Machine Kinematics Multiple Choice Questions on “Toothed Gearing – 1”.
1. The two parallel and coplanar shafts are connected by gears having teeth parallel to the axis of the shaft. This arrangement is called
a) spur gearing
b) helical gearing
c) bevel gearing
d) spiral gearing
Answer: a
Clarification: The two parallel and co-planar shafts connected by the gears. These gears are called spur gears and the arrangement is known as spur gearing. These gears have teeth parallel to the axis of the wheel as shown in Fig. 12.1. Another name given to the spur gearing is helical gearing, in which the teeth are inclined to the axis.
2. The type of gears used to connect two non-parallel non-intersecting shafts are
a) spur gears
b) helical gears
c) spiral gears
d) none of the mentioned
Answer: c
Clarification: The two non-intersecting and non-parallel i.e. non-coplanar shaft connected by gears. These gears are called skew bevel gears or spiral gears and the arrangement is known as skew bevel gearing or spiral gearing. This type of gearing also have a line contact, the rotation of which about the axes generates the two pitch surfaces known as hyperboloids.
3. An imaginary circle which by pure rolling action, gives the same motion as the actual gear, is called
a) addendum circle
b) dedendum circle
c) pitch circle
d) clearance circle
Answer: c
Clarification: Pitch circle is an imaginary circle which by pure rolling action, would give the same motion as the actual gear.
Addendum circle is the circle drawn through the top of the teeth and is concentric with the pitch circle.
Dedendum circle is the circle drawn through the bottom of the teeth. It is also called root circle.
4. The size of a gear is usually specified by
a) pressure angle
b) circular pitch
c) diametral pitch
d) pitch circle diameter
Answer: d
Clarification: Pitch circle diameter is the diameter of the pitch circle. The size of the gear is usually specified by the pitch circle diameter. It is also known as pitch diameter.
5. The radial distance of a tooth from the pitch circle to the bottom of the tooth, is called
a) dedendum
b) addendum
c) clearance
d) working depth
Answer: a
Clarification: Addendum is the radial distance of a tooth from the pitch circle to the top of the tooth.
Dedendum is the radial distance of a tooth from the pitch circle to the bottom of the tooth.
6. The product of the diametral pitch and circular pitch is equal to
a) 1
b) 1/π
c) π
d) 2π
Answer: c
Clarification: Diametral pitch, pd = T/D = π/pc
where, pc = circular pitch.
7. The module is the reciprocal of
a) diametral pitch
b) circular pitch
c) pitch diameter
d) none of the mentioned
Answer: a
Clarification: It is the ratio of the pitch circle diameter in millimeters to the number of teeth.
It is usually denoted by m. Mathematically,
Module, m = D /T.
8. Which is the incorrect relationship of gears?
a) Circular pitch × Diametral pitch = π
b) Module = P.C.D/No.of teeth
c) Dedendum = 1.157 module
d) Addendum = 2.157 module
Answer: d
Clarification: None.
9. If the module of a gear be m, the number of teeth T and pitch circle diameter D, then
a) m = D/T
b) D = T/m
c) m = D/2T
d) none of the mentioned
Answer: a
Clarification: Module, m = D /T.
10. Mitre gears are used for
a) great speed reduction
b) equal speed
c) minimum axial thrust
d) minimum backlash
Answer: b
Clarification: When equal bevel gears (having equal teeth) connect two shafts whose axes are mutually perpendicular, then the bevel gears are known as mitres.