Machine Kinematics

Toothed Gearing

Question 1
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 2
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 3
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 4
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 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 : 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 7
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 8
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 9
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 10
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.