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Patrick Fitzgerald -
Posted 2 years ago

WiFi for Train Communications

Communication Systems

  WiFi for Train Communications   WiFi can be used to communicate with moving trains in a metro system. Ordinary WiFi like in my home? Could be.  IEEE802.11g 2.4GHz band, like you use in your home.  But the 5.8-5.9GHz band using 802.11a or 802.11n has certain advantages. There is even an 802.11p available but I think that is reserved for trucking.   http://standards.ieee.org/about/get/802/802.11.html By using WiFi in the 5.8-5.9GHz band you can go to higher power EIRP.  http://en.wikipedia.org/wiki/U-NII  shows this spectrum for 802.11a in the United States.  Most countries, Canada, Europe, Saudi Arabia, etc. will more-or-less follow this spectrum;  perhaps with blocks reserved or different maximum powers. When you want your WiFi access points spread out along the guideway, power determines how close or how far apart your wayside access points can be located.  According to  http://en.wikipedia.org/wiki/U-NII  you can go up to 4Watts=36dBm in the USA. Trains move, fast.  A higher power allows you to space out your Wayside Access points.  100 or 200m being typical.  If the train had to perform a complete logon for every change of access point more time would be spent authenticating than transferring data.  A wireless access controller can reduce time wasted.    http://www.youtube.com/watch?v=0n-uIusTpU8 Finally, everybody has a device that can affect the 2.4GHz range. Laptops, smartphones.  By going to the 5.8-5.9GHz band a cyber-intruder needs to have a wifi device that can work in that "exotic" range. What is in the data? Train position, train speed, commands to stop, commands to go, status and health of train electronics and mechanical equipment, perhaps even who is logged in as driver.  Each manufacturer:  Thales, AnsaldoSTS, Siemens, Bombardier, to name just a few, will have their own proprietary messaging and their own way of doing things for CBTC communications based train control.  But they all have the same goal of moving trains, or stopping trains, without the nuisance of the trains hitting each other. Any WiFi link carrying ATC or CBTC data must be secured.  WPA encryption is only the beginning.  Authentication with passkey and MAC address control are needed, as well.  By writing the CBTC protocol to conform to IEC EN 50159 the actual data messages will be encrypted, again, authenticated and they must make sense to the CBTC servers and clients or they will be rejected.  Any lost messages must be detected and re-transmitted. Just like your home WiFi the SSID beacon can be suppressed.  The train knows what network to connect to and it's not like railway tracks move around a lot.   What else is special about WiFi for Metro Trains Rail alignments are long and skinny. By using a directional antenna you amplify the signal along the track and reduce the waste of power going to the sides. 12-15-18 dBi are common antenna gains. EIRP is the total power put into the antenna, directional gain means the receiver will receive a greater portion of that power. On board the train are many systems using open protocols. To talk to doors, HVAC, break systems you will commonly encounter CANBus, MVB or TWN standards. A voice circuit is needed for a manual operator, a SoftPhone using a VoIP client can connect through the WiFi network along with the ATC, ATS and ATO protocols.   image from researchgate.net

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Joanie Zhao -
Posted 9 months ago

Why you need a railway concrete sleeper bolt drilling machine?

Rail Infrastructure

The Railway Concrete Sleeper Bolt Drilling Machine plays a crucial role in railway maintenance work, offering several important benefits. Here are some key points highlighting its significance: Precision and accuracy: Railway tracks require secure fastening to ensure stability and safety. The bolt drilling machine provides exceptional precision and accuracy when drilling bolt holes in concrete sleepers. This ensures that the bolts fit perfectly, preventing any potential issues or hazards caused by loose or misaligned tracks. Time and labor savings: Manual drilling of bolt holes in concrete sleepers is a labor-intensive and time-consuming process. The bolt drilling machine significantly reduces the time and effort required for this task. It automates the drilling process, enabling faster completion of railway maintenance projects and reducing labor costs. Consistency and quality: Maintaining consistent quality across all bolt holes is essential for the overall integrity of the railway tracks. The machine ensures uniform drilling depth and diameter, eliminating variations that can compromise the structural stability of the tracks. This consistent and high-quality fastening enhances the overall reliability and longevity of the railway system. Increased productivity: The efficiency of the bolt drilling machine allows railway maintenance crews to accomplish more work in less time. With its high drilling speed and capacity, the machine can handle a large volume of drilling tasks, contributing to increased productivity and project throughput. Versatility and adaptability: Railway networks often have different sleeper sizes and designs. The bolt drilling machine is designed to be versatile and adaptable, capable of accommodating various sleeper specifications. This flexibility makes it suitable for a wide range of railway maintenance projects, regardless of the specific track configuration. Enhanced safety: Railway maintenance work involves potential hazards, and the bolt drilling machine incorporates safety features to protect operators. These may include safety guards, emergency stop buttons, and ergonomic designs to minimize operator fatigue and reduce the risk of accidents during operation. Longevity and durability: Railway infrastructure requires long-lasting solutions. The bolt drilling machine is constructed with robust materials and engineered to withstand the demanding conditions of railway maintenance work. Its durability ensures reliable performance over an extended period, reducing maintenance and replacement costs.

