1. The smaller and generally the driving gear of a pair of mated gears is called _________
a) pitch
b) module
c) rack
d) pinion
Explanation: Pinion is the smaller and the driving gear of a pair of mated gears. It is used in gear train drives and is usually the smaller gear. The pinion engages the larger gear or rack that helps in the turning of the wheels of the vehicle.
2. The distance measured along the circumference of the pitch circle from a point on one tooth to the same point on the adjacent tooth is called ________________
a) pitch diameter
b) circular pitch
c) pitch point
d) line of centres
Explanation: Circular pitch is the distance measured along the circumference of the pitch circle from a point on one tooth to the same point on the adjacent tooth. So basically, it is the distance between corresponding points of consecutive gear teeth.
p = d π/ N; where, p is the circular pitch, d is the standard pitch diameter and N is the number of teeth
3. The number of teeth per unit length of the pitch circle diameter is called ________________
a) diametral pitch
b) module
c) clearance
d) gear ratio
Explanation: Diametral pitch is the number of teeth per unit length of the pitch circle diameter.
It is used to classify different types and sizes of gears. It is a function of the pitch circle.
P = T/d.
4. The ratio of the number of teeth on the gear to the number of teeth on the pinion is called ______
a) velocity ratio
b) module
c) gear ratio
d) pitch point
Explanation: Gear ratio is given by T/t and is defined as the ratio of the number of teeth on the gear to the number of teeth on the pinion. Velocity ratio is the inverse of gear ratio.
Gear ratio is inversely proportional to the radius of the pitch circle and also the number of teeth on the driving gear
5.The ratio of pitch diameter to the number of teeth is called _________
a) module
b) addendum
c) dedendum
d) backlash
Explanation: Module is the ratio of pitch diameter to the number of teeth.
Module indicates the size of the gear and classifies whether the gear is big or small as module is a unit of size.
m = d/T or m = p/π.
6. The circle passing through the upper tips of the teeth is called _________________
a) pitch circle
b) circular pitch
c) dedendum circle
d) addendum circle
Explanation: Addendum circle is the circle passing through the upper tips of the teeth. The addendum circle lies on the outside cylinder for external gears whereas the addendum circle lies on the internal cylinder for internal gears. The diameter for the addendum circle of an internal gear is called as inside diameter.
7. The radial height of a tooth above the pitch circle is called ____________
a) addendum
b) dedendum
c) rack
d) line of centres
Explanation: Addendum is the radial height of a tooth above the pitch circle. Basically, it is the radial distance between pitch diameter and diameter of the outside circle. Addendum angle is the angle between the face cone and the pitch cone.
8.The circle passing through the roots of the teeth is called ________________
a) addendum
b) addendum circle
c) dedendum circle
d) rack
Explanation: Dedendum circle is the circle passing through the roots of the teeth. It touches the bottom of the spaces between the teeth of a gear.
9. The radial depth of a tooth below the pitch circle is called _______________
a) dedendum
b) addendum
c) rack
d) line of centres
Explanation: Dedendum is the radial depth of a tooth below the pitch circle. It is the radial distance between the pitch circle and the root circle. Dedendum angle is the angle between the root cone and the pitch cone.
10. The radial difference between the addendum and the dedendum of the tooth is called _________
a) clearance
b) rack
c) line of action
d) line of centres
Explanation: Clearance is the radial difference between addendum and dedendum of the tooth. Clearance circle is a tangent to the addendum circle on the gear. It has a clearance which equal to the distance between the dedendum of the gear and the addendum of the mating gear