detecting the moment when the derailment of the first bogie occurs and believe that if they could react quickly, most of the serious derailments could be prevented and turned into simple incidents. When there is no identification of that moment, the train speed remains unchanged. The risk of derailment spreading to other wagons grows proportionally to the time it takes to detect the phenomenon and subsequently stopping the convoy. In fact, sometimes derailments of multiple wagons happen suddenly, resulting in higher economic damage.

The need to reduce operating costs with better utilization of available resources, often results in creation of trains with several locomotives for traction, extending the length of the same significantly. In these circumstances when an axis is out of the way, the reaction caused due to fixing it, is even more difficult for the drivers to perceive, causing the train to run with derailed wagon for long distances.

When the affected track section has concrete railroad ties or sleepers which are more expensive than the traditional wooden ones, the incidence of economic damage significantly increases because often it is necessary to replace the entire damaged area. If the derailed wagon runs on areas where there are sidings like check-rails, diversions, needles, etc. or bridges or tunnels, it is likely that the derailment will spread to other wagons with consequent collapse of the whole train. Damage can also affect electric poles in the areas having them and can also lead to two-way collision with other units moving in the opposite direction, whether of freight or of passengers. 

ARS is specialized in the manufacture and commercialization of Devices Derailment Detectors, DDD

3- The 3D&FAT basic System, DDD mechanical-pneumatic  

3.1- What is the 3D&FAT System and how does it work?    

It is a system adaptable to any freight or passenger wagon provided with bogies, and has the ability to detect instantaneously the moment at which derailment occurs, causing immediate and automatic braking of the complete train. This system, which we call 3D&FAT, «Dispositivo Detector de Descarrilamiento Frenado Automático del Tren», has proven to be a really effective Derailment Detector D evice &  Automatic Braking of Train .

Originally it was invented and developed by FEVE, railway Spanish company today integrated to ADIF and RENFE. The initial prototype was improved, strengthened and adapted for its proper operation in adverse conditions, such as those that support railroads that travel through sandy deserts and with extreme temperatures.

Finally ARS has replaced the Automatic Brake Valve (VFA) with other one autopiloted (VRDR), which does not require any grafting or auxiliary pipeslines for the compressed air supply. This novelty developed by ARS and simplifying the 3D&FAT-Basic System has allowed the direct reduction of the sale price and, more importantly, the drastic reduction of assembly time and, definitively, the cheaper investment required for the Client.

The main feature of the 3D&FAT System is its absolutely geometric design, immune to vibrations and beatings, typical of systems based on inertial principles that use mechanical accelerometers, so it is able to detect derailments at any train speed, both in tracks with sleepers on ballast as in embedded rail into slab track. It is especially indicated when the infrastructures are not well preserved or very sinuous tracings exist. 

ARS considers that DDD systems based on inertial principles using mechanical accelerometers are applicable only to rail infrastructure with optimal condition of conservation. They are difficult to adjust because if they become sensitive to detect derailments at low speed, they cause false derailments in certain bumps and track devices, while if they tared with greater sensitivity they will not be able to act in real derailments at low speed of the embedded rail into slab track. The only evidence of the effectiveness of inertial systems was obtained in 2007, by a test organized by the University of Berlin at a speed of about 50 km/h. At lower speeds there is no concrete experience. The 3D&FAT has been operating in a fleet of more than two thousand cars for more 16 years, having acted in real derailments at very different speeds and circumstances, without false derailments 

The implementation of the DDD in a railway company is an important decision that gives rise to considerable technical and economic advantages. It does not prevent derailment which, unfortunately, is always and will be present in every railway vehicle, but if we obtain the detection at the moment when the exit of the first axle and immediately braking the train, we will prevent damage of economic consequences, sometimes disastrous. The 3D&FAT System, constitutes a very important contribution in favor of rail traffic safety, with evident capacity to improve the profits of the companies dedicated to this business.

The experience gained from the installation of the first device, suggests that equipment reliability is very high, covering most of the causes of derailment. Until today the system worked well in almost all cases and also, to the present, there has never been a delayed performance of the system in the prior occurrence of a derailment or a significant fault between the bogie and chassis car. 

In general terms, the 3D&FAT System is a mechanical and pneumatic device installed on each bogie. 

The mechanical part is made up of a specially designed pulsator, whose task is to examine the position of the bogie in relation to the wagon chassis or body, with respect to both its vertical axle (relative movement due to curves and the normal curving caused on straight sections) and the horizontal axle crossing the wagon (relative movements of the two bogie axles due to irregularities and bumps on the track).The mechanism is specifically sized for every type of bogie and track, certain tolerances being fixed in accordance with the minimum curve radius on the track, the maximum bumps and according to the type of suspension the wagon has. If these tolerances are exceeded, circumstance that only occurs when bogie derailment takes place, the longitudinal movement is transferred to the pulsator.

