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Dynamic Envelope
A loading gauge is a diagram or physical structure that defines the maximum height and width dimensions in railway vehicles and their loads. Their purpose is to ensure that rail vehicles can pass safely through tunnels and under bridges, and keep clear of platforms, trackside buildings and structures. Classification systems vary between different countries, and gauges may vary across a network, even if the track gauge is uniform. The term loading gauge can also be applied to the maximum size of road vehicles in relation to tunnels, overpasses and bridges, and doors into automobile repair shops, bus garages, filling stations, residential garages, multi-storey car parks and warehouses. A related but separate gauge is the structure gauge, which sets limits to the extent that bridges, tunnels and other infrastructure can encroach on rail vehicles. The difference between these two gauges is called the clearance. The specified amount of clearance makes allowance for wobbling of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Why London Underground Is Nicknamed The Tube
Why may refer to: * Causality, a consequential relationship between two events * Reason (argument), a premise in support of an argument, for what reason or purpose * Grounding (metaphysics), a topic in metaphysics regarding how things exist in virtue of more fundamental things. * Why?, one of the Five Ws used in journalism Music Artists * Why? (American band), a hip hop/indie rock band formed in Oakland, California, in 2004 ** Yoni Wolf, formerly known by the stage name Why? * Why (Canadian band), a rock band formed in Winnipeg, Manitoba, in 1993 * Why?, a 1990s UK folk band, two members of which formed Quench in 2001 Albums * ''Why'' (Baby V.O.X album) or the title song, 2000 * ''Why?'' (Ginger Baker album) or the title song, 2014 * ''Why'' (Prudence Liew album) or the title song, 1987 * ''Why?'' (They Might Be Giants album), 2015 * ''Why?'', by Jacob Whitesides, 2016 * ''Why'', by Moahni Moahna, 1996 * ''Why?'', by the MonaLisa Twins, 2022 EPs * ''Why'' (Discharge EP) o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Envelope (motion)
{{other uses, Envelope (other) In mechanical engineering, an envelope is a solid representing all positions which may be occupied by an object during its normal range of motion. Another (jargon) word for this is a "flop". Wheel envelope In automobile design, a wheel envelope may be used to model all positions a wheel and tire combo may be expected to occupy during driving. This will take into account the maximum jounce and rebound allowed by the suspension system and the maximum turn and tilt allowed by the steering mechanism. Minimum and maximum tire inflation pressures and wear conditions may also be considered when generating the envelope. This envelope is then compared with the wheel housing and other components in the area to perform an interference/collision analysis. The results of this analysis tell the engineers whether that wheel/tire combo will strike the housing and components under normal driving conditions. If so, either a redesign is in order, or that wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schnabel Car
A Schnabel car or Schnabel wagon is a specialized type of railroad freight car. It is designed to carry heavy and oversized loads in such a way that the load makes up part of the car. The load is suspended between the two ends of the cars by lifting arms; the lifting arms are connected to an assembly of span bolsters that distribute the weight of the load and the lifting arm over many wheels. When a Schnabel car is empty, the two lifting arms are connected to one another and the car can usually operate at normal freight train speeds. Some Schnabel cars include hydraulic equipment that will either lift or horizontally shift the load while in transit (at very low speeds) to clear obstructions along the car's route. As of 2012, there were 31 Schnabel cars operating in Europe, 30 in North America, 25 in Asia, and one in Australia. Gallery Image:Tragschnabelwagen mit Transformator (8789).jpg, ÖBB Schnabel car with an electrical transformer near Koblenz in May 2009 Image:JRF Shiki8 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rapid Transit
Rapid transit or mass rapid transit (MRT), also known as heavy rail or metro, is a type of high-capacity public transport generally found in urban areas. A rapid transit system that primarily or traditionally runs below the surface may be called a subway, tube, or underground. Unlike buses or trams, rapid transit systems are railways (usually electric railway, electric) that operate on an exclusive right-of-way (transportation), right-of-way, which cannot be accessed by pedestrians or other vehicles, and which is often grade-separated in tunnels or on elevated railways. Modern services on rapid transit systems are provided on designated lines between rapid transit station, stations typically using electric multiple units on rail tracks, although some systems use guided rubber tires, magnetic levitation (''maglev''), or monorail. The stations typically have high platforms, without steps inside the trains, requiring custom-made trains in order to minimize gaps between train a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platform Gap
A platform gap (also known technically as the platform train interface or PTI in some countries) is the space between a train car (or other mass transit vehicle) and the edge of the station platform, often created by geometric constraints, historic legacies, or use of partially compatible equipment. Many high-quality bus rapid transit (BRT) systems also use high platforms at station stops to allow fast and efficient level boarding and alighting, but potentially leaving hazardous gaps between the platforms and the buses. Alignment setups such as Kassel curbs help to reduce platform gaps without requiring time-consuming manual alignment at each BRT station stop. Straight platforms The ideal platform would be straight and align perfectly with a train or other large vehicle. Even in this case, a small gap between the conveyances and the platform is necessary to allow the vehicles to move freely without rubbing against the platform edge. In 2007, the Long Island Rail Road regarded a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwell Time (transportation)