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Joanie Zhao -
Posted 7 months ago

Why we say the rail wear gauge is significant importance in rail maintenance?

Rail Infrastructure

1) Safety: Rail wear gauges help ensure the safety of train operations. By measuring the wear of the railhead, maintenance personnel can identify areas where the rail may have worn beyond acceptable limits. Excessive rail wear can lead to reduced track stability, increased risk of derailments, and compromised train operations. Regular use of rail wear gauges allows maintenance teams to identify worn sections promptly and take appropriate action to maintain safe track conditions. 2) Maintenance Planning: Rail wear gauges play a crucial role in maintenance planning. By accurately measuring the wear of the railhead, maintenance teams can determine the remaining lifespan of the rail before replacement or major repairs are necessary. This information enables them to schedule maintenance activities proactively, minimizing disruptions to train services and optimizing maintenance resources. 3) Cost Efficiency: Rail wear gauges contribute to cost-effective rail maintenance. By monitoring rail wear regularly, maintenance teams can identify sections that require corrective actions, such as grinding or milling, to restore the desired rail profile. Targeted maintenance based on wear measurements allows for efficient utilization of resources, reducing unnecessary maintenance interventions and optimizing the rail's service life. 4) Track Performance: Rail wear gauges provide valuable insights into the performance of the track. By analyzing wear patterns across the rail network, maintenance teams can identify areas of accelerated wear, which may be indicative of underlying issues such as misalignment, excessive loading, or substandard maintenance practices. This information helps in identifying root causes and implementing corrective measures to improve track performance and longevity. 5) Regulatory Compliance: Rail wear gauges are essential for compliance with regulatory standards and requirements. Rail networks are subject to specific wear limits and profiles mandated by regulatory bodies. By using rail wear gauges, maintenance teams can ensure that the railhead wear remains within acceptable limits, complying with the prescribed standards and minimizing the risk of non-compliance penalties. Joanie Mob./Whatsapp:008615015909102 Email:  inquiry@linkagetrack.com

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Joanie Zhao -
Posted 9 months ago

Why do regular ballast bed tamping work insist on small tamping machine?

Rail Infrastructure

Regular ballast bed tamping work often involves manual labor for several reasons: Flexibility and Adaptability: Manual work allows the tamping crew to assess the condition of the ballast bed and make real-time adjustments based on their expertise. They can identify specific areas that require additional or less compaction and adjust the intensity and direction of the tamper accordingly. Manual work enables the crew to adapt to varying conditions, such as changes in the ballast quality or track geometry. Precision and Control: Manual tamping provides a higher level of precision and control compared to automated or mechanical methods. Experienced workers can apply the right amount of force and distribute it evenly, ensuring proper compaction of the ballast bed. They can also detect any irregularities, such as soft spots or voids, and address them promptly. Safety Considerations: Manual tamping allows workers to visually inspect the ballast bed and identify any potential safety hazards, such as loose fastenings, damaged sleepers, or track misalignments. These issues can be addressed immediately, reducing the risk of accidents or derailments. Manual work also enables workers to maintain a safe distance from moving trains and machinery, ensuring their safety during the tamping process. Cost Considerations: Manual tamping is often more cost-effective, especially for smaller maintenance projects or locations with limited access for machinery. Automated or mechanical methods may require significant investment in specialized equipment, which may not be economically feasible for every project. Manual tamping can be performed with basic hand tools and a smaller crew, reducing equipment costs and operational expenses. While manual tamping work has its advantages, it is worth noting that the railway industry is constantly evolving, and there are automated and semi-automated solutions available for ballast tamping. These technologies aim to enhance efficiency, accuracy, and productivity while reducing physical labor. However, the decision to adopt such methods depends on various factors, including the project scale, budget, and specific requirements of the railway network.   More Rail tamping solutions please contact 008615015909102  email: inquiry@linkagetrack.com

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Joanie Zhao -
Posted 4 months ago

which problem do you meet when using rail drilling machines? How should it be solved?

