Machine Kinematics

Toothed Gearing

Question 1
Marks : +2 | -2
Pass Ratio : 25%
The condition of correct gearing is
pitch line velocities of teeth be same
radius of curvature of two profiles be same
common normal to the pitch surface cuts the line of centres at a fixed point
none of the mentioned
Explanation:
The fundamental condition of correct gearing is the common normal at the point of contact between a pair of teeth must always pass through the pitch point.
Question 2
Marks : +2 | -2
Pass Ratio : 100%
An imaginary circle which by pure rolling action, gives the same motion as the actual gear, is called
addendum circle
dedendum circle
pitch circle
clearance circle
Explanation:
Pitch circle is an imaginary circle which by pure rolling action, would give the same motion as the actual gear.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
The module is the reciprocal of
diametral pitch
circular pitch
pitch diameter
none of the mentioned
Explanation:
It is the ratio of the pitch circle diameter in millimeters to the number of teeth.
Question 4
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 5
Marks : +2 | -2
Pass Ratio : 50%
The ratio of face width to transverse pitch of a helical gear with α as the helix angle is normally
more than 1.15/tan α
more than 1.05/tan α
more than 1/tan α
none of the mentioned
Explanation:
None.
Question 6
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 7
Marks : +2 | -2
Pass Ratio : 33%
The two parallel and coplanar shafts are connected by gears having teeth parallel to the axis of the shaft. This arrangement is called
spur gearing
helical gearing
bevel gearing
spiral gearing
Explanation:
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.
Question 8
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 9
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.
Question 10
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.