Machine Kinematics

Toothed Gearing

Question 1
Marks : +2 | -2
Pass Ratio : 20%
Law of gearing is satisfied if
two surfaces slide smoothly
common normal at the point of contact passes through the pitch point on the line joining the centres of rotation
number of teeth = P.C.D. / module
addendum is greater than dedendum
Explanation:
Law of gearing says that 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 : 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 3
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 4
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 5
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 6
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 7
Marks : +2 | -2
Pass Ratio : 50%
Involute profile is preferred to cyloidal because
the profile is easy to cut
only one curve is required to cut
the rack has straight line profile and hence can be cut accurately
none of the mentioned
Explanation:
The face and flank of involute teeth are generated by a single curve where as in cycloidal
Question 8
Marks : +2 | -2
Pass Ratio : 33%
The radial distance of a tooth from the pitch circle to the bottom of the tooth, is called
dedendum
addendum
clearance
working depth
Explanation:
Addendum is the radial distance of a tooth from the pitch circle to the top of the tooth.
Question 9
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 10
Marks : +2 | -2
Pass Ratio : 20%
The maximum efficiency for spiral gears is
sin (θ + φ ) + 1/ cos (θ − φ ) + 1
cos (θ − φ) + 1/sin (θ + φ ) + 1
cos (θ + φ ) + 1/ cos (θ − φ ) + 1
cos (θ − φ) + 1/cos (θ + φ ) + 1
Explanation:
ηmax = cos (θ + φ ) + 1/ cos (θ − φ ) + 1