Machine Kinematics

Toothed Gearing

Question 1
Marks : +2 | -2
Pass Ratio : 20%
The size of a gear is usually specified by
pressure angle
circular pitch
diametral pitch
pitch circle diameter
Explanation:
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.
Question 2
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 3
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 4
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 5
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 6
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 7
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 8
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 9
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 10
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