Rail Infrastructure

As the production automation continues to improve, the application of Rail drilling machines is rapidly expanding, the variety and specifications of products continue to increase, performance and quality are constantly improving, and the market sales output value is also growing steadily. So which problem do you meet when using rail drilling machines? How should it be solved? 1.Breakage of the tap of the drilling machine: Solution: When the tap of the drilling machine breaks, the diameter of the threaded bottom hole must be correctly selected; the inclination of the sharpening edge or the selected spiral groove tap should be used, and the depth of the drilled bottom hole must meet the specified standards; Appropriately reduce the cutting speed and select according to the standard; correct the tap and the bottom hole when tapping to ensure that their coaxiality meets the requirements, and select a floating tapping chuck; increase the tap rake angle and shorten the cutting cone length; ensure that the workpiece hardness meets the requirements , choose a safety chuck; if the tap is worn, it should be replaced in time. 2. Tap chipping; solution: tap chipping reduces the rake angle of the tap appropriately; increases the length of the cutting cone appropriately; reduces the hardness and replace the tap in time. If the tap wears too fast, reduce the cutting speed appropriately; reduce the tap rake angle and lengthen the length of the cutting cone; choose a cutting fluid with good lubricity; perform appropriate heat treatment on the workpiece; and sharpen the tap correctly. 3. The pitch diameter of the thread is too large; Solution: The pitch diameter of the thread is too large. Choose a tap pitch diameter with a reasonable accuracy level; select the appropriate cutting fluid and appropriately reduce the cutting speed; correct the coaxiality of the tap and the thread bottom hole when tapping. Use a floating chuck; appropriately reduce the rake angle and cutting cone relief angle; remove the burrs produced by sharpening taps, and appropriately increase the cutting cone length. 4. The thread pitch diameter is too small; Solution: If the thread pitch diameter is too small, choose a tap pitch diameter suitable for the accuracy level; appropriately increase the tap rake angle and cutting taper angle; replace the tap that is too worn; the automatic tapping machine should be lubricated Good cutting fluid. 5. The thread surface roughness value is too large; solution: the thread surface roughness value is too large, appropriately increase the tap rake angle and reduce the cutting taper angle; perform heat treatment, appropriately increase the hardness of the workpiece, and ensure that the tap rake surface has a lower surface Choose a cutting fluid with good lubrication for the roughness value; reduce the cutting speed appropriately; replace worn taps for the automatic tapping machine. #Rail #drilling #machine #equipment #problem #solve

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Joanie Zhao -
Posted 5 months ago

What's the reason of the train doesn't derail?

Rail Infrastructure

As a unique means of transportation, the biggest difference between trains and other land vehicles is probably the part in contact with the ground. Cars mainly use rubber, a material with high friction and elasticity, to make tires, but trains cannot be made with wheels. They also need the cooperation of rails to operate normally. But we can see that the wheels of the train press forward on the thin rails, but there are very few derailment accidents. Why is this? The wheel of a train looks like a cylinder on the outside with a slightly larger "disc" on the inside. Many people think that the disc on the inside is what fixes the wheels and rails. In fact, this is not the case at all. After all, if part of the disc contacts the rails for a long time, the friction will inevitably increase significantly and affect the speed of the train. Therefore, the existence of this disk can be said to be an "insurance", which can only play its role in critical moments. The key is that the "cylinder" on the outside is actually a cone, or a truncated cone to be precise. A simple cylinder will obviously not be able to keep moving in parallel on a smooth rail surface, but if there is an inclined surface, it will be different. Even when turning, the balance of the tires on both sides can be maintained. So on the surface it seems that the connection between the train and the rails is not close, but in fact the train stays on the rails in a very stable manner. Furthermore, the weight of the train itself has reached a certain level, so it will not be unstable because it is too light, and of course it will not be unable to speed up because it is too heavy. Therefore, the train track may seem to have a simple structure, but in fact it contains many mechanical principles to ensure that the train does not derail. "Learning" on the Rails In addition to the train itself, the rails of the train are obviously also an extremely important part of transportation. Without suitable rails, the train will be unable to move. We know that in addition to the two basic rails, sleepers and ballast are also indispensable parts of railway tracks. The sleeper has many functions. It plays the role of connecting two rails, dispersing the huge pressure of the train pressing on the rails and transmitting it to the roadbed below. Because the sleepers will deform to a certain extent when the train passes by, the material of the sleepers needs to be both soft and tough. As for the role of ballast, it is mainly to buffer the pressure received by the sleepers and increase the life of the track. In addition, the drainage function provided by the gravel is also very important, which can allow rainwater to be discharged in time without greatly reducing the friction between the wheels and the track, thus increasing the safety of train driving and ensuring that it can operate under various climatic conditions,safety.

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Nabayan Datta -
Posted one year ago

