Максимальные динамическая и статическая нагрузка (радиальная и осевая).

Максимальная скорость (оборотов в минуту для радиальных подшипников).

Посадочные размеры.

Класс точности подшипников.

Требования к смазке.

Ресурс подшипника до появления признаков усталости, в оборотах.

Шумы подшипника

Контрольная работа № 13

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The small car gets (go) from 12 batteries under the hood. Rather than conventional lead-acid batteries the car uses batteries made of nickel and iron.

Due to their chemical composition they deliver double the electrical output of ordinary car batteries and have a life span twice as long.

You can judge for yourself, the car achieves a top speed of 62 miles per hour and cruises for 124 miles before needing a recharge.

It takes from 8 to 10 hours to recharge using a built-in recharger that can plug into any standard outlet.

It's a 17,5 kilowatt motor driving the front wheels. Like all electric vehicles the car runs almost silently and is virtually nonpolluting.

 II. Translate the text.

Инжекторный двигатель существенно улучшает эксплуатационные и мощностные показатели автомобиля (динамика разгона, экологические характеристики, расход топлива). Инжекторные двигатели, безусловно, гораздо совершеннее карбюраторных. Отечественные инжекторные двигатели хорошо адаптированы к нашему холодному климату, поэтому неплохо заводятся при очень низкой температуре.

   

Контрольная работа № 14

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  The lathe is one of the most useful and versatile machines in industry, and is capable of carrying out many machining oper­ations. The main components of the lathe are the headstock and tailstock at opposite ends of a bed, and a toolholder between them which holds the cutting tool. The toolholder stands on a cross slide which enables it to move across the saddle or carriage as well as along it, depending on the kind of job it is doing. The ordinary centre lathe can accommodate only one tool at a time on the tool-holder, but a turret lathe is capable of holding five or more tools on the revolving turret. The lathe bed must be very solid to avoid vibrations

    The headstock incorporates the driving gear and a spindle which holds the workpiece and causes it to rotate. The cutting speed of the tool is an important factor. Tapered centres in the hollow nose of the spindle and of the tailstock hold the work firmly between them. A feed shaft from the headstock drives the toolholder along the saddle, either forwards or backwards, at a fixed and uniform speed! This enables the operator to make accurate cuts and to give the work a good finish. Gears between the spindle and the feed shaft control the speed of rotation of the shaft, and the forward or back­ward movement of the toolholder. The gear which the operator will select depends on the type of metal which he is cutting and the amount of metal he has to cut off. For a deep or roughing cut the forward movement of the tool should be less than for a finishing cut.

  Centres are not suitable for every job on the lathe. The operator can replace them by various types of chucks, which hold the work between jaws, depending on the shape of the work and the particu­lar cutting operation. He will use a chuck, for example, to hold a short piece of work, or work for drilling, boring or screw-cutting. A transverse movement of the tool post across the saddle enables the tool to cut across the face of the workpiece and give it a flat surface. For screw-cutting, the operator engages the lead screw, a long screwed shaft which runs along in front of the bed and which rotates with the spindle. The lead screw drives the toolholder for­wards along the carriage at the correct speed, and this ensures that the threads on the screw are of exactly the right pitch. The operator can select different gear speeds, or reverse the movement of the carriage and so bring the tool back to its original position.

Lathes are now made with numerical control (for short NC) and with computer control. They work automatically according to pro­teins. The unit is called a machining centre.

  

Контрольная работа №15

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The two-cycle principle

The suction and exhaust strokes can be eliminated if, at the end of the power stroke, the two valves are opened simultaneously and the fresh charge is forcibly blown in through the inlet valve driving out the waste gases through the exhaust valve. Then the two valves are closed again and the charge is ready for compression.

A simpler way of doing the same thing is to provide openings in the cylinder wall at the lower end in such a way that they are uncovered by the piston as it nears the end of the power stroke. Valves are then no longer necessary.

Since the cycle can now be completed in two strokes, it is called two-stroke or two-cycle. A two-cycle has a working stroke at every crankshaft revolution, and, therefore, gives nearly twice the power of a four-cycle engine, which has a working stroke only at every other crankshaft revolution.

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