Because safety is of high importance when train cars move across the rails, there must be inspections. The cars are heavy and have moving parts that can break or become defective. Worn or broken parts can drag, pound, and generally destroy the cars and the track structure they run on. Parts and loads must not extend outside the limits of the car, and there should be no leaking of the cars' contents.
Quality inspections are needed not just before a train is moved, but also as it travels to its destination.
Overview
A hot bearing detector w/ dragging equipment unit
There are several levels of inspection on railroad equipment. Inspections are continuous, starting when the car is being built and repeated at regular intervals.
Before the train begins its journey, the locomotives and the cars are checked. This is done by mechanical department workers, sometimes cameras and scanners are also used. Some of the items certified good to go are things like the braking system including hand-brake release, brake application, condition of the air valves, piping and hoses, communication equipment, and many more. Very much like the checklist an airline might use. When the pretrip work is done, the train is considered safe to move.
Once the movement begins, the train is continuously watched by employees, scanners and monitors. These are sometimes called "in motion defect detectors" or defect detectors (DD).
Technologies
As the railroad has evolved from block stations and control towers to a centralized dispatching system, they have also moved to more advanced inspection tools. The technologies in use today vary from a simplistic paddle and switch to infrared thermography, laser scanning, and even ultrasonic audio analysis. These devices are used to inspect engines, cars and the loads on them.[1]
The systems used on North American and other railways fall into a dozen or so major groups, some are listed below.
Wheel impact load detector (WILD)
Sensors for a railway wheel impact load monitor, Lara, Victoria, Australia
High impact wheels have some defect where it does not roll smoothly along the track.[2][3] A flaw in a wheel causes vibrations or banging. This is very destructive to the track structure and the rolling stock.
Checks for overloads or shifted loads that can be dangerous.[3]
Truck hunting
Truck hunting
Looks for hunting oscillation of the trucks or wheelset; a lateral movement in the gauge of the track, like drifting back and forth in a lane of traffic. This action can increase above a certain speed to the point the wheel flanges impact the rails, potentially causing damage to both. There is also force absorbed by this action that will affect the energy consumption of train operations.
Truck performance
Truck hunting and performance detector—TBOGI system
Is stiff or poorly steering or axle sets that don't follow the path of the track correctly. Presents itself like 'dog tracking" where the trucks are biased to run against the flange on one side or the other. Truck performance defects include tracking position and angle of attack on a per-axle basis, as well as rotation, shift, inter-axle misalignment, and tracking error on a per-bogie basis. Truck performance detectors can provide early detection of bogie defects, and early warning of derailment risks through flange climb or rail break.[4]
Acoustic bearing detectors
Listens with special microphones for internal bearing defects as the equipment moves across the detector.[5][6] These are very sensitive and can detect problems before the bearing fails.
High wheel temperature detectors
Hot box and hot wheel detection system, PHOENIX MB (SST Signal & System Technik GmbH)
Look for hot wheels, which are generally caused by braking equipment failures. This equipment may be combined with bearing temperature detectors (below).[7]
Bearing temperature scanners ("hot box" detectors)
This type of defect detector uses ultra sensitive infrared cameras called pyrometers. These devices take the temperature of each bearing as it passes by the scanner.[7] This data is then compared to preset "Alarm limits". If the whole consist is without problems, the train is passed. If however there is overheating in one or more of the bearings (a hot box), an alarm is given.
These messages can be by radio to the train crew or might be sent to the dispatch center for handling. The data is also used to detect a trend over several locations that might predict a future failure. If an alarm is sent, the train is stopped, and either the defect is corrected or the offending car is removed for repair. Many derailments are avoided by these devices which is why thousands of them are in use on rail systems across the world.
Dragging equipment detectors
As the name suggests, they are able to detect things hanging or dragging under the cars. These consist of a series of plates mounted on a pivot shaft. An object hanging or dragging will contact the plates, moving them and breaking a circuit. This will trigger an alarm and alert the crew. Many are stand-alone detectors, but most often are integrated into bearing temperature scanning locations.
These are able to measure the height and width of rolling stock, so that cars and loads which won't fit under bridges or through tunnels are stopped. Most often they are optical line of sight devices that trigger an alarm when the beam is broken. They are often seen at a bearing temperature scanning locations, they then report out as part of the detectors regular train inspection report. Mounted on poles or a bridge structure, the optical line is adjusted for a set height and width, it can then send an alarm when something too big to fit the clearance limits ahead passes its view.
Derailment detector
Is a simple "broken wire" type device that notifies the train crew they are off the track somewhere in their train.
Pantograph inspection
An automated scanner inspects the pantograph of a passing train.
A system which monitors the integrity of the pantograph.[8] These are normally based on a vision system which takes pictures of the pantographs and performs an analysis based on computer vision algorithms. A pantograph uses a carbon strip to conduct electricity between the catenary and the pantograph. When these are damaged or worn out, the pantograph can tear down the catenary causing train delays.
Laser and optical scanning wayside inspection devices (known as TBOGI—Truck Bogie Optical Geometry Inspection Systems) make images of the flange and tread. These measurements are compared with acceptable dimensions. When worn beyond limits, the wheels are scheduled for replacement. If beyond a safe level the axle set is removed from service.
Trend monitoring systems
These back office systems are predictive, finding equipment problems as they start to develop.[6]
A bogie is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transport. A bogie may remain normally attached or be quickly detachable ; it may contain a suspension within it, or be solid and in turn be suspended ; it may be mounted on a swivel, as traditionally on a railway carriage or locomotive, additionally jointed and sprung, or held in place by other means.
An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside a central hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type of axle is referred to as a spindle.
