Learning Objective: Recognize the
importance of proper gear tooth
clearance and contact; describe the
methods used to check clearances
and tooth contact; and indicate what
corrective action may be necessary.
6-31.
Which of the following situations
requires that a main reduction gear be
given a wearing-in run before being run
at full power?
1.
New bearings have been installed
2.
Old bearings have been resurfaced
3.
The gears have been realigned
4.
The gear teeth have been stoned
6-32.
In main reduction gears, why is it
necessary to align gears and provide for
the proper clearances?
1.
To ensure uniform distribution of
pressure over the total area of the
tooth faces
2.
To prevent dirt and foreign matter
from entering the gears
3.
To ensure the proper appearance of
the gears
4.
To ensure that the proper oil
pressure is maintained
6-33.
When the original tooth contour is
destroyed, what type tooth contact takes
place?
1.
Rolling
2.
Metallic
3.
Rubbing
4.
Sliding
Question 6-34 is to be judged True or
False.
6-34.
Initial pitting of new gears may develop
during the wearing-in.
Slight pitting
does NOT affect the operation of the
gears.
6-35.
In reduction gears, the lead wire method
is most useful in measuring the
1.
depth of oil clearance
2.
extent of bearing wear
3.
designed root clearance
4.
irregularity of the bearing wear
Question 6-36 is to be judged True or
False.
6-36.
Noisy operation and insufficient contact
of the reduction gear teeth may result
unless the gear and pinion are properly
aligned.
6-37.
When you are checking the length of tooth
contact between reduction gear pinions
and gears, which of the following
substances is recommended for metal
coating?
1.
Potassium permanganate
2.
Zinc chromate
3.
Prussian blue
4.
Either 2 or 3 above
6-38.
Roughened gear teeth may be stoned smooth
provided the deterioration is due to
which of the following actions?
1.
Destructive pitting
2.
Foreign particles
3.
Initial pitting
4.
Backlash
6-39.
How should the high part of a reduction
gear tooth be checked?
1.
By inserting a feeler gauge between
the teeth
2.
By inserting a soft plastic wire
between the teeth
3.
By spotting-in with bluing
4.
By taking leads
6-40.
What percentages of the working surface
of a reduction gear tooth must show
contact to indicate a satisfactory tooth
bearing?
1.
95 percent of the axial length and 80
percent of the width
2.
80 percent of the axial length and
approximately 100 percent of the width
3.
100 percent of the axial length and
75 percent of the width
4.
75 percent of the axial length and
100 percent of the width
6-41.
What method should be used to remove a
high spot or deformation on a reduction
gear tooth?
1.
Scraping
2.
Stoning
3.
Lapping
4.
Filing
Learning Objective: Indicate the
function of a main thrust bearing
and the methods used to check end
play of a shaft.
39