# Engineering Metrology Questions and Answers – Gear Measurement

This set of Engineering Metrology Multiple Choice Questions & Answers (MCQs) focuses on “Gear Measurement”.

1. What is the effect of improper alignment of each tooth?
a) Tooth thickness increases
b) Face width decreases
c) Load will not distributed evenly
d) Pitch of teeth reduced

Explanation: Good alignment of each tooth on a gear is essential, as otherwise the load will not be distributed evenly over its face. It is quite probable that the load may be carried by one edge only introducing high bearing stresses, if teeth of a gear are machined poorly.

2. Which of the following is not true about concentricity of teeth?
a) Fluctuating velocity will be noticed when not concentric
b) Can be checked by using projector
c) Inaccuracy of parts when not concentric
d) Should be tested to ensure the proper heat treatment

Explanation: Concentricity of teeth is an important item and should be checked to ensure that the set up and equipment is in good order. When teeth are not concentric then fluctuating velocity will be noticed on the pitch line while transmitting motion.

3. Which of the following option is true about an analytical method of inspection of gears?
a) Analytical method is widely used for industries
b) This method is fast
c) All individual elements of gear teeth are checked
d) More accurate

Explanation: Analytical method is slow and tedious and not of much use for industry. By analytical inspection of gears we mean that all the individual elements of the gear teeth are checked. The discrete error values of pitch, tooth profile etc can’t give a true overall assessment of the accuracy of a gear.

4. Which of the following element is not determined by analytical inspection?
a) Profile
b) Composite vibrations
c) Spacing
d) Pitch

Explanation: The analytical inspection of the gears consists in determination of these Profile, Spacing, Pitch, Backlash, Runout or eccentricity or concentricity, thickness of tooth and Lead. These teeth elements in which the errors are caused due to manufacturing errors are determined by analytical inspection.

5. Which of the following option is correct for given statements about gear measurement?
Statement 1: Improper alignment of each teeth will cause high bearing stresses.
Statement 2: Gear blank should be tested for dimensional accuracy.
a) T, F
b) F, F
c) F, T
d) T, T

Explanation: The gear blank should be tested for dimensional accuracy and eccentricity as outside diameter forms the datum from where the tooth thickness is measured, it forms an important item to be controlled. It is quite probable that the load may be carried by one edge only introducing high bearing stresses, if teeth of a gear be machined poorly.
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6. Which of the following is not determined by the functional type of inspection?
b) Noise level
c) Variation in action
d) Vibration

Explanation: The functional inspection consists of carrying out the running test of gear with another gear which is more accurate and is known as master gear or control gear, to determine composite vibration, noise level, or variation in action.

7. Which of the following statement is true about inspection of gear?
a) Profile is determined by functional inspection
b) Backlash is determined by analytic inspection
c) Analytic test require running test of gear
d) Thickness of tooth is measured by functional inspection

Explanation: Functional type of inspection is done by running test of gear with another gear. It is used to determine noise level and composite variation. Analytical method is used to determine backlash, lead and runout.

8. Which of the following machine is used for rolling tests?
a) Parkson gear tester
b) Tooth caliper
c) Base pitch measuring instrument
d) Involute profile testing machine

Explanation: Rolling test is generally performed on Parkson Gear Tester. This test reveals any errors in pitch, tooth form and concentricity of pitch line. Any of the above errors will cause the variation of centre distance, when two gears are in mesh with each other.

9. If reference circle of gear is eccentric then which error is reflected by this eccentricity?
a) Cyclic error
b) Periodic error
c) Pitch error
d) Undulation

Explanation: It must be emphasised that there are some in-built limitations in the gear itself while the accuracy of measurement of gear depends upon the measuring equipment available, such as the inability of a gear to define its own axis of rotation. Thus if the reference circle of gear is eccentric, it would be reflected in pitch error.

10. Which of the following option is true for given statements about gear measurement?
Statement 1: There is no effect of cutter accuracy on the accuracy of gear.
Statement 2: Accuracy of individual elements is necessary for precision gears.
a) T, F
b) F, F
c) T, T
d) F, T

Explanation: The accuracy of any gear mainly depends upon the cutter accuracy and the setting of the machine. Optical projection and rolling tests will suffice for most of the gears. It is necessary to determine the accuracy of individual elements in the manufacture of high precision gears.

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