Weight of Indian Railways

Rollingstock

Transport business are based on four basic pillar 'QDDS' of Quantity (Q) to transport, Distance (D) to transport, Duration (D) of transport and sort of Services (S) facilitated by transporter to their customers. In this topic, will discuss about the point Q which is reckoned as the most crucial point for any transportation mode. In India, we have four different mode of transportation to serve the nation inwardly i.e. Surface mode, Railway mode, Airways mode and Inland waterways mode. All of those have their different modal share among transport sector to carry out Passengers and different kind of Goods. In this context, we can definitely says that railway carries the highest tonnage than any other transporter in every financial year. Indian railways carries 1246 kind of goods in 365 type of stocks. Among them Open stocks and Jumbo stocks has highest utilisation index. Every stocks has different kind of characteristics and specifications in terms of weight carrying capacity. Before going to discuss technical & mathematical aspect of it, want to through some light on how quantity are correlated with distance and make GTKM, NTKM like productivity index.    Tonnage Kilometres          At first we should clear the concept of TKM or Tonnage Kilometers index using in railway statistics. What is TKM? TKM is a fundamental unit to express the mobility and loading capacity of a single unit on account of revenue earning work. In other language, how much quantity? For how much distance? lets break the confusion by illustrating this. In 24 hours span, 59 BOXN carried 4179 MT Coal for 300 Kilometers and a 42 BCN carried 2500 MT Food grains for 120 Kilometers. What will be the Gross and Net Kilometres earned by those stocks in 24 hours span? We all have a rooted perception about gross and net is, Inclusiveness means gross and Exclusiveness means net. What are need to exclude to get the net? A locomotive and Some stocks to creates a train. So when we exclude the weight of locomotive and tare weight of wagon, we will get net figure. As per the above mentioned example NTKM of 59 BOXN will be 4179*300=1253700 and of 42 BCN will be 2500*120=300000. This is how distance are correlated with quantity in transportation fields.    Pay to Tare Ratio and Revenue earning We have a transport company, we have some carriers to move out goods. Let, you placed a indent of some goods weighted 50 k.g but our carrier weighted 18 k.g and they can carry only 40 k.g. therefore, the Pay to Tare Ratio of that carrier will be 40k.g/18k.g = 2.2 or 11:5 means if there was 16 total proportion, 11% can be filled with goods against 5% tare load. If the difference between net weight and dead weight are in increasing nature, it meant to be economical growth of the organisation. The low tare load of railway wagons is significant not only to produces the possibility of carrying a higher payload but also increases the energy consumption per payload tonne hauled. One way to reduce the energy consumption per tonne payload is to reduce the tare load. One possibility of lowering the tare load is to reduce the number of components such as a bolster, sideframes, and axles. To take advantage of the lower tare mass, a new concept wagon was conceptualised as a wagon with maximum axle load and with enough load space to ensure a higher tonne gross load. More you can lower dead weight, the more you can carry goods. In IR, currently BOXNS is such a wagon which have the most effective pay to tare ratio with 4.2 or 21:5   Carrying Capacity               Our railway system are in forth position in terms of freight movement. IR loaded 1400+ million tonne of goods in F.Y 21-22 including bulk, break bulk and non-bulk commodities, built light tare wagons, built HHP locos to drag and strengthen their routes to carry effective load. If we notice IR has 4 types of route in terms of carrying capacity. We saw there was a progressive revolution. BG route was started with maximum 22t. Axle load carrying capacity, also called as Excepted CC+6 route then it was extended by 0.4 and made up 22.4t. Axle route also called Universal CC+6 route. Then CC+8 or 22.09t. axle route comes into force. Most of the IR routes are now fitted with 22.09 axle loading capacity but several years ago IR upgraded their 1st 334 k.m long iron ore EXIM route BSPX to PRDP via JKPR into 25t. axle route. After this, almost all iron ore dominating routes of SER, SECR, ECoR and SWR became 25t. axle route. As a result india ranks 4th in iron ore exporting. In this context a question may be arise in mind that despite the highest loaded commodity why coal routes are not universally 25t. axle loading fitted? Probable answer may be given geographically as well as statistically. All soil region of the country are not tough enough as compared to Chottanagpur domain. When a 5800 to 5900t. loaded rake run through 75-80 k.m/hrs it lefts immense impact on soil and track and statistically IR has not enough 25t. axle stock for consequent 25t. coal loading. Thats why at present, 25t. axle loading is permissible only for iron ore in specified routes. Maximum how many tonnage of goods can be loaded in a wagon? This limitation varies on two factor, Carrying Capacity of indented wagon and Carrying Capacity of booked route to reach destination. Wagon CC is a constant index, where Route CC or Permissible Carrying Capacity (PCC) is a variable in accordance with  A. Various route wise  B. Various commodity wise  C. Session wise.  Whenever a consignment booked via more than one type of route i.e Expected CC+6, Universal CC+6, CC+8 and Iron ore route, the permissible weight will be as same as the most restrictive route. Why the commodity factor is discernible in times of wagon loading? IR has sets the commodity wise PCC variety, keeping in mind the significance of agriculture sector, industrial sector, Salt-Sugar like two essential consumable, Food grains and others:-                  1) At the top, Raw materials for plants and Agricultural product had been patronised as Raw materials is a basic factor in making decisions on the establishment of building-material production plants, regardless of the scale of production and Agriculture can be important for developing countries in several ways, where food security is weak it can be a vital source of nutrition, it provides income for farmers and farm workers and thus revenues for rural areas, job opportunities in related areas such as processing and in some cases export revenue.  2) At second, Sugar & Salt commodities that drove the world. For millenia, religion, commerce, war, health, and gold were tied to little white crystals. In the beginning animals wore paths, looking for salt licks, men followed, trails became roads, settlements grew beside them. Scarcity kept salt precious and as civilization spread, two became one of the world’s principal trading commodities.  3) At third, Food grains. Healthy people are assets, they live longer, they should be more productive, and their existence may not be associated with misery and liability. Therefore, national development is incomplete without a healthy population, which accounts for national productivity. That's why healthy food grains that meets food preferences and dietary needs for an active and healthy life.  4) Others commodity except above mentioned commodity head which IR used to carry has the least PCC ever.  IR has also a provision to set PCC session wise. The PCC for carrying coal during monsoon period i.e. 1st July to 15th August when loaded on CC+8 route, shall be 1 tonne less than usual.    Empty Weighment of rakes For instance, in railways weight of loose bulk commodities are determined by deducting the designed tare weight of all wagons (without actually weighing them) from the gross weight of the rake. Railway assume the sum total of designed tare weight of wagons to be the actual tare weight of rake. The designed tare weight of wagons may not be remain same and there is high chance to increase during the course of various overhauling. That is why actual tare weight of rakes should be verify by weighing them in empty condition after a certain periods.   Last word Now a days, overloading by violating PCC beyond tollerance limit is a common scenrrio over IR. Loads are getting originated unweighted under SWA (Sender's Weight Accepted) upto first available motion weighbridge and founded huge overweighted. As per commercial manual V-2 of IR, though there was a provision of collecting overloading charges, but it is not about revenue earnings at all. Railways have permitted the running of trains loaded with enhanced quantity without complying with the conditions laid down for protecting track and rolling stock. Even after permitting loading of wagons with enhanced quantity, the trend of overloading continued. Increased incidence of rail fractures, weld fractures and defects in wagons and locomotives was seen. Such practice should be stopped.      