The pneumatic part, upon perceiving this movement, instantly transmits a pneumatic signal to an automatic Valve Relay of Rapid  Unload, VRDR, whose mission is to discharge the pressure of the TFA (Pipe of Automatic brake), for which,   the train complete receives the emergency braking order, and stop. The new automatic valve, VRDR, developed by ARS is autopiloted and does't need external air pressure, thus avoiding grafting as well as the laying of auxiliary pipes. See diagram:


In this video we explain, in 2 minutes, the operation of the 3D&FAT System. (in its version prior to the new VRDR):

3D&FAT All Rail System, *.flv

In this other video we can check, in half a minute, how 3D&FAT works:

3D&FAT All Rail System, *.flv

3.2- What is the 3D&FAT System for and what does it?  
The 3D&FAT system, as we have already stated, is used to reduce and minimise damage produced to infrastructure, rolling stock and the environment, following a derailment. It is not capable therefore of avoiding derailments, because it only acts after they have occurred.
The 3D&FAT system drastically reduces the damage caused in derailments by stopping the train in a few metres. Without this system, the train could continue for several kilometres with one or various wagons derailed, able to destroy everything in its path.

Listed below are some of the system’s most important contributions:

  • It reduces the risk of loss of human lives by minimizing the time the train is running with one or more derailed wagons.
  • It avoids multiple derailments, since it is able to start stopping the moment the derailment of the first bogie takes place, thereby avoiding greater damage.
  • The 3D&FAT system contributes in a large way to reducing risks in the transport of dangerous materials, such as chemical products and liquid fuels, leading to increased confidence among the people involved in it, from the train’s driver to customers, and without forgetting official bodies and society in general.
  • 3D&FAT adds to the railway company's prestige, improving its external image.
  • Hard to evaluate environmental damage is also reduced by using 3D&FAT.
  • Due to the reduced risk with 3D&FAT, it is possible to negotiate a reduction in premium with insurance companies.
  • It reduces traffic interruptions caused by derailments, improving turnover and service
  • Damage to freight caused by derailments is significantly reduced.

Entrepreneurs, responsible for transporting goods, on suffering the consequences of a serious derailment, wonder if it is wise to wait until the next derailment to take decisions. The existence of the 3D&FAT System allows them to have a new and powerful tool, in order to strengthen the passive safety of the trains and also significantly improve the financial results of their companies. 

3.3- Where is the 3D&FAT System operating?  
This system is operating successfully at the Spanish company «Ferrocarriles de Vía Estrecha» (Feve, today integrated in Adif-Renfe Spain), where currently, its entire freight wagon fleet, of about one thousand unit, uses it.
The 3D&FAT System operates in the entire fleet of EuskoKargo, brand name under which the public company of the Basque Government, Eusko Trenbideak-Ferrocarriles Vascos S.A., operates the rail freight transport.
The tourist train, Transcantábrico has installed the 3D&FAT System


In 'Ferrocarrils de la Generalitat de Catalunya' (FGC) we have carried out exhaustive tests verifying the absolute suitability of the 3D&FAT System for its fleet of hopper cars, used in the transport of potassium salts from the mines to the port of Barcelona.

In Mauritania, the National Industrial and Mining Company (SNIM), having a train operating in the Sahara desert, which is one of the heaviest and longest trains in the world, has installed the 3D&FAT system in its wagons. 

The ‘Ferrocarril Oriental de Bolivia’ and the ‘Yacimientos Petrolíferos Fiscales Bolivianos’ (YPFB), have wagons of load equipped with this same device

Our company, ARS, possessing this technological asset, offers 3D&FAT system to any railway company.


3.4- Why to choose the 3D&FAT system?   

The 3D&FAT system, conceptualized and created by railway workers for the railway, is characterized by:

  • As with all things that works well, this system is based on simple geometric principles.
  • It is not a prototype. It is a reality that operates with high reliability in several companies.
  • The basic system neither uses electrical conductors nor electronic devices. It does’t need batteries, accumulators or other analogical power sources.
  • It works well, independent of the speed at which derailment takes place.


    Detects derailments in any type of road, even in sections with embedded rail into slab track.
  • It is very simple to install, both in new as well as used wagons.


