Power Transmission Review Flashcards
The LEAD and the PITCH of a WORM are the same when:
If it has a single start
In what shaft positions are the cross dial sweep readings taken and recorded?
In four planes at 12, 3, 6, and 9 o’clock
When checking backlash you should place the dial indicator button on the worm wheel tooth:
At the pitch line
If the input power is on the sun gear and the carrier is locked to the sun, the output will be a forward reduction?
False (Reverse low)
Driver: Sun, Driven: Carrier, Held, Ring. Final Output?
Reduction (low)
Driver: Sun, Driven: Ring, Held, Carrier. Final Output?
Reverse (low)
Driver: Carrier, Driven: Ring, Held, Sun. Final Output?
Overdrive (normal)
Driver: Carrier, Driven: Sun, Held, Ring. Final Output?
Overdrive (high)
Driver: Ring, Driven: Carrier, Held, Sun. Final Output?
Reduction
Driver: Ring, Driven: Sun, Held, Carrier. Final Output?
Reverse (overdrive)
Driver, Driven and held. Two members are locked together
Direct drive
In a planetary system if none of the planetary members are held, what is the result of the Final output?
Neutral
One advantage when using the cross dial method is?
It eliminates error caused by axial float
TorF. The pinion gear is usually the smallest gear in the set.
True
Which dialing alignment procedure has concerns with shaft end float error?
Rim and face alignment
Why is a good mesh pattern important to the life of a gearbox?
So that there is even distribution of load on the teeth
When performing CROSS DIAL alignment, the distance between dial indicators should never be less than:
4”
The backlash setting in worm and worm wheel reducers that frequently start, stop and reverse should be?
A minimum value
How much backlash should there be between spur gears with a diametral pitch of 8?
0.005” Backlash=0.040/DP
In a speed increasing gearbox: Output speed (Increases or Decreases) and output Torque (increases or decreases)
Output speed increases, output torque decreases
When checking for coupling rim runout, the high spot on the rim causes the dial to:
Move to a positive value
What are shims used for in a gearbox?
To adjust mesh pattern and end float
When single helical gears mesh, the thrust developed in a driven gear in relation to the thrust developed in the drive gear is always in which direction. (Direction and plane (axial or radial))
Opposite direction axially
Gear tooth clearance can be mathematically worked out by the following.
Whole depth-working depth
Why is residual magnetism dangerous to rebuilt gearboxes?
Attracts iron particles to wear surfaces
Before a precise alignment is started, the machines should be roughly lined up horizontally within how close of true position.
10 mils (0.25mm)
TorF. A drive using helical gears can have the gears set up for the are overhung
True
Before starting to take a set of cross dial sweep readings it is suggested that: (Where to zero the A and B Dials)
“A” be zeroed at the top and B at the bottom
Overhauled gearboxes should be fitted with magnetic drain plugs and
Visual oil sight glasses
Two gears will only MESH if they have the SAME:
Diametral pitch
Rim dial runout readings are taken with the dial button reading on
Rotated rim
A SUN gear is one of the components of a _______ gear set?
Planetary
Hold-down bolts can be necked down to:
?????
What type of gear is conical in shape (Cone shaped)
Bevel
In order to have accurate FACE READINGS, it is very important to arrest:
Axial Float
TorF. A gearbox has a 10:1 reduction by a 1 hp electric motor at 1750 RPM. The output from the gearbox will be 10 hp at a speed of about 175 rpm.
False (HP is constant)
TorF. Gears are positive power transmission devices that are used where there can be no slippage.
True
TorF. Magnetism in gears and bearings can be checked with a compass.
True
As the Diametral Pitch of a gear increases, does the tooth size increase or decrease?
Tooth size decreases
When performing a cross dial alignment, the “A” dial must be reading on the (Fixed or Moveable; Face or Rim)
Fixed component rim
What is a mating gear mesh pattern?
The shiny metallic surfaces that shows up when on tooth drives another.
Why would the “A” and “B” Dials be mounted a minimum distance apart from each other?
X distance should be larger to increase accuracy.
The best set of dial brackets would be
free of sag by design
Excess “backlash” can be an indicator that the gear teeth are?
