Exercises. I. Use the following words and phrases in sentences of your own:

I. Use the following words and phrases in sentences of your own:

chuck, rotating vice, lathe spindle, independent jaw chuck, contracting chuck, chuck body, chuck key, to project, to reverse, motion, to transmit, to mesh, bevel gear, faceplate, mandrel

II. Answer the following questions:

1. Where are usually short parts held when being turned in a lathe? 2. What is a chuck? 3. V/hat types of chucks do you know'? 4. What purposes are chucks used for? 5. What kind of work are magnetic chucks adapted to? 6. How is the work held in a magnetic chuck? 7. How many faceplates are most lathes equipped with? 8. What kind of work is a mandrel used for? 9. What is. the advantage of mounting work on a mandrel?

III. Supply English equivalents for the following words and word combinations:

self-centering chuck, independent jaw chuck, collet chuck, radial slots, groove, spindle nose

IV Find in the text synonyms of the following words:

collet chuck, comfortably, with the help of, slot, to revolve

V. Give derivatives from the following words and translate them into Russian:

to divide, dependent, possible, cylinder, to open, to transmit, to ensure

VI. Read and translate the following text without using a dictionary and analyze the ing- forms and ed-forms:

The standard chucks generally furnished are mechanically operated by an automatic mechanism which gives the operator total freedom of both hands for handling the work. While the machine is running to cycle time¹ he simply places the work in the chuck which is held there by the work locator² then he releases the safety foot treadle³. There are no chucking levers or valves and gauges that require his attention and time. Standard chucks can be furnished with either two or three simple jaws and with the jaws contracting or expanding. Chucking pressures are the same at all positions and the pressures are adjustable for different types of work. All standard chucks are constructed entirely of steel having a solid steel body, and all the moving parts are made of hardened alloy steel to withstand wear.

¹. cycle time - цикл хронометрирования

². work locator - фиксатор

³. safety foot treadle – предохранительная ножная педаль

VII. Giving answers to the following questions describe the s independent four-jaw chuck shown in Fig. 28 and its a principle of operation:

1. What kind of chuck is shown in Fig. 28? 2. What group of chucks does the independent four-jaw chuck belong to? 3. How many jaws has the chuck? 4. Where are the four jaws of the chuck situated? 5. How can each jaw of the chuck be adjusted? 6. What possibility is offered by the independent adjustment of jaws? 7. What is the body of the chuck provided with?

VIII. Using the following words and word combinations describe the construction and principle of operation of the concentric chuck shown in Fig. 29:

a concentric chuck, to have three jaws, to move in and out, a chuck key, to be inserted, the opening, one of three bevel gears, to be meshed with a large bevel gear, on the flat reverse side, the large bevel gear, a multiturn spiral groove, to be cut, the motion of one of the bevel gears, to be transmitted, by means of the chuck, key, to move simultaneously and uniformly, the slots of the body, due to the spiral groove, rotating in that or another direction, the gear with the spiral grooves, to cause, approaching or removing, the jaws of the chuck, from the centre, due to this, the work, to be clamped or unclamped, the advantage, the concentric or self-centering chuck, in moving all jaws simultaneously

X. Describe the construction and principle of operation of the contracting chuck shown in Fig. 30.

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