    It has a long useful life, similar to that of the freight wagons where it is installed.
  • Easy maintenance that does not require any lubrication, manually pushing the pulsator in periodic wagon inspections to check the system’s efficiency suffices.


    Following activation in a derailment, the system resets easily without using consumables of any type.
  • The average cost of the investment needed does not exceed 2% of the cost of a new wagon, the gross pay-back time being about 2 years, which is indicative of very high profitability.

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And remember: It is very difficult to avoid derailments, but with 3D&FAT it is very easy to reduce their damage.

3.5.  How does ARS implement the 3D&FAT System?    

 3.5.1. Previous specific Study   

We request the customer, through a tabulated questionnaire, data on their tracks and rolling stock, in order to acquire some prior knowledge of the main characteristics of the railway.

3.5.2. Examination and registration of parameters 'in situ'   

When DDD's installation is decided in a railway company and they don't realize tests adapted for it adjustment to the characteristics of the infrastructures and specific rolling stock, there's a risk of false derailments and, as a consequence, the demoralization so much of the personnel of driving as of the managerial structure. ARS is aware of this problem and therefore insists on the need to carry out a series of measures, records and tests with equipment specially designed for this mission.

Consequently, we programme the displacement, to the dependences of the client, of a technical team expert and specialized in the System 3D&FAT, for about 8-10 days, to realize 'in situ' dynamic analysis and record of the behavior and relative movements of the bogie with regard to the chassis, in a loaded and unloaded car, through a predetermined route. For such a mission we send in advance, measuring devices provided with the necessary elements, in order to register in a computer, such movements in three dimensions.

You can see   here, or in ANNEX 6.1,  the description of our SETELSA recording device

The results and corresponding analysis of the same, will be reflected in a report that is delivered to the Customer since it has practical application, very useful, for the Technical Services of Maintenance of tracks and rolling stock.  

 3.5.3. Dimensioning bells   

During the visit of the mentioned specialist team, and based on the recorded measurements, the bells are dimensioned and the necessary ones are fabricated for the first assembly in tests. For this operation personnel and means of the Customer's workshop are available, which follow the instructions of the personnel displaced by ARS.

3.5.4. Montage and initials test   

A first 3D&FAT kit is supplied, which will be mounted on a freight car or passenger coach, depending on the case. Following the assembly, tests are performed on load and empty operation in order to verify that there does not exist detection of false derailments. Later tests of derailments will be carried out to check the effectiveness of the system..

Later this car, or coach, will have to circulate, normally, by the customer's usual routes, to verify their behavior and, if necessary, make the final adjustments, prior to the delivery and assembly of the 3D&FAT on the remaining wagons. To such an effect and in order not to disturb ever the march of the train during these tests, ARS installs a Device Detector of False Derailments (DDFD), capable of registering on an electronic card SD such incidents, with date and hour, but without provoking stopped automatically of the train, during the duration of the same ones.

Once the test program has been successfully completed, the 3D&FAT Kits and bells can be manufactured and installed on the rest of the cars, with the certainty that there will be no false derailments and that the DDD will act when the unexpected derailment takes place, thus avoiding or mitigating damages on tracks and rolling stock, sometimes catastrophic.

You can see  here, or in ANNEX 6.2, the description of the False Derailment Detector Device (DDFD)

 3.5.5. Training of personnel and maintenance of the 3D&FAT System   

During the stay of the technical team in the customer's workshop, we take the opportunity for training the personnel involved in the 3D&FAT System, both regarding the assembly and maintenance as well as the operation of the same.

With the delivery of the order is included a Manual specifically made for each particular Client. With the documentation provided by ARS, sufficient information is available for monitoring and operating the System.

The 3D&FAT System does't require any greasings or maintenance and it is sufficient that in every preventive review of the car, or once for year, the following visual checks are realized:

  • The pipeline is not squashed or rubbed
  • That the pipeline support has not come untied or slackened.
  • That the centering and fastening of the detector device is in perfect condition.
  • That the bell actuator and its support are not offset or bent
  • The operation of the system will also be checked manually and observing that there are no leaks in the circuit. 

4. The other versions of the 3D&FAT System

4.1. DDD for Locomotives, 3D&FAT-LOC System    

Normally the locomotives do not require DDD, because when it derails one of them it is the own engineer that detects and reacts to him immediately, obtaining fast braking of the train. But when it comes to long compositions with 150, 200 or more cars, with several locomotives as it happens with mining trains, only one of them has driving personnel while the others operate automatically. In these cases the derailment of a locomotive without driving personnel, usually causes accidents of serious consequences. 