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Suman Pathak -
Posted 2 years ago

Various Systems of Railway Electrification

Rail Electrification

Various Systems of Railway Electrification Several different types of Railway Traction Electric Power System configurations have been used all over the World. The choice of the system depends on the train service requirements such as  I.    Commuter rail  -Commuter rail typically includes one to two stops per city/town/suburb along a greater rail corridor II.    Freight rail -Rail freight transport is the usage of railroads and trains to transport cargo on land. It can be used for transporting various kinds of goods III.    Light rail -The LRT vehicles usually consist of 2–3 cars operating at an average speed of 55–60 km/h on the lines with more dense stops/stations and 65–70 km/h along the lines with less dense stations IV.    Train load s V.    Electric utility power supply. Railway electrification loads and systems required for light rails, commuter trains, fast high-speed trains, and of course the freight trains are all different. The power demands for these different rail systems are very different. The selection of an appropriate electrification system is therefore very dependent on the Railway system objectives Presently, the following four types of track electrification systems are available: 1. Direct current system—600 V, 750 V, 1500 V, 3000 V  2. Single-phase ac system—15-25 kV, 16 23, 25 and 50 Hz  3. Three-phase ac system—3000-3500 V at 16 2 3 Hz  4. Composite system—involving conversion of single-phase ac into 3-phase ac or dc.   Direct Current Traction System In this traction system, electrical motors are operating on DC supply to produce the necessary movement of the vehicle. Mostly DC series motors are used in this system. For tramways, DC compound motors are used where regenerative braking is required. Regenerative braking   In this type of braking the motor is not disconnected from the supply but remains connected to it and feeds back the braking energy or its kinetic energy to the supply system. The essential condition for this is that the induced emf should be slightly more than the supply voltage.  The various operating voltages of the DC traction system include 600V, 750 V, 1500V, and 3000V. •    DC supply at 600-750V is universally employed for tramways and light metros in urban areas and for many suburban areas. This supply is obtained from a third rail or conductor rail, which involves very large currents. •    DC supply at 1500- 3000 is used for mainline services such as light and heavy metros. This supply is drawn mostly from an overhead line system that involves small currents. Since in the majority of cases, track (or running) rails are used as the return conductor, only one conductor rail is required. Both these supply voltages are fed from substations which are located 3-5 KM for suburban services and 40 to 50KMs for mainline services. These substations receive power (typically, 110/132 KV, 3 phase) from electric power grids. This three-phase high voltage is stepped-down and converted into single-phase low voltage using Scott-connected three phase transformers. This single-phase low voltage is then converted into DC voltage using suitable converters or rectifiers. The DC supply is then applied to the DC motor via a suitable contact system and additional circuitry.   Advantages 1. In the case of heavy trains that require frequent and rapid accelerations, DC traction motors are the better choice as compared to AC motors. 2. DC train consumes less energy compared to AC unit for operating same service conditions. 3. The equipment in the DC traction system is less costly, lighter, and more efficient than the AC traction system. 4. It causes no electrical interference with nearby communication lines. Disadvantages 1. Expensive substations are required at frequent intervals. 2. The overhead wire or third rail must be relatively large and heavy. 3. Voltage goes on decreasing with an increase in length.                 Single-phase ac system In this type of traction system, AC series motors are used to produce the necessary movement of the vehicle. This supply is taken from a single overhead conductor with the running rails. A pantograph collector is used for this purpose. The supply is transferred to the primary of the transformer through an oil circuit breaker. The secondary of the transformer is connected to the motor through switchgear connected to suitable tapping on the secondary winding of the transformer. The switching equipment may be mechanically operated tapping switch or remote-controlled contractor of group switches. The switching connections are arranged in two groups usually connected to the ends of a double choke coil which lies between the collections to adjacent tapping points on the transformer. Thus, the coil acts as a preventive coil to enable tapping change to be made without short-circuiting sections of the transformer winding and without the necessity of opening the main circuit.  Out of various AC systems like 15-25 kV, 16 23, 25, and 50 Hz. Mostly the 25KV voltage is used in railways. The main reason for the 25kV voltage used in the railway is, that 25 kV AC is more economical than a 1.5kV DC voltage system. Since the 25kV voltage system has a higher voltage, the higher voltage reduces the current flow through the conductor; this reflects reducing the conductor size. The cost of the conductor gets less.  However, there are other major advantages for using 25kV voltage system in railway are quick availability and generation of AC that can be easily stepped up or down, easy controlling of AC motors, a smaller number of substations requirement, and the presence of light overhead catenaries that transfer low currents at high voltages, and so on.   Disadvantages 1.  Significant cost of electrification. 2.  Increased maintenance cost of lines. 3.  Upgrading needs additional cost especially in case there are bridges and tunnels. Composite System As the name suggests this system is classified into two types  I single phase to dc system II single phases to 3 phase system Single Phase to DC system The first one single phase to dc system is used where the voltage level is high for transmission and the dc machine is used in the locomotive. This system combines the advantages of high-voltage ac distribution at the industrial frequency with the dc series motors traction. It employs an overhead 25-kV, 50-Hz supply which is stepped down by the transformer installed in the locomotive itself. The low-voltage ac supply is then converted into dc supply by the rectifier which is also carried on the locomotive. This dc supply is finally fed to dc series traction motor fitted between the wheels.                                                                                     Single-phase to 3 phase system Single-phase to 3 phase system is used where 3 phase machine is used in the locomotive and Single-phase track available. In this system, the single-phase 16KV, 50 Hz supply from the sub-station is picked up by the locomotive through the single overhead contact wire. It is then converted into a 3-phase AC supply at the same frequency by means of phase converter equipment carried on the locomotives. This 3-phase supply is then fed to the 3-phase induction motor. References: various EMC Europe IEEE papers, slideshare.net presentations, rail systems, etc.

