Almost every resident of the city at least once saw a passing tram or other similar electric vehicle on its streets. Similar vehicle options have been specifically designed to travel under such conditions. In fact, the design of the tram strongly resembles ordinary rail transport. However, their differences are precisely in fitness for different types of terrain.
Appearance story
The name itself is translated from English as a combination of a wagon (trolley) and a path. It is generally accepted that the tram is one of the oldest types of passenger public transport, which is still used in many countries around the world. The history of the appearance dates back to the 19th century. It is worth noting that the oldest tram operated on horse traction, and not on electricity. A more technologically advanced ancestor was invented and tested by Fyodor Pirotsky in St. Petersburg in 1880. After another year, the German company Siemens & Halske launched the first active tram service in a suburb of Berlin.
During the two world wars, this vehicle fell into decay, however, since the 1970s, its popularity has increased significantly again. The reasons for this were environmental considerations and new technologies. At the heart of the tram lay electric traction on the air contact network. Subsequently, new ways were created to bring the car into motion.
Tram evolution
All types are united by the fact that they work on electricity. The exception is only the less popular cable (cable) and diesel trams. Equestrian, pneumatic, petrol, and steam varieties were also created and tested earlier. Traditional electric trams operate either on the air contact network, or powered by batteries or a contact rail.
The evolution of this type of transport led to its division into types according to their purpose, including passenger, freight, office and special. The latter type includes many subtypes such as a mobile power plant, a technical fly, a crane car and a compressor car. For passengers, the design of the tram also depends on the system on which it travels. She, in turn, can be urban, suburban or intercity. In addition, the systems are divided into conventional and high-speed, which may include underground tunneling options.
Tram power supply
At the dawn of development, each infrastructure service company connected its own power plant. The fact is that the networks of those times did not yet have sufficient power, and therefore had to do it by their own means. All trams are powered by direct current with a relatively low voltage. For this reason, transferring a charge over long distances is very inefficient from a financial point of view. To improve the network infrastructure, traction substations began to be installed near the lines, converting alternating current to direct current.
To date, the nominal output voltage has been set at 600 V. The rolling stock of the tram at the current collector receives 550 V. In other countries, sometimes increased voltage values are applied - 825 or 750 V. The last of the values is the most relevant in European countries at the moment. As a rule, tram networks have a common energy economy with trolley buses, if any, in the city.
Traction Motor Description
It is this type that is used most often. Previously, only direct current received from substations was used for powering. However, modern electronics made it possible to create special converters inside the design. Thus, when answering the question of which engine the tram has in its modern version, one should also mention the possibility of using an engine based on alternating current. The latter are better for the reason that they practically do not require any repairs or regular maintenance. This applies, of course, only to AC induction motors.
Also, the design also includes another important component - the control system. Another common name sounds like a device for regulating current through a TED. The most popular and easiest option to perform is considered to be control by means of powerful resistances connected in series to the engine. Of the varieties, NSI, indirect non-automatic RKSU or indirect automatic RKSU systems are used. There are also separate types like TISU or transistor CS.
The number of wheels on the tram
Extremely common today, low-floor variations of this vehicle. Design features make it impossible to make an independent suspension for each wheel, which is why it is necessary to install special wheelsets. Alternative solutions to this problem are also applied. The number of wheels depends on the particular embodiment of the tram structure and, to a greater extent, on the number of sections.
In addition, the layout is different. Most multi-section trams are equipped with driven wheelsets (which have a motor) and non-driven. To increase agility, usually increase the number of compartments. If you are interested in how many wheels a tram has, you can find the following information:
- One section. Two or four drive or two drive and one non-drive pair of wheels.
- Two sections. Four drive and two non-drive or eight drive pairs of wheels.
- Three sections. Four drive and non-drive pairs of wheels in different combinations.
- Five sections. Six drive pairs of wheels. Two pieces go through one section starting from the first.
Features of driving a tram
It is considered relatively simple, because transport moves strictly on rails. This means that as such manual control is not required from the tram driver. At the same time, the car driver should be able to correctly use traction and braking, which is achieved by timely switching of the reverse and forward gears.
The rest of the tram obeys the uniform rules of the road at a time when it follows the city streets. In most cases, this transport takes precedence over cars and other means of transportation that are not dependent on the rail. The tram driver must necessarily obtain the right to drive the appropriate category and pass a theoretical test for knowledge of traffic rules.
General arrangement and design
The body of modern representatives is usually made of solid metal, and as separate elements it has a frame, frame, doors, floor, roof, as well as internal and external cladding. As a rule, the shape narrows towards the ends, due to which the tram easily overcomes curves. The elements are connected by welding, riveting, using screws and glue.
In the old days, wood was also widely used, which served as both an element of the frame and material for decoration. In the device of the tram at the moment, preference is given to plastic elements. Also, the design includes turn signals, brake lights and other means for indicating to other participants in the movement.
Coordination and speed indicators
In the same way as in the case of trains, this transport has its own service for tracking the performance of traffic and the correctness of routes. Dispatchers are engaged in the operational adjustment of the schedule if any unforeseen situation on the line has occurred. This service is also responsible for issuing backup trams or buses for replacement routes.
Traffic rules in urban areas may vary from country to country. For example, in Russia, the estimated speed of the tram is in the range from 45 to 70 km / h, and for systems with an operating speed of 75 to 120 km / h, building codes prescribe the prefix “high-speed”.
Pneumatic equipment
Wagons in their modern design are often equipped with special compressors, which are based on pistons. Compressed air is very useful for several regularly performed operations, including the actuation of door drives, brake systems and other auxiliary mechanisms.
Moreover, the presence of pneumatic equipment is not required. Due to the fact that the tram device assumes a constant supply of current, these structural elements can be replaced by electric ones. This significantly simplifies the maintenance of systems, but to some extent the total cost of production of one wagon rises.