ARS has studied this matter proposing the adaptation of 3D&FAT to this particular situation. Although our DDD, in its normal assembly, is able to act by detecting vertical, horizontal and angular displacements of the bogie, in the case of the application in locomotives of three axes, it seems sufficient to only detect the vertical movement in each one of its axes. This means that when a axle loses wheel/rail contact, as in derailing, the vertical displacement of the bearing box will be considerably greater than normal displacements due to defects in the track and the locomotive's own dynamics. When a derailment occurs the compression and extension of the springs are translated in vertical movements that when detected by our 3D&FAT, they cause the automatic braking of the train.

Therefore, in order to dimension the actuator part, is mounted solidary by the box of bearing, it is necessary to carry out the analysis and registration of the vertical displacements of the bearing housing with respect to the bogie frame. The objective is to determine the normal displacements of the suspension so that the actuator part is designed with guarantees so that false derailments are not detected and, in case of real derailment, to guarantee that will be detected and the brake will be applied by total efficiency from the first instant, so that damage to track and rolling stock is reduced to a minimum.

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4.2. DDD Electrical System, 3D&FAT-E   

It’s the electric variant based on the same principle. It has a mechanical part similar to that described for the basic DDD but, when the derailment occurs, the motion transferred to the pulsator transmits an electrical signal, in place of pneumatic, to the brake control equipment of the train to cause the stoppage of the same automatically or manually, after warning the train driver. This results in a smoother braking than that obtained with emergency braking.

In this new 3D&FAT-E version, each wagon must have a power source, just like in EP (Electro Pneumatic Brakes) passenger trains and in freight trains equipped with ECPB (Electronically Controlled Pneumatic Brake Systems). This latter system is the most advanced and is present in long and heavy freight trains operating in Australia, South Africa, Brazil, USA and Canada and its advantages, among others, are reduced length of braking, less wear and tear in equipment and applying of brakes in all wagons simultaneously increasing the safety, efficiency and speed of trains.

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4.3. DDD Economic System, 3D&FAT-ECO   

It is a version that does’t take so many reliability as the one demonstrated by the System 3D&FAT Basic, because it can not act in some types of derailments and its adjustment for the prevention of false derailments is more difficult, but it has the advantage of being cheaper and easy to assemble.  

It is a variant of our DDD, also of geometric typology and inspired by other systems that they consist of arranging, for the detection of the derailment, of a steel cable surrounding each axis of the bogie. This cable is attached at one end to a specially designed steel part, which we call the fuse and is arranged so that, if the shaft derails, there is a probability that such a fuse will break due to the movements of the chassis with respect to the bogie.

The establishment of adequate clearance between cable and axle is very important and delicate. It must be sufficient in order that, in normal march, there are no wears for rubbing between both, but preventing the mentioned clearance from being excessive, because in such a case there will be less chance of action if there is little violent derailment. The montage and adjustment of the length of the cable is normally carried out with the car unloaded. Obviously the aforementioned clearance will be higher under load, depending on the compression suffered by the bogie suspension.


The swing of the chassis, especially when driving with the car unloaded and with tired suspension springs, can cause breakage of the steel fuse in some sinuous paths, without derailment causing untimely events or false derailments.

The fusible piece is bolted from the center to a bracket fixed to the car chassis. On one side is attached to the end of the cable while on the other, where it is drilled with blind hole, it is connected to a tube to the pressure of the TFA (Automatic Brake Pipe) The fuse piece is designed so that the section of rupture, when it occurs, allow the instantaneous evacuation of air.

The tubes of the four fuses of each car, one for each axis, are all connected between them and the Valve Relay of Rapid Unload, VRDR, using flexible pipes made of polyamide or steel, according to customer's choice.

The VRDR, which connects to the TFA through a Tea and a stopcock, is specially designed by ARS, and has a dual function:

  • One: The moment one or more of the fuses breaks, the air pressure drops inside the tubes and the relay valve opens automatically with a large discharge surface, causing the emergency stop of the complete train.
  • Two: The VRDR is autopiloted, ie when the system is reset, with the 4 fuses in place, it is the relay valve itself that feeds air and pressurizes the pipes where the four fuses are connected

The Valve Relay of Rapid Unload, VRDR, that ARS mounts with 3D&FAT-ECO is the same as the one we currently use in the Simplified 3D&FAT Basic System. The technical difference between both systems lies in the way of detecting derailment being more efficient and safe with the Basic system, as we have already mentioned.