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Joanie Zhao -
Posted 9 months ago

The main tools for track inspection and maintenance

Rail Tracks

The geometric size and structure of the track are important criteria for detecting whether the track is in good condition. The gauge, level, direction, height and other basic elements of the existing line track are mainly measured with gauge ruler and string rope, and T-shaped crutches, crowbars, hydraulic track lifters, etc. are used for renovation work, and the required tools are complicated. A lot of renovation work. Mechanical track gauge Digital track gauge Track turner Hydraulic track lifting machine Hydraulic Rail Adjuster  

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Joanie Zhao -
Posted 9 months ago

The importance of rail measuring equipment

Rail Infrastructure

Rail measuring equipment plays a crucial role in ensuring the safety, efficiency, and reliability of railway systems. These tools are specifically designed to measure and assess various aspects of railway tracks, including their geometry, alignment, and condition. Here are some key reasons why rail measuring equipment is important: Safety: The safety of railway operations is of paramount importance. Rail measuring equipment helps identify and rectify track irregularities such as uneven gauge, track misalignment, and deviations from the desired track geometry. By detecting and correcting these issues promptly, rail measuring equipment contributes to maintaining safe operating conditions for trains, reducing the risk of derailments and accidents. Track maintenance: Regular maintenance of railway tracks is essential to ensure smooth and reliable train operations. Rail measuring equipment provides accurate data on the condition of tracks, including parameters like rail wear, corrugation, and defects. This information helps railway maintenance teams identify areas that require repair or replacement, allowing them to proactively address potential issues before they escalate and disrupt train services. Infrastructure optimization: Rail measuring equipment enables detailed measurements and assessments of track geometry, such as track gauge, alignment, and curvature. This data is crucial for optimizing the railway infrastructure, improving track layouts, reducing wear and tear on rails and wheels, and maximizing operational efficiency. By identifying areas for optimization, rail measuring equipment helps minimize maintenance costs, reduce energy consumption, and enhance overall system performance. Compliance with standards: Railway tracks must comply with specific standards and regulations to ensure operational safety and compatibility with rolling stock. Rail measuring equipment helps verify whether tracks meet the required standards, allowing railway authorities to identify non-compliant sections and take corrective actions. This ensures that the infrastructure remains in line with industry regulations and guidelines. Data-driven decision-making: Rail measuring equipment generates precise and detailed data about track conditions, which can be analyzed to make informed decisions. By collecting and analyzing this data, railway operators can develop predictive maintenance strategies, optimize inspection schedules, and allocate resources effectively. Data-driven decision-making helps enhance the overall efficiency and reliability of railway systems. Wuhan Linkage Track Equipment manufacture are reliable railway measuring solutions supplier, more detail contact Mob./Whatsapp/Wechat: 008615015909102 or email inquiry@linkagetrack.com

