UNIT 15 – GEARS
gear n. /'giə/ - a toothed wheel that engages with another toothed wheel in order to
change the speed or direction of transmitted motion
tooth n. /'tu:θ/ (plural teeth /'ti:θ/) - any one of a number of uniform projections on a
gear, sprocket, rack, etc, by which drive is transmitted
toothed wheel n. /tu:θt wi:l/ - a wheel with teeth
mesh v. /'me∫/ - (of gear teeth) to engage
shaft n. /'∫a:ft/ - a revolving rod that transmits motion or power
axis n. /'æksis/ (plural axes /'æksi:z/ - one of two or three reference lines used in
coordinate geometry to locate a point in a plane or in space
arrangement n. /ə'reindʒmənt/ - the form in which things are arranged
rack-and-pinion n. - a device for converting rotary into linear motion and vice versa, in
which a gearwheel (the pinion) engages with a flat toothed bar (the rack)
pinion n. /'pinjən/ - a cogwheel that engages with a larger wheel or rack
bar n. /'ba:/ - a rigid usually straight length of metal, wood, etc
rack n. /'ræk/ - a toothed bar designed to engage a pinion to form a mechanism that will
interconvert rotary and rectilinear motions
longitudinal adj. /‚londʒi'tju:dinəl; ‚loŋgi'tju:dinəl/ - of or relating to longitude or length
spur gear n. /'spз: giə/ (=spur wheel) - a gear having teeth either straight or helically
cut on a cylindrical surface
helical gear n. /'helikəl giə/ - a cylindrical gearwheel having the tooth form generated on
a helical path about the axis of the wheel
double helical gear n. (=herringbone gear /'heriŋ‚bəun/) - a gearwheel having two
sets of helical teeth, one set inclined at an acute angle to the other so that V-shaped
teeth are formed
bevel gear n. /'bevəl giə/ - a gear having teeth cut into a conical surface known as the
pitch zone
worm gear n. /'wз:m giə/ - a device consisting of a threaded shaft (worm) that mates
with a gearwheel (worm wheel) so that rotary motion can be transferred between two
shafts at right angles to each other
gearing n. /'giəriŋ/ - an assembly of gears designed to transmit motion
friction loss n. /'frik∫ən los/ - the power lost overcoming the friction between two moving
surfaces
pitch n. /'pit∫/ - the distance between corresponding points on adjacent members of a
body of regular form, esp the distance between teeth on a gearwheel or between
threads on a screw thread
lubrication n. /‚lu:bri'kei∫ən/ - the act of lubricating something
score n. /'sko:/ - to make (cuts, lines, etc) in or on
lubricant n. /'lu:brikənt/ - a lubricating substance, such as oil
maintain v. /mein'tein/ - to continue or retain; keep in existence
penetrate v. /'peni‚treit/ - to find or force a way into or through (something); enter
grit n. /'grit/ - small hard particles of sand, earth, stone, etc
suspension n. /sə'spen∫ən/ - a system of springs, shock absorbers, etc, that supports
the body of a wheeled or tracked vehicle and insulates it and its occupants from shocks
transmitted by the wheels
alignment n. /ə'lainmənt/ - proper or desirable coordination or relation of components
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Easily confused words:
worm n. /'wз:m/ - any of various insect larvae having an elongated body, such as the
silkworm and wireworm
warm adj. /'wo:m/ - characterized by or having a moderate degree of heat; moderately
hot
carry v. /'kæri/ - to take or bear (something) from one place to another
care v. /'keə/ - to be troubled or concerned
NOTE: FOREIGN PLURAL
In scientific English there are a large number of words borrowed from other languages.