In transportation, dwell time or terminal dwell time refers to the time a vehicle such as a public transit bus or train spends at a scheduled stop without moving. Typically, this time is spent boarding or deboarding passengers, but it may also be spent waiting for traffic ahead to clear, trying to merge into parallel traffic, or idling time in order to get back on schedule. Dwell time is one common measure of efficiency in public transport, with shorter dwell times being universally desirable. Rail systems Dwell times are particularly important for a rail system. Rail headways increase where the dwell times are high. Dwell times are an important focus for rail systems; a reduction in a dwell time can often result in a reduced headway. Passengers who want to board and alight from a train need time to do so. Almost always passengers disembark first, and then passengers waiting on a platform board. A variety of different factors determine how long this takes, including the size of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Railway Platform Height
Railway platform height is the built height – ''above top of rail (ATR)'' – of passenger platforms at stations. A connected term is ''train floor height'', which refers to the ATR height of the floor of rail vehicles. Worldwide, there are many, frequently incompatible, standards for platform heights and train floor heights. Where raised platforms are in use, train widths must also be compatible, in order to avoid both large gaps between platform and trains and mechanical interference liable to cause equipment damage. Differences in platform height (and platform gap) can pose a risk for passenger safety. Differences between platform height and train floor height may also make boarding much more difficult, or impossible, for wheelchair-using passengers and people with other mobility impairments, increasing station dwell time as platform or staff are required to deploy ramps to assist boarding. Platform ramps, steps, and platform gap fillers together with hazard warnings such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Envelope (motion)
{{other uses, Envelope (other) In mechanical engineering, an envelope is a solid representing all positions which may be occupied by an object during its normal range of motion. Another (jargon) word for this is a "flop". Wheel envelope In automobile design, a wheel envelope may be used to model all positions a wheel and tire combo may be expected to occupy during driving. This will take into account the maximum jounce and rebound allowed by the suspension system and the maximum turn and tilt allowed by the steering mechanism. Minimum and maximum tire inflation pressures and wear conditions may also be considered when generating the envelope. This envelope is then compared with the wheel housing and other components in the area to perform an interference/collision analysis. The results of this analysis tell the engineers whether that wheel/tire combo will strike the housing and components under normal driving conditions. If so, either a redesign is in order, or that wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering Tolerance
Engineering tolerance is the permissible limit or limits of variation in: # a physical dimension; # a measured value or physical property of a material, manufactured object, system, or service; # other measured values (such as temperature, humidity, etc.); # in engineering and safety, a physical distance or space (tolerance), as in a truck (lorry), train or boat under a bridge as well as a train in a tunnel (see structure gauge and loading gauge); # in mechanical engineering, the space between a bolt and a nut or a hole, etc. Dimensions, properties, or conditions may have some variation without significantly affecting functioning of systems, machines, structures, etc. A variation beyond the tolerance (for example, a temperature that is too hot or too cold) is said to be noncompliant, rejected, or exceeding the tolerance. Considerations when setting tolerances A primary concern is to determine how wide the tolerances may be without affecting other factors or the outcome of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light which is ''coherent''. Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers and lidar (light detection and ranging). Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum. Alternatively, temporal coherence can be used to produce ultrashort pulses of ligh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clearance Car
A clearance car is a type of railroad car in maintenance of way service. Its purpose is to check the clearances around the tracks and ensure that trains conforming to the railroad's standard loading gauge or ''dynamic envelope'' will not encounter any obstruction. Additionally, by measuring the actual clearances along a route, the railroad can determine whether outsize loads can be accommodated along that route, and the largest size feasible. Design Early clearance cars simply consisted of an outline of the system loading gauge attached to a railroad car, which would be towed along the route to ensure the clearances were still sufficient. Later clearance cars functioned by using physical feelers—rods which extended from the car in all directions which would be deflected back by obstructions. These would be connected to instrumentation which displayed the actual clearance at that point. These feelers have an advantage in that they bounce back and do not break if they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Eye
An electric eye is a photodetector used for detecting obstruction of a light beam. An example is the door safety system used on garage door openers that use a light transmitter and receiver at the bottom of the door to prevent closing if there is any obstruction in the way that breaks the light beam. The device does not provide an image; only presence of light is detectable. Visible light may be used, but infrared radiation conceals the operation of the device and typically is used in modern systems. Originally, systems used lamps powered by direct current or the power line alternating current frequency, but modern photodetector systems use an infrared light-emitting diode modulated at a few kilohertz, which allows the detector to reject stray light and improves the range, sensitivity and security of the device. Examples Highway vehicle counter * In the 1930s, an electric eye vehicle counter was introduced in the US using two IR lamps set apart so that only cars and not pedestria ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
