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40 Cards in this Set
- Front
- Back
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Gears are ______ forms of power transmission. |
positive
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Gears are used to: |
Change direction of rotation Increase/decrease speed of the driven shaft Increase/decrease torque of the driven shaft |
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The height of the gear tooth above the pitch circle is called: |
addendum |
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The distance equal to the addendum plus the dedendum minus the clearance |
Working depth |
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The distance from the center point of one gear tooth to the corresponding center point on the next gear tooth is called: |
pitch |
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In order to have two gears mesh properly they must each have: |
the same diametral pitch |
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What is the diametral pitch of a gear having 40 teeth and a 5 inch pitch diameter? |
8 |
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_____ is defined as the amount by which a tooth space exceeds the thickness of an engaging tooth. |
backlash |
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Identify the three shaft positions used with gears |
parallel intersecting at right angels crossing over |
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Spur gears are used to transmit power between: |
parallel shafts |
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How many teeth are in full mesh at any one time on spur gears? |
One |
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In which gear system do both the input and output shafts rotate in the same direction? |
internal spur gear |
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Which gear system uses both rotary and linear motion? |
rack and pinion |
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Spur gears produce ________ end thrust while in operation |
no |
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The angle that the helical gear tooth is on is referred to as the: |
Helix angle |
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With helical gears located on shafts that are parallel, the gears in mesh must |
have the same pressure angle have the same helix angle be of opposite hands |
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Direction of thrust produced by helical gears depends on: |
direction of the helix angle direction of gear rotation |
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Which gear system produces no axial thrust? |
Double helical gears herringbone gears |
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The ______ gear has no space separating the two opposed sets of teeth. |
herringbone |
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Which type of gears are cut on an angular surface that would be represented by a truncated cone? |
Bevel gears |
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Which types of bevel gearing are interchangeable and no equipment changes are required for thrust bearings? |
zerol bevel and straight bevel |
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Mitre gears are used: |
on shafts intersecting at right angles on one to one speed ratio drives |
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If the teeth of two meshed bevel gears are not flush on the back: |
the gears may be set with too much clearance excess backlash may exist |
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The hand of the spiral on spiral bevel gears is indicated by the direction in which the teeth curve |
away from the axis |
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Which types of gears are found on shafts which crossover each other at 90 degrees and never intersect? |
worm gear sets hypoid gears two helical gears of the same hand |
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Which hypoid gear, the pinion or the ring, has a larger spiral angle? |
pinion |
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As the lead angle of the worm increases, the pressure angle on the side of the worm's thread: |
is greater |
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The worm gear or wheel is the _____ and the worm is the _______ |
output - input |
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The distance one thread advances in one complete revolution of the worm is called: |
lead |
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What is the gear ratio when the worm gear has 48 teeth and the worm is double start? |
24:1 |
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The contacting patterns ,when the worm and worm gear are in proper position, depend on: |
whether the gear set is throated or non-throated |
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Which contact system provides for less tooth wear? |
throated worm gear set |
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Assembly of the worm and worm gear set is done by using gears: |
of the same hand |
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The thrust load and direction of thrust in a worm gear set: |
depends upon the position of the worm and worm gear set must be retained by using a bearing which can accept axial thrust depends on the direction of rotation of the worm |
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What is used to indicate the position of the worm gear in relation to the worm? |
a clear mesh pattern |
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Identify the three gears which make up a complete planetary gear system. |
Sun Planet pinions (carriers) ring |
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Planetary gear units are used for installations requiring: |
speed increase or decrease change in direction of rotation torque increase or decrease |
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When the planet carrier is driven and a brake is applied to the sun gear, determine the following: Which is the driver gear? Is it a speed reduction or increase? Is it a torque increase or decrease? |
Ring Reduction Increase |
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Backlash is defined as: |
the amount by which tooth space exceeds the thickness of an engaging tooth |
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Identify two main purposes of gear lubrication |
reduce friction transmit heat |
