ВУЗ:
Составители:
Рубрика:
36
III. TYPES OF GEARS
Study of gear terminology
Types of gears. Classification. Basic elements of gears.
Methodical materials:
- non-adapted texts:
a) textbooks,
b) references,
c) periodical scientific and popular-science editions;
- models of mechanisms;
- pictures of gear elements, gear mechanisms, schemes of mechanisms;
- tasks and exercises on theme.
This chapter will address gear geometry, the kinematic relations, and the
consequential forces and moments associated with the four principal types of
gears. The forces and moments are transmitted to meshing gears and to the
shafts and bearings to which they are attached. The torsion moment allows
motion and power transmission. Other moments and forces affect the shaft
and its bearings. The next two chapters will address stress, strength, safety,
and reliability.
Types of Gears
Spur gears, illustrated in Fig. III.1, have teeth parallel to the axis of rotation
and are used to transmit motion from one shaft to another, parallel, shaft. Of
all types, the spur gear is the simplest and, for this reason, will be used to
develop the primary kinematic relationships of the tooth form.
Helical gears, shown in Fig. III.2, have teeth inclined to the axis of rotation.
Helical gears can be used for the same applications as spur gears and, when
so used, are not as noisy, because of the more gradual engagement of the
teeth during meshing. The inclined tooth also develops thrust loads and
bending couples, which are not present with spur gearing. Sometimes helical
gears are used to transmit motion between nonparallel shafts.
Bevel gears, shown in Fig. III.3, have teeth formed on conical surfaces and
are used mostly for transmitting motion between intersecting shafts. The
figure actually illustrates straight-tooth bevel gears. Spiral bevel gears are
cut so the tooth is no longer straight but forms a circular arc. Hypoid gears
are quite similar to spiral bevel gears except that the shafts are offset and
nonintersecting.
Страницы
- « первая
- ‹ предыдущая
- …
- 34
- 35
- 36
- 37
- 38
- …
- следующая ›
- последняя »
