Elevating Grader
Прочитайте и письменно переведите текст.
Excavator
Прочитайте текст. Расскажите по-английски его основное содержание.
Постройте предложения, соединяя по смыслу указанные ниже части предложений.
| 1. A series of tests of the new grader … 2. The scraper can get to work … 3. When operating a motor grader … 4. The capacity of a motor-grader … 5. The performance of self-operating graders … 6. The mechanic examined the device in all its details… 7. The tractor has a wide track and good towability … | 1. … the following ought to be taken into account. 2. … had to be carried out last week. 3. … after the bulldozer. 4. … may be classified as excellent. 5. … should be expressed in cubic yards. 6. … designed to be easily towed. 7. … wishing to find out the cause of the trouble. |
Mechanical excavators or navies are now recognized as an essential part of the larger builder’s equipment for use upon the construction of large buildings and housing estates. Building operations, of course, embody varying classes of work, and while the economy and efficiency of mechanical methods are well known, such economies would not result in many cases if it were necessary to apply a single-purpose machine separately to each of the various duties. The best application obviously is an all-purpose unit that can be converted to suit each class of work. Manufacturers of excavating machinery, in designing their machines, try to make one attachment serve as many purposes as possible, so that the changing of the type of equipment to suit the particular work in hand can be done without the expense of providing additional attachments; this has been achieved to a large extent in some of the smaller sizes of equipment.
This machine consists principally of a disc plough which turns a strip of earth on to a conveyor belt which may be 4 ft. wide and 18-24 ft. long. The belt, running at right angles to the travel of the plough, delivers the earth into lorries which must travel in the same direction and at the same speed as the grader. The ground must therefore be suitable, and sufficient space must be available.
Under favorable conditions these machines can dig and load 400 cu.yad. per hour at no greater cost than a stationary excavator. They are usually towed by caterpillar tractors and require a driver in addition to the driver of the tractor.
This type of machine is only suitable for very large quantities of excavation and in circumstances where sufficient transport is available to remove the excavation, or where the excavation can be dumped in a windrow and left. For hard chalk or other rock which the plough will not cut it is, of course, unsuitable and in wet sticky clay trouble is caused by clay sticking to the belt, etc.
Some graders are equipped with adjustable scarifying teeth ahead of the blade to loosen the earth prior to blading it.
Graders may have three to six forward gears, with speed varying from approximately 2 to 20 mph. The lower speeds are used for grader operations, while the higher speeds are used for travelling.
11. Сделайте сообщение по теме «Road Building Machinery».