They have been absorbed into the language, but they have not been thoroughly
'naturalised'. Usually they retain their original foreign plural forms. The largest number of
these foreign plurals is of Latin or Greek origin. Here is the list of nouns of foreign origin
with their foreign and regular plurals:
Singular
Foreign plural
Regular plural
analysis /ə'nælisis/
analyses /ə'nælisi:z/
axis /'æksis/
axes /'æksi:z/
basis /'beisis/
bases /'beisi:z/
crisis /'kraisis/
crises /'kraisi:z/
diagnosis /ˌdaiəg'nəusis/
diagnoses /ˌdaiəg'nəusi:z/
hypothesis /hai'poθisis/
hypotheses /hai'poθisi:z/
oasis /əu'eisis/
oases /əu'eisi:z/
thesis /'θi:sis/
theses /'θi:si:z/
criterion /ˌkrai'tiəriən/
criteria /ˌkrai'tiəriə/
criterions
bacterium /ˌbæk'tiəriəm/
bacteria /ˌbæk'tiəriə/
maximum /'mæksiməm/
maxima /'mæksimə/
maximums
millenium /mi'leniəm/
millenia /mi'leniə/
minimum /'miniməm/
minima /'minimə/
minimums
stratum /'stra:təm/
strata /'streitə/
stratums
symposium /sim'pəuziəm/
symposia / sim'pəuziə/
symposiums
phenomenon /fi'nominən/
phenomena /fi'nominə/
phenomenons
formula /'fo:mjulə/
formulae /'fo:mjuli/
formulas
radius /'reidiəs/
radii /'reidiai/
radiuses
stimulus /'stimjuləs/
stimuli /'stimjulai/
syllabus /'siləbəs/
sillabi /'siləbai/
sillabuses
datum /'deitəm/
data /'deitə/
curriculum vita /kju'rikjulum 'vi:tə/ curricula vitae /kju'rikjulə 'vi:tai/ curriculums
focus /'fəukəs/
foci /' fəusai/
focuses
In some cases the two plurals have different meanings:
index /'indeks/
indices /'indisi:z/ = algebraic signs
indexes /'indeksiz/ = tables of contents
genius /'dʒi:niəs/
genii /'dʒi:niai/ = spirits
geniuses /'dʒi:niəsiz/ = highly intelligent persons
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medium /'mi:diəm/
media /'mi:diə/ = means of communication
mediums /'mi:diəmz/ = people claiming communication with
spirits
EXERCISES:
A) Complete the following sentences with nouns in the plural.
1. Travellers in the desert still depend on ______________ for water. (oasis)
2. An eclipse of the sun is one of the numerous natural ______________ that used to
frighten people. (phenomenon)
3. What are your ______________ in judging an economic program? (criterion)
4. The scientist published the results of his experiment after he had completed all his
______________ in the laboratory. (analysis)
5. There will be several ______________ on ecology next autumn. (symposium)
6. The plural form of stimulus is ______________.
7. Popular singers in Britain come from various ______________ of society. (stratum)
8. The educational authorities have made changes in the elementary and secondary
school ______________ for next year. (syllabus)
9. Your ______________ are not correct. You can't support them with any of your
arguments. (thesis)
10. Several antibiotics are very effective against a wide spectrum of ______________
(bacterium).
11. The two doctors gave two different ______________ of the patient's illness. The
patient decided to go to a third specialist. (diagnosis)
12. Communications ______________ play an important role in present-day society.
(medium)
13. Circles of different size have different ______________. (radius)
B) Answer the questions.
1. Define gears.
2. What are gears used for?
3. What are two types of teeth arrangement?
4. What does rack and pinion serve for?
5. What are the commonest types of gears?
6. What is the most important factor in the efficiency of gears?
C) True or false?
1. Gears are used to transmit rotary motion or power from one shaft to another.
2. The rotation speeds of the shafts are directly proportional to the numbers of teeth on
their gears.
3. Teeth may be internal or external.
4. Rack and pinion gearing is used to convert rotary motion into longitudinal motion or
vice versa.
5. Gears should have an efficiency of 98% or more.
6. Efficiency of gears does not depend on lubrication.
7. A small amount of lubricant must be applied to the meshing gears.
8. A good pair of gears may have an indefinite life.
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D) Match the terms and definitions.
1. efficiency
A) a lubricating substance, such as oil
2. axis
B) the form in which things are arranged
3. suspension
C) a number of uniform projections on a gear
4. lubricant
D) a toothed wheel
5. arrangement
E) a revolving rod that transmits motion or power
6. friction
F) the ratio of the useful work done by a machine, engine, device,
etc., to the energy supplied to it
7. teeth
G) a system of springs, shock absorbers, etc, that supports the
body of a wheeled or tracked vehicle
8. gear
H) a force that resists the relative motion of two bodies or
substances in contact
9. shaft
I) a straight line about which a body or geometric object rotates or
may be conceived to rotate
E) Match the term and image.
worm gears
rack and pinion
spur gears
bevel gears
herringbone gears
helical gears
F) Put the verbs in brackets into the correct -ed or -ing form.
1. When two _____________ (mesh) gears have external teeth, then their shafts rotate
in opposite directions.
2. _____________ (cross) axis helical gears have many functions.
3. There is a _____________ (limit) number of gear types.
4. The _____________ (cut) action of the hob generates uniform worm wheel teeth.
5. The _____________ (power-transmit) capacity of worm gearing is based on several
factors.
6. Lubrication must be repeated at _____________ (give) times.
7. The nature of tooth engagement in worm gearing causes a greater _____________
(slide) action between the surfaces in contact than in the case of spur gearing.
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