Machine Kinematics

Toothed Gearing

Question 1
Marks : +2 | -2
Pass Ratio : 20%
Interference can be avoided in involute gears with 20° pressure angle by
cutting involute correctly
using as small number of teeth as possible
using more than 20 teeth
using more than 8 teeth
Explanation:
None.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
For a speed ratio of 100, smallest gear box is obtained by using
a pair of spur gears
a pair of helical and a pair of spur gear compounded
a pair of bevel and a pair of spur gear compounded
a pair of helical and a pair of worm gear compounded
Explanation:
None.
Question 3
Marks : +2 | -2
Pass Ratio : 40%
The contact ratio for gears is
zero
less than one
greater than one
none of the mentioned
Explanation:
The theoretical minimum value for the contact ratio is one, that is there must always be at least one pair of teeth in contact for continuous action.
Question 4
Marks : +2 | -2
Pass Ratio : 33%
The product of the diametral pitch and circular pitch is equal to
1
1/Ï€
Ï€
2Ï€
Explanation:
Diametral pitch, pd = T/D = π/pc
Question 5
Marks : +2 | -2
Pass Ratio : 50%
The type of gears used to connect two non-parallel non-intersecting shafts are
spur gears
helical gears
spiral gears
none of the mentioned
Explanation:
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.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
If the module of a gear be m, the number of teeth T and pitch circle diameter D, then
m = D/T
D = T/m
m = D/2T
none of the mentioned
Explanation:
Module, m = D /T.
Question 7
Marks : +2 | -2
Pass Ratio : 50%
Mitre gears are used for
great speed reduction
equal speed
minimum axial thrust
minimum backlash
Explanation:
When equal bevel gears (having equal teeth) connect two shafts whose axes are mutually perpendicular, then the bevel gears are known as mitres.
Question 8
Marks : +2 | -2
Pass Ratio : 50%
The maximum length of arc of contact for two mating gears, in order to avoid interference, is
(r + R) sin φ
(r + R) cos φ
(r + R) tan φ
none of the mentioned
Explanation:
Interference may only be prevented, if the addendum circles of the two mating gears cut the
Question 9
Marks : +2 | -2
Pass Ratio : 100%
When the addenda on pinion and wheel is such that the path of approach and path of recess are half of their maximum possible values, then the length of the path of contact is given by
(r + R) sin φ/2
(r + R) cos φ/2
(r + R) tan φ/2
(r + R) cot φ/2
Explanation:
In case the addenda on pinion and wheel is such that the path of approach and path of recess are half of their maximum possible values, then
Question 10
Marks : +2 | -2
Pass Ratio : 33%
Which is the incorrect relationship of gears?
Circular pitch × Diametral pitch = π
Module = P.C.D/No.of teeth
Dedendum = 1.157 module
Addendum = 2.157 module
Explanation:
None.