I. Write down the words and word combinations below into your exercise book.
1. trap задерживать
2. inlet входное отверстие
3. suction всасывание
4. gear шестерня, зубчатая передача
5. screw червяк, винт, резьба
6. lobe лопасть
7. vane пластина насоса, лопатка, лопасть
8. clearance расстояние
9. spur зубчатое колесо
10. helical косозубый, винтовой, спиральный
11. herringbone шевронный, косозубый
12. project проектировать
13. gear pump шестеренный насос
14. rotary pump роторный насос
II. Explain what the following international words from text 4 mean:
Erosion, type, result, method, classification, classify, electric motor, element, center,
III Read and translate Text 4 with a dictionary:
TEXT 4
ROTARY PUMPS
All rotary pumps have rotating parts which trap the fluid at the inlet (suction) port and force it through the discharge port into the system. Gears, screws, lobes,, and vanes are commonly used to move the fluid. Rotary pumps are positive displacement of the fixed displacement type. Rotary pumps are designed with very small clearances between rotating parts and stationary parts to minimize slippage from the discharge side back to the suction side. They are designed to operate at relatively moderate speeds. Operating at high speeds causes erosion and excessive wear which results in increased clearances. There are numerous types of rotary pumps and various methods of classification. They may be classified by the shaft position – either vertically or horizontally mounted; the type of drive – electric motor, gasoline engine, and so forth; their manufacture’s name or their service application. However, classification of rotary pumps is generally made according to the type of rotating element.
GEAR PUMPS
Gear pumps are classified as either external or internal gear pumps. In external gear pumps the teeth of both gears project outward from their centers. External pumps may use spur gears, herringbone gears, or helical gears to move the fluid. In an internal gear pump, the teeth of one gear project outward, but the teeth of the other gear project inward toward the center of the pump. Internal gear pumps may be either centered or off-centered.
IV. Answer the following questions to the text:
1. How are rotary pumps designed?
2. How can rotary pumps be classified?
3. What can you say about gear pumps?
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