Wearing
The correct term for the condition whereby a machine does not sit properly on all its mounting feet is:
Soft foot
This type of gear set has a 1:1 ratio and always intersects at 90 degrees
Mitre
Which of the following would cause a dial to indicate some rim runout movement?
A true bored hub
A straight shaft
The dial button not touching
A hammered-on coupling
A hammered on coupling
TorF. If there are several gear reductions in a gearbox, with ratios of 4:1. 5:1 and 2.5:1, the final reduction of the gearbox will be 45:1
False, it would be 50 (4x5x2.5)
TorF. Hypoid gears have high sliding action and require an EP additive in the oil?
True. Hypoid gears have extensive sliding action which increases friction and requires lubricants containing express pressure (EP) additives whuich as sulphur or phosphorus compounds to increase the oil film strength.
To what does the gear term “backlash” refer?
Arc clearance between mounted, mating gears
To correct angular and parallel coupling misalignment at the same time use the following procedure
Two dial procedure where the dials are mounted 180 degrees opposite each other, one dial reading on the moveable coupling rim and the other reading on the fixed coupling rim.
Rim dial indicator readings are taken off a coupling:
90 degrees to the shaft axis.
TorF. Most gears are be made to the standards set by the AGMA
True
On a RIM reading, the sum of the 12 & 6 o’clock readings must always ________ the sum of the 3&9 o’clock readings.
Equal
Which of the following is not a method of checking mesh patterns?
Pencil lead
Prussian Blue
Black light and dye
Feeler gauges
Feeler gauges
TorF. A planetary gear system can be considered a single reduction unit?
False
Gear mesh is normally checked with
Dye
Dial bracket sag can be checked using:
A hollow cylindrical shaft
Mesh patterns can be corrected by
Bearing shims in worm and worm wheel gear sets
Turning both shafts during an alignment procedure eliminates error due to:
Runout
Soft foot can be checked with
A dial indicator mounted on the moveable base
A gear train has 15 gears meshing together with the input gear rotation in the CW direction. The output gear should turn in the CCW direction.
False
Plastic shims are colour-coded to identify
Thickness
One advantage of using the cross dial procedure is that the readings will not be incorrect because of error from
End float
The worm wheel will advance three teeth per revolution of the worm when the worm has how many starts?
Triple start
In a gear reduction unit the output shaft generally _________ that the input shaft:
Larger
Misalignment can cause
Vibration
A dial indicator is going to be used to do an external check for backlash. Where should the plunger be set?
At the same radius as the pitch diameter
When performing a “RIM and FACE” alignment, Angular misalignment is measured:
On the coupling face
The lead and pitch of a worm are the same when
It has a single start
The most common type of misalignment is
combination
The strongest gear tooth pressure angle is _______ degrees.
59
60
20
14.5
20
This type of gear set converts rotary motion to linear motion.
Rack and pinion
TorF. Brass gears can become magnetized?
False. Copper alloy therefor non-ferrous
TorF. A gear with a diametral pitch of 4 has very small teeth.
False. The smaller the DP the larger the gear tooth size
A gear train has an even number of gears. The input gear is spinning counter clockwise. What direction will the output gear spin?
Clockwise
Offset alignment is also known as
Parallel Alignment
To what does the gear term “backlash” refer to?
Total clearance between mounted, mating gears
If the face dial indicator is set up on the back side of a coupling for a rim and face alignment: What will change
Only the sign of the TIR will change
If bar sag check reading is -0.003 the dial indicator should be set to _____ at the 12 o’clock position.
-0.003
Backlash can be checked within helical gearboxes by using the lead wire procedure. What is this procedure?
Run thin lead wire between mating gear teeth; then recover the wire and measure the thickness at the deformed regions.
The difference in the values of dial indicator readings taken 180 degrees apart is known as:
TIR
A double throated worm and worm wheel great set will have the maximum gear tooth contact.
True
Eccentricity of a shaft is also known as:
Runout
The best type of coupling to use when shafts do not share a common centerline is:
A universal joint
The most reliable method of ensuring that an alignment is satisfactory under operating conditions is.
Vibration analysis equipment
Why should all gearbox shafts be checked for straightness?
Bent shafts cause varying mesh patterns and backlashes.
ToF. In a compound gear system there can be six gears and four shafts.
True
A spur gear set that intersects at 90 deg must be at the same hand.
False
