215.
Which of the following describes
the cut of the threads in a screw
gear?
1.
One end has lefthand threads
and the other has righthand
threads
2.
Both ends have lefthand
threads
3.
Both ends have righthand
threads
4.
One end has a greater pitch and
less depth than the other
216.
Two Seamen are using a quadrant
davit to put a large lifeboat over
the side.
If the operating handle
is released while the boat is being
lowered, the boat is kept from
falling by means of
1.
a friction brake on the
operating handle
2.
a davit arm and swivel
3.
a counterweight
4.
selflocking threads on the
screw
2-17.
Gears serve all of the following
purposes EXCEPT
1.
eliminating frictional losses
2.
changing the direction of
motion
3.
increasing or decreasing the
applied force
4.
increasing or decreasing the
speed of the applied motion
2-18.
What condition must hold true if
two
1.
2.
3.
4.
gears are to mesh properly?
The teeth of both gears must be
the same size
Both gears must have the same
diameter
The teeth must be cut slanting
across the working faces of the
gears
The gears must turn on parallel
shafts
219.
Herringbone gears are sometimes
used instead of single helical
gears in order to
1.
change the direction of motion
2.
increase the mechanical
advantage
3.
increase the gear ratio
4.
prevent axial thrust on the
shaft
220.
If you should find it necessary to
transmit circular motion from a
shaft to a second shaft, which is
at right angles to the first shaft,
which of the following gear
arrangements should you use?
1.
Internal and pinion gears
2.
Miter gears
3.
Spur gears and idler
4.
Rack and pinion gears
221.
In a worm and spur gear
arrangement, the worm gear is
singlethreaded and has six
threads, and the spur gear has 30
teeth.
In order to turn the spur
gear one complete revolution, the
worm gear must be given how many
complete turns?
1.
5
2.
30
3.
50
4.
180
2-22.
If the worm gear in the worm and
spur gear arrangement in question
221 were triplethreaded, the
number of times the worm gear would
have to be turned in order to
produce one complete revolution of
the spur gear would be
1.
3 times
2.
10 times
3.
15 times
4.
60 times
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