Category: Automakers

Category D

2023
Video: Category D
Video: International accordion competition VILNIUS 2021, Pankiv Ihor , category "D" 2023, February
Category D
Category D
Anonim

Any bus, as a rule, is the fruit of the labor of not one company, but a certain consortium. Of course, the designers and designers of the brand holder create new models, focusing on the technological capabilities of partners. But sometimes they demand almost impossible from them - otherwise cars of all brands would be similar to each other and at the same time to a large aquarium with wheels. The competition is tough, one supplier can’t cope - there will quickly be another, and then it will yield in price.

Motor builders create bus versions of engines. For the sake of compactness, they try to get by with a smaller working volume, without losing power. Laying an in-line diesel to one side is a well-known trick, and if Volvo on its D12 and MAN on the newest D20 with Common Rail only change the lubrication systems a little, then IVECO makes a dry sump.

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[caption id = "attachment_188683" align = "aligncenter" caption = "Above the design of" NEO MAN Starliner ", recognized by the bus of 2006, it seems that glassblowers have worked the most.

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The location and number of cylinders are dictated by the main (that is, freight) production program, because buses are produced several times less. Scania is adapting a new 310-horsepower 9-liter “five” with two balancer shafts to the city’s Omni series, and on its large tourism projects, its Spanish partner IRIZAR - 12-liter “six” with a capacity of up to 420 hp And here is the Scania V-shaped motors with a volume of 16 liters and a capacity of up to 620 hp. until it was used in passenger transport. DAF, Renault and, of course, Cummins, Caterpillar and Deutsche are ready to make bus modifications of engines. The toxic standards of Euro III and Euro IV have overcome each in its own way: some with exhaust gas recirculation, some thanks to the turbocompound, diesel particulate filters and neutralizers. But in Euro V they fit according to a single recipe: injecting a urea solution into the catalyst installed in front of the muffler. In the West, the process is called SCR, and urea is called ADBlue.

However, Scania went its own way. The 9-liter “five” did without ADBlue, combining all the latest developments in it: electronically controlled pump nozzles, a particulate filter and exhaust gas recirculation. Some of them are returned to the engine cylinders, mixing with the supply air. And since the vacuum in the intake manifold of the diesel is small, a Venturi tube was built into it - it draws in exhaust gases. Of course, the “green motor” power dropped to 270 hp.

Another way to achieve minimal exhaust toxicity is to convert the diesel to gas. Replace pistons and heads, install spark plugs - return to the Otto cycle. Why is it so hard? Because Europeans have not made large gasoline engines for a long time. The leader of gasification is MAN, in which once - an irony of fate! - Rudolf Diesel himself worked. In Europe, more than 2, 500 MAN Lion's Sity buses are operated on methane. The Germans switched to gas 12-liter engines of the D2866 series. In diesel fuel they gave out more than 400 hp. at 1900 rpm, on natural gas, the speed increased to 2200, but the power still dropped to 245 hp.

However, a city bus is enough. Four aluminum-composite cylinders with a total volume of 1280 liters are placed on the roof. Methane under a pressure of 200 kgf / cm2 is enough for 400-500 kilometers.

By and large, there are three manufacturers of automatic boxes in the European market, three of them - ZF, Voith and Allison. The last two are famous for four- and five-speed gearboxes with GMF and built-in retarders. ZF makes mechanical with electro-pneumatic control and the number of gears from 6 to 16.

Gantry bridges with a gearbox shifted to the left for urban low-floor workers are made only by ZF and Raba, and, apparently, both will not remain without work. ZF also leads in the manufacture of independent front suspension for tourist liners and, of course, steering gears.

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However, not all small firms assemble buses "from the world on a thread" - on units of different manufacturers. Many people prefer complete chassis - with an engine, transmission, suspension and a ready-made driver's seat. It remains only to put your body on it - and the bus is ready. According to this scheme, GolAZ and Volzhanin work with the Scania chassis. The kits are made by MAN, VDL Bova, Van Hul, but they are not sold to anyone. The requirements for bodybuilders are quite strict - after all, there are their emblems on the bus.

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