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Andree Litaay -
Posted 2 years ago

Terminology Go and No Go Test of Switch Machine

Signalling

  TERMINOLOGY GO AND NO GO TEST OF SWITCH MACHINE Go and No Go test or obstruction test always be performed to finalize of point machine installation and point machine maintenance. The purposes of this test to ensure that switch machine on safe condition and ready to use. During train operation or switch machine operation for testing purpose, switch machine failure might be occured. To solve this failure, adjusment on driving rod, detection rod or back drive (if any) are required. Due to those adjustment before switch machine will to use for train operation or testing purposes then Go and No Go test shall be performed. The value of shim to perform this test is depend on the regulation of railway authority in each country or project. For example, in LRT Jabodebek Indonesia Project using 2mm for Go and 4 mm for No Go, PT. KAI (Indoneisa Railway Authority) for subway operation using 3 mm for Go and 5 mm for No Go and KTMB Berhad (Malaysia Railway Authority) at Seremban Gemas Double Track Project and Johor Bahru Sentral Project using 1.5 mm for Go and 2 mm for No Go. To explain about the terminology Go and No Go Test  of switch machine more detail, much better start from analyse the sequences of switch machine operation, refer to a book Railway Signalling  Edited by O.S. Nock , First Published 1980 ©1980 Institution of  Railway  Signal Engineer, on Page 98 with sub-title  “The sequence of operations in power working is therefore” : 1. Unlock the point, by withdrawal of the lock plunger from the srecher bar, nothing that immediatly the lock plunger begins to move the point and lock detection circuit is disconnected. Explanation : Release Locking switch machine and detection. Train operator throw switch machine from LCP or VDU by enforce throw or route set then electric motor will drive the lever to release locking of switch machine and immediatly release locking of detection. It was applied for all of type switch machine. Every switch machine has own type of  driver lever locking (Internal locking and External locking). And the detection also has a two type (Intenal Detection and External Detection). If switch machine cannot perform this step, its could be has a problem with installation. Following below is failure on this step : Electrical Failure     : Fuse was burn out (AC circuit), Bad contact(AC circuit), wiring mismatch, Drop in AC voltage, Motor phase                                      in-balance. Construction failure : Deformation in the switch blades, The levelling of track mismatch, Bad sitting of switch blades to the base                                        plate. Mechanical Failures : Driving rod misalignment, Installation of  back drive too wide (if any).   2. The point are driven across from normal to reverse , or vice versa. Explanation : Switch machine driven  the switch blade through the driving rod from Normal postion to Reverse position  or vice versa until to the new position. On this step the important thing is checking the movement. The movement of switch blade shall be smooth. If any hard movement that indicated has a problem. Following below is failure on this step : Electrical Failure       : Motor phase in-balance, Drop in AC Voltage. Construction Failure : The levelling of track mismatch, Bad sitting of switch blades to the base plate. Mechanical Failure   : Not enough lubrication on the teack element and switch machine.   3. The points are locked in their new position, the last movement of  the locking plunger completing the detection circuit in the new position. Explanation : Switch blade was locked at the new position then the locking detection will re-locked as well. Following below indication of switch machine operation was successful : Switch blade close properly. The opening switch blade has followed the specific value. Switch machine has locking properly. Get position detection. Following below is failure on this step : Electrical Failure       : Fuse was burn out (DC circuit),  Bad contact(DC circuit), wiring mismatch, Drop in DC voltage. Construction Failure : Deformation in the switch blades, The levelling of track mismatch, Bad sitting of switch blades to the base                                        plate, Stock rail misalignment, Fastening bolt or screw on the track element was loose. Mechanical Failure   : Driving rod misalignment, Detection rod misalignment, Fastening bolt or screw on the switch machine                                              element was loose, Installation of strecher bar/back drive (if any) too wide. The main purpose of Go and No Go test is to keep safe condition of turnout while the switch blade at area between switch toe up to driving rod position has a gap. Obstruction Go test for simulate there is has a gap that the trains are allow to passing the turnout. Obstruction No Go test for simulate there is has a gap that the trains are not allow to passing the turnout. Lets analyse parameter of Switches and Wheelset to convincing that Go an No Go test are required. Please see figure 13_Secant contact, refer to document CENELEC DIN EN 13232-9:2012-01 Railway Applications – Track – Switches and Crossing Part 9 : Layout page number  20.   