See 3D&FAT-ECO operating scheme


5. The 3D&FAT-SEL System, the smart locator  electronic derailed cars   

When an episode of derailment is detected in short trains, for example with 20 cars, staff must look for the wagon or wagons that were affected. In order to do that manually they need to travel on foot to check the entire composition of the train: the cause of alarm, its consequences and they need to reset manually the affected device. The location and reset may take 10-15 minutes, during which the train is stopped, obstructing the traffic of other trains. However, when it comes to long compositions with 150, 200 or more wagons as with the miners trains, this type of episodes can provoke very long delays and supposes an important risk for the personnel, which must cross the route in search of the affected car, specially when there happen atmospheric adverse conditions or in night periods, because the length of the train can overcome two and up to three kilometres. For this reason it is very important to know immediately the place that occupies the car on which an anomaly or derailment has been detected.

In ARS we have developed an smart module very interesting, additional and complementary of the 3D&FAT system, which we call 3D&FAT-SEL (Location Electronically System) and is installed in each car. The new device is capable of receiving and transmitting data by radio, wirelessly communicating with adjacent cars. The set of all the cars, with the locomotive cab, forming a cascade network, WPAN (Wireless Personal Area Network), with the following features:

  • Each device or node, maintains the registration number of the corresponding car in his memory.
  • The cab of the locomotive has the primary node where the data transmitted by all the devices in the network, connecting interface touch to the driver, with the option to use several languages.
  • On command from the driver's cab of the train, auto-numbering of the position of each car, from first to last, takes place with respect to locomotive. While the train composition is not changed, this data is fixed in the primary device memory and on the display of the locomotive.
  • The wireless communication protocol used (ZigBee) ensures total integrity and reliability of the transmitted data. It is suitable for applications with low data rate, reasonable cost and has very low power consumption. This feature and the special design of the device allows the use of batteries that can last for several years without recharging.
  • When 3D&FAT it detects and stops the train for emptying of the TFA, as consequence of a derailment or mechanical failure, an alarm signal is received and transmitted by devices to other cars up to the cab of the locomotive, indicating the location of the car or cars affected by the derailment on the latter display.
  • Status information battery charging is also transmitted by recommending replacement or recharging when necessary.
  • Configuration module, consisting of a transmitter-receiver element, used to associate the device of each car with registration number by specific software is included.

Using GPS technology, the primary node located in the locomotive can collect data such as location of the derailment, locomotive’s speed record, personal driver of the train, serial number of the locomotive, etc. Data collected from all episodes that occurred during a particular route are sent to a Central Server via the railway company data communications mobile network (3G/GPRS)

ARS can supply software to Central Server with the following functions:

  • Ability to collect and store data for remote viewing in web interface and database for statistical analysis of incidences.
  • Web interface accessible in several languages, for access from any authorized and connected to internet, data of different trains and/or computer devices.
  • Filtering data for detailed analysis: device status, location and composition of train derailments histories, etc.
  • Grouping devices for end customers and geographies to facilitate analysis by filtering them in reports.
  • Graphical display of trains on Google Maps® .
  • Graphic information display derailments on Google Maps® .
  • Ability to export data for its interpretation to Microsoft Excel®, Matlab®, etc.
We present the pneumatic scheme that interconnects 3D&FAT and 3D&FAT-SEL

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6. ANNEXES (next pages, in Spanish)    

6.1 Description of the SETELSA Recording Device

6.2  Schemes of:   3D&FAT Basic Simplified and 3D&FAT-ECO, Economic  





The 3D&FATreduces traffic interruptions caused by derailments, improving turnover and service and damage to freight caused by derailments is significantly reduced.


The 3D&FAT Systems avoids multiple derailments, since it is able to start stopping the moment the derailment of the first bogie takes place, thereby avoiding greater damage.

Reduce y minimiza

The 3D&FAT reduces the risk of loss of human lives by minimizing the time the train is running with one or various cars derailed

  • New!
    With VDRD
    the 3D&FAT is

    Avec VDRD le
    3D&FAT est

    Con la VRDR
    el 3D&FAT
    se simplifica

  • It's very difficult to
    avoid derailments

    But with 3D&FAT

    It's very easy to reduce

    their catastrophic effects

  •   The 3D&FAT Systems, also for passenger trains  

  •                            NEW! The 3D&FAT-SEL is the smart locator of derailed cars 

  • '''ccccc


    DDD for Locomotives!

    • Simple
    • Economic
    • Reliable

    3D&FAT System

    Safety and efficiency

    Derailment Detector Device (DDD) 

    and Braking Automatic Train

    Drastically reduces damage derailment

  • 3D&FAT System                                                                                  

    The best and most efficient DDD

    • Prevents disasters
    • Reduce economic damage
    • Reliable at any speed