Engine lubrication system

The purpose of lubrication is to reduce both friction and wear to the minimum. If moving parts are not separated by a film of lubricant the surface will rapidly wear away.

Friction is a force that reduces or stops motion of one surface over another. In many types of large diesels the pistons are provided with their own cooling system, the coolant being lubricating oil. The friction force depends on the nature of the surface and also on the kind of material. The rougher the surface and the softer the material, the greater the friction. The harder the material and the smoother the surface, the less the friction. The friction being great, the loss of power is greater. A great amount of friction is necessary in certain parts of the vehicle such as brakes, the clutch and other surfaces. It is impossible to eliminate the friction entirely.

The loss of power can be reduced to a minimum due to proper use of suitable lubricants.

The principal parts of the engine needing lubrication are the main crankshaft bearings, camshaft bearings, pistons and the cylinder walls.

Oil may be fed to a bearing in two ways. It may be delivered into an oil hole located above the bearing. From there it drains to the bearing surface. Or it may be fed directly to the bearing surface under pressure.

Notes:

lubricant – смазка, смазочное масло

film – тонкий слой

coolant – охлаждающая жидкость

piston – поршень

brake – тормоз

Exercise 13. Translate the text with a dictionary in written form:

Text С

A power shovel

A power shovel also known as a stripping shovel or a front shovel as well as an electric mining shovel is a bucket-equipped machine, usually electrically powered, used for digging and loading earth or fragmented rock and for mineral extraction.

Shovels normally consist of a revolving deck with a power plant, driving and controlling mechanisms, usually a counterweight, and a front attachment, such as a crane or boom which supports a handle also called a dipper or dipper stick with a digger or bucket at the end. Dipper is also sometimes used to refer to the handle and digger combined. The machinery is mounted on a base platform with tracks or wheels. Modern bucket capacities range from 8 cu m to nearly 80 cu m.

Power shovels are used principally for excavation and removal of overburden in open-cut mining operations, though it may include loading of minerals, such as coal. They are the modern equivalent of steam shovels, and operate in a similar fashion.

The shovel operates using several main motions: hoist – pulling the bucket up through the bank (i.e. the bank of material being dug); crowd – moving the dipper handle out or in to control the depth of cut and when positioning to dump; swing – rotating the shovel between digging and dumping; propel – moving the shovel unit to different locations or dig positions.

A shovel's work cycle, or digging cycle, consists of four phases: digging, swinging, dumping, and returning.

The digging phase consists of crowding the dipper into the bank, hoisting the dipper to fill it, then retracting the full dipper from the bank. The swinging phase occurs once the dipper is clear of the bank both vertically and horizontally. The operator controls the dipper through a planned swing path and dump height until it is suitably positioned over the haul unit (e.g. truck). Dumping involves opening the dipper door to dump the load, while maintaining the correct dump height. Returning is when the dipper swings back to the bank, and involves lowering the dipper into the tuck position to close the dipper door.

In the 1950s with the demand for coal at a peak many coal companies turned to the cheaper methods of strip mining, and excavator

manufacturers started offering a new super class of power shovels, commonly called giant stripping shovels. Most were built between the 1950s and the 1970s. The world's first giant stripping shovel for the coal fields was the Marion 5760. Larger models followed the successful 5760, culminating in the mid 60s with the gigantic 15,000 ton Marion 6360, nicknamed The Captain.

Unit 6

Grammar:

Gerund.

Exercise 1. Work out the following sounds:

[eI] pave, break, excavate, replace, frame

[qV] backhoe, loader, both, almost, tow

[Iq] rear, material, area, engineering

Exercise 2. Match the transcription to the words given below and define their meanings:

1. ['bAkIt]	1. check	1. универсальность
2. [vWsq'tIlItI]	2. allow	2. ковш
3. [q'semblI]	3. variation	3. оборудование
4. [sJt]	4. seat	4. заменять
5. [I'kwIpmqnt]	5. coupler	5. агрегат
6. [veqrI'eIS(q)n]	6.equipment	6. соединительное устройство
7. [tSek]	7. assembly	7. допускать
8. ['kAplq(r)]	8. replace	8. проверять
9. [q'laV]	9. bucket	9.разнообразие
10. [ri'pleIs]	10.versatility	10. сидение

Text A