6. Complete the sentences.

The term simple machine is often 1)____ those devices that change the direction or magnitude, or both, of an 2)____ force and thus do useful work. Among the simple machines is 3)____ plane. Machines are often 4)____ of their linkage systems. For exam­ple, an internal-combustion engine may be 5)____ by a four- link system called a slider crank The punch press is an example of a slightly more complicated device that 6)____ the slider crank and the four-bar linkage into a six-bar arrangement.

a) inclined, b) used to identify, d) applied, e) classified by the arrangement, c) described, f) combines.

7. Group the synonyms.

1)slant, 2)neglect, 3)slope, 4)lift, 5)inclination; 6)omit; 7)machine, 8)raise; 9)use, 10)linkage, 11)combined, 12)device; 13)application; 14)complex; 15)complicated, 16)connection; 17)transmit,18) translate, 19)deliver.

ELEMENTS OF MACHINES

UNIT 6

Fastener a mechanical device for fastening things together.

Pin a short, thin, sharp-pointed length of metal with a small head at one end used for fastening or holding things together.

Nut small piece of metal for screwing on to the end of the bolt.

Bolt a metal pin with a thread at one end for a nut.

Thread cutting on the fastener.

Text 1

1. Find in the text the names of fasteners, their description and classification. Read and translate the text. Kinds of Fasteners

A) The main standard threaded fasteners In­clude bolts, studs, screws and nuts. The design forms and geometrical ratios of the heads of bolts,

a b c d

Fig. 12 a., b. bolts. c. stud. d. screw nut.

screws and nuts are versatile indeed.

B). The choice of the design depends on the purpose of the joint. The heads may be hexagonal, square, co­untersunk, semi-circular, etc. They are also distinguished by the pre­sence of the area that restricts the rotation of the bolt in tightening (for example, bolts with a larger semi-circular head and a nib, and bolts with a hexagonal diminished head and a

C) guide underhead); by the method of clamping: externally, internally (with an internal hexagonal socket) on the end-face (heads with splines for a screw driver) and by other features. Depending оn the purpose of the joint, and the conditions of assembly, nuts are selected differing in form (hexagonal, ro­und, etc.), in thickness (normal, thin, thick).

D). In various threaded joints, nuts can take external expanding load which is compressive or tensile. The latter nuts are known as tension nuts and they be­long to the special design. Washers placed under heads or nuts, pro­tect the finished portion of the jointed members against damage during tighte­ning.