In figure 13 was explained that contact point of stock rail and switch rail shall be not contact with the dangerous zone of  the wheel. To comply this requirement therefore, Go and No Go test are required to be performed for installation and maintenance during train operation. Please see the dangerous zone of the wheel on figure1 – Key wheel dimensions (in addition to profile details), refer to document CENELEC DIN EN 13232-3:2012-01 Railway Applications – Track – Switches and Crossing Part 3 : Requirements for wheel/rail interaction  page number  6.   Obstruction Go test . Purpose of Obstruction Go test to ensure with maximum value the trains are allow to passing the turnout while switch blade get obstacle or deformation which create gap. The test itself using shim with thickness 1.5 mm up to 3 mm (but depend on regulation each country or project). The location of obstacle/shim to carrying the test is from the switch toe up to 20 cm from switch toe. The location shall be there because  the switch toe is the critical zone while the train moving toward set of switch machine. Therefore, with the value of obstruction Go test has  allowed the train passing the turnout. With consideration that contact dangerous zone on wheelset doesn’t has contact with switch blade ( please see figure 14_Safe secant contact, refer to document CENELEC DIN EN 13232-9:2012-01 Railway Applications – Track – Switches and Crossing Part 9 : Layout page number  21). The test procedure itself is put shim with the specific value for Obstruction Go test on the opening switch blade. Throw the switch machine until to the final position. If switch machine was locked and get detection of position, it mean the test is pass.   Obstruction No Go test. Purpose of obstruction No Go test to ensure with minimum value the trains are not allow passing the turnout while switch blade get obstacle or deformation which create  gap. The test itself using shim with thickness 2 mm up to 5 mm (but depend on regulation each country and project). The location of obstacle/shim to carrying the test is from the switch toe up to 20 cm from switch toe. The location shall be there because  the switch toe is the critical zone while the train moving toward set of switch machine. This test will declared pass, while the closed switch blade  has an obstacle No Go  then the end of movement was not in the final position. The meaning if in the final position is refer to a book Railway Signalling  Edited by O.S. Nock , First Published 1980 ©1980 Institution of  Railway  Signal Engineer, on Page 98 with sub-title  “The sequence of operations in power working is therefore”letter (c) The points are locked in their new position, the last movement  of  the locking plunger completing the detection circuit in the new position. Base on the article above, it could be concluded that the final position of switch machine movement is switch blade was locked in the new position and then the detection circuit get in the new position. Therefore, while closed switch blade has an Obstruction No Go then it will be not locked and no detection. The main purpose this test is to avoid derailment while the gap of closed switch blade too big. Therefore, with obstruction No Go test could  identify that turnout unsafe condition. Because the position of closed switch blade doesn’t in the final position. To make a clear why if the closed switch blade is unsafe condition please see figure 15_Dangerous secant contact, refer to document CENELEC DIN EN 13232-9:2012-01, Railway Applications – Track – Switches and Crossing Part 9 : Layout page number  22 . In figure 15 explained that if the gap too wide, the contact dangerous zone of wheelset will contact with switch blade. With this condition has possibility the wheelset will climbed out the switch blade. But the value of obstruction No Go has been confirmed by manufacture that the value still on minimum risk. The author's purpose in this article is to deep search about the topic above. If the readers has another reference regarding the topic or any critics or any suggestion please feel free to comment to this article. Because this opening discussion for everyone. ======================================================================================================= Author : Andree Litaay Reference : CENELEC DIN EN 13232-9:2012-01, Railway Applications – Track – Switches and Crossing Part 9 : Layout CENELEC DIN EN 13232-3:2012-01 Railway Applications – Track – Switches and Crossing Part 3 : Requirements for wheel/rail interaction Railway Signaling Edited by O.S. Nock , First Published 1980 ©1980 Institution of  Railway  Signal Engineer

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Deepu Dharmarajan -
Posted 3 years ago

SRA (TfNSW) SIGNALLING & ELECTRICAL SYMBOLS

Signalling

CONTENTS   The following pages show the signalling and schematic symbols used by the State Rail Authority of New South Wales on their plans and drawings. They are provided for reference use throughout the course. They are reproduced from SRA (Currently TfNSW) training material.   TRACK PLAN AND WORKING SKETCH SYMBOLS MECHANICAL SIGNALS POWER WORKED SIGNALS SINGLE LIGHT INDICATION WAYSIDE BUILDING AND STRUCTURES TRACK CIRCUIT DEVICES INTERLOCKING SYMBOLS APPARATUS HOUSINGS RELAYS AND CONTACTS CONTACTS OPERATED BY SIGNALS LOWER QUADRANT SEMAPHORE SIGNALS, INCLUDING BANNER SIGNALS CONTACTS OPERATED BY POINTS LEVER CONTACTS CATCH ROD CONTACTS MISCELLANEOUS APPARATUS 

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