Rail transport terms are a form of technical terminology applied to railways. Although many terms are uniform across different nations and companies, they are by no means universal, with differences often originating from parallel development of rail transport systems in different parts of the world, and in the national origins of the engineers and managers who built the inaugural rail infrastructure. An example is the term railroad, used in North America, and railway, generally used in English-speaking countries outside North America and by the International Union of Railways. In English-speaking countries outside the United Kingdom, a mixture of US and UK terms may exist.
In rail transport, a derailment occurs when a rail vehicle such as a train comes off its rails. Although many derailments are minor, all result in temporary disruption of the proper operation of the railway system and they are a potentially serious hazard.
A wheel speed sensor (WSS) or vehicle speed sensor (VSS) is a type of tachometer. It is a sender device used for reading the speed of a vehicle's wheel rotation. It usually consists of a toothed ring and pickup.
A defect detector is a device used on railroads to detect axle and signal problems in passing trains. The detectors are normally integrated into the tracks and often include sensors to detect several different kinds of problems that could occur. Defect detectors were one of the inventions which enabled American railroads to eliminate the caboose at the rear of the train, as well as various station agents placed along active routes to detect unsafe conditions. The use of defect detectors has since spread overseas to other railroad systems.
A hot box is the term used when an axle bearing overheats on a piece of railway rolling stock. The term is derived from the journal-bearing trucks used before the mid-20th century. The axle bearings were housed in a box that used oil-soaked rags or cotton to reduce the friction of the axle against the truck frame. When the oil leaked or dried out, the bearings overheated, often starting a fire that could destroy the entire railroad car if not detected early enough.
The DB Class 101 is a class of three-phase electric locomotives built by Adtranz and operated by DB Fernverkehr in Germany. 145 locomotives were built between 1996 and 1999 to replace the 30-year-old and aging Class 103 as the flagship of the Deutsche Bahn, primarily hauling Intercity services. This class encompasses the latest generation of locomotives of the Deutsche Bahn.
A dolly is an unpowered vehicle designed for connection to a tractor unit, truck or prime mover vehicle with strong traction power.
An axle counter is a system used in railway signalling to detect the clear or occupied status of a section of track between two points. The system generally consists of a wheel sensor and an evaluation unit for counting the axles of the train both into and out of the section. They are often used to replace a track circuit.
Rail inspection is the practice of examining rail tracks for flaws that could lead to catastrophic failures. According to the United States Federal Railroad Administration Office of Safety Analysis, track defects are the second leading cause of accidents on railways in the United States. The leading cause of railway accidents is attributed to human error. The contribution of poor management decisions to rail accidents caused by infrequent or inadequate rail inspection is significant but not reported by the FRA, only the NTSB. Every year, North American railroads spend millions of dollars to inspect the rails for internal and external flaws. Nondestructive testing (NDT) methods are used as preventive measures against track failures and possible derailment.
ER2 electric trainset is a DC electric multiple unit which was in production by the Railroad Machinery Plants of Riga from June 1962 to mid-1984. It was essentially an improvement of the ER1 design, featuring footboards for low platforms, and aprons for high platforms, as well as improved electrical equipment and minor changes to the bodywork. Since the mid-1960s, the ER2 has been the most widely used type of suburban train in the Soviet Union and its successor states.
A wheelset is a pair of railroad vehicle wheels mounted rigidly on an axle such that both wheels rotate in unison. Wheelsets are often mounted in a bogie – a pivoted frame assembly holding at least two wheelsets – at each end of the vehicle. Most modern freight cars and passenger cars have bogies each with two wheelsets, but three wheelsets are used in bogies of freight cars that carry heavy loads, and three-wheelset bogies are under some passenger cars. Four-wheeled goods wagons that were once near-universal in Europe and Great Britain and their colonies have only two wheelsets; in recent decades such vehicles have become less common as trainloads have become heavier.
A train wheel or rail wheel is a type of wheel specially designed for use on railway tracks. The wheel acts as a rolling component, typically press fitted onto an axle and mounted directly on a railway carriage or locomotive, or indirectly on a bogie, also called a truck. The powered wheels under the locomotive are called driving wheels. Wheels are initially cast or forged and then heat-treated to have a specific hardness. New wheels are machined using a lathe to a standardized shape, called a profile, before being installed onto an axle. All wheel profiles are regularly checked to ensure proper interaction between the wheel and the rail. Incorrectly profiled wheels and worn wheels can increase rolling resistance, reduce energy efficiency and may even cause a derailment. The International Union of Railways has defined a standard wheel diameter of 920 mm (36 in), although smaller sizes are used in some rapid transit railway systems and on ro-ro carriages.
The Transnet Freight Rail Class 20E of 2013 is a South African electric locomotive.
An equalising beam, equalising lever or equalising bar links the suspension of two or more adjacent axles of a vehicle, especially a railway locomotive.
The Transnet Freight Rail Class 21E of 2014 is a South African electric locomotive.
1 2 Czichos, Horst (2013). Handbook of technical diagnostics: fundamentals and application to structures and systems. Berlin: Springer. p.531. ISBN9783642258503.
↑ Anderson, David; Gautier, Pierre-Etienne; Iida, Masanobu; Nelson, James T.; Thompson, David; Tielkes, Thorsten; Towers, David A.; De Vos, Paul; Nielsen, Jens C. O. (2015). Noise and Vibration Mitigation for Rail Transportation Systems: Proceedings of the 11th International Workshop on Railway Noise, Uddevalla, Sweden, 9?13 September 2013. Berlin, Heidelberg: Springer Berlin Heidelberg Imprint Springer. p.256. ISBN9783662448328.
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