Module - Gearing Installation & Maintenance Flashcards Preview

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Flashcards in Module - Gearing Installation & Maintenance Deck (47):
1


What is the name of the organization that develops guidelines and standards for gears in North America?


American Gear Manufacturers Association

2


You have been given a work order asking you to work on a small gear train. What should you do first regarding immobilizing the machine?


isolate and lock out the machine

3


Why is it impossible to shut some gear drives down for maintenance?


Damage from heat may occur.

4


If someone asks you to remove safety guards while the machine is running, what should you recommend?


Safety guards should never be removed while units are running.

5


What are two common methods of lubricating open gear sets?


by drop and force-feed systems

6


How can you check the backlash in a large open gear set (with the unit shutdown)?


by placing the largest feeler gauge that will fit between the mating gears

7


What symptoms appear when a gear set is adjusted with less than minimum backlash?


The gears give off a loud whining sound.

8


How does potential energy stored in a shut down machine pose a threat to the person assigned to work on the machine's main input gear reducers?


The output coupling may be under torsion forces that could entangle the worker when the coupling is mechanically disconnected.

9


What safety precaution should be taken before disconnecting a chain drive from a gear reducer to a loaded bucket elevator?


Contact the operator and have the elevator unloaded before locking it out.

10


How are shaft-mounted reducers fastened to the shafts they drive?


by keys and set screws

11


Why should you use a torque arm on a shaft-mounted reducer?


to prevent gearbox rotation

12


Some shaft-mounted reducers use a device to absorb torsion load shock. What device do gearbox manufacturers use to do this?


spring type torque arms

13


What is the proper positioning for the torque arm installed with a shaft-mounted reducer?


Install the torque arm 90° from a line running from the output shaft to the point of attachment.

14


How can you make slight speed ratio changes on shaft-mounted speed reducer drives?


Change the motor drive sheave or reducer input sheave size

15


Why are match marks placed on gearboxes?


for ease of reassembly

16


What should be done to the top cover of a gearbox to make the cover break free of the bottom?


Drill and tap the top cover flange and install jacking bolts.

17


Why do you not use hardened steel wedges between the split joint of a gearbox for removal purposes?


You may damage or break the cover.

18


Why should you give a close inspection to the inside of the top cover?


Inspection can reveal problems, such as contamination.

19


Why should all gearbox shafts be checked for straightness?
a) Bends in shafts cause varying mesh patterns and backlashes.
b) Straightness of shafts is necessary for full film lubrication.
c) If shafts are straight, they align easily.
d) Bent shafts must be replaced with straight shafts.


a) Bends in shafts cause varying mesh patterns and backlashes.

20


What is a good way to check a shaft for straightness?


Use a dial indicator and magnetic base with shaft mounted on V-blocks.

21


Most industrial plant overhaul shops require that the gearbox bearings:
a) be inspected and reused if in good condition.
b) be cleaned, inspected for wear and reused if in good condition.
c) be cleaned and inspected for electrical arcing and then discarded.
d) be replaced with new bearings.


d) be replaced with new bearings.

22


How could a gear tooth be measured for amount of wear?
a) Use an outside caliper.
b) Use an outside micrometer.
c) Use a vernier gear tooth measuring tool.
d) Use a gear pitch gauge.


c) Use a vernier gear tooth measuring tool.

23


One-direction drive gears can be pressed off a shaft and turned 180° because:
a) there is little or no wear on the non-drive side.
b) reversing the gear replaces worm drive teeth with new teeth.
c) reversing the gear places the unworn gear tooth side in contact with the mating gear.
d) the gear is worn on the drive side only.


c) reversing the gear places the unworn gear tooth side in contact with the mating gear.

24


Why would you check all gear box components for residual magnetism?
a) Residual magnetism attracts iron particles to mating surfaces, causing wear.
b) Residual magnetism creates localized hot spots.
c) Magnetic particles can reduce mechanical clearances.
d) Magnetic particles speed up oil oxidation.


a) Residual magnetism attracts iron particles to mating surfaces, causing wear.

25


The mating surfaces of the split joint of a gearbox can be cleaned and deburred by:
a) using a small belt sander.
b) hand oilstoning the surfaces with oil as a lubricant.
c) surface grinding.
d) draw filing.


b) hand oilstoning the surfaces with oil as a lubricant.

26


Pulled-up female threads in the lower split joint surface can be removed by:
a) grinding.
b) drilling.
c) countersinking.
d) reaming.


c) countersinking.

27


To what does the gear term "backlash" refer?
a) gear end float
b) shaft and gear end float
c) radial tooth tip to root clearance measured outside the pitch circle
d) arc clearance between mounted, mating gears


d) arc clearance between mounted, mating gears

28


Tooth wear on a worm wheel causes:
a) more heat to be generated.
b) more backlash.
c) less backlash.
d) zero backlash.


b) more backlash.

29


The backlash setting in worm and worm wheel reducers that frequently start, stop and reverse is:
a) a large value.
b) a maximum value.
c) a minimum value.
d) an average value.


c) a minimum value.

30


When checking backlash you should place the dial indicator button on the worm wheel tooth:
a) at the tooth base.
b) at the pitch line.
c) at the tooth flank.
d) anywhere on the tooth drive side.


b) at the pitch line.

31


Backlash can be checked within helical gearboxes by using the lead wire procedure. What is this procedure?
a) Place the lead wire onto the gears; then replace the cover to squeeze the lead.
b) Run thin lead wire between mating gear teeth; then recover the wire and measure the thickness at the deformed regions.
c) Place the lead wire in the root of one gear and then turn the mating gear over so that the tip of one gear tooth deforms the lead. Remove the lead wire and measure the deformed thickness.
d) Stretch a piece of lead wire until it becomes thin enough to place between mating teeth and then measure the wire.


b) Run thin lead wire between mating gear teeth; then recover the wire and measure the thickness at the deformed regions.

32


Excess backlash can be an indicator that the gear teeth are:
a) wearing.
b) pitting.
c) scoring.
d) flaking.


a) wearing.

33


Why should you use several sets of feeler gauges between the bearing caps and the casings when setting shaft end floats?
a) Using feeler gauges avoids the necessity of cutting trial and error shims, which is time consuming.
b) Feeler gauges are less expensive than cutting shims.
c) Feeler gauges allow slight tapers to be built into the fit between the large cap and the casing.
d) Feeler gauges are better static seals.


a) Using feeler gauges avoids the necessity of cutting trial and error shims, which is time consuming.

34


What is a mating gear mesh pattern?
a) the area that does not rub when two gears mesh
b) the area on the non-drive side of the teeth, where oil collects
c) the shiny metallic surfaces that show up when one tooth drives another
d) a blue area that shows up on the drive side of mating teeth and that is caused by heat and extreme pressure


c) the shiny metallic surfaces that show up when one tooth drives another.

35


A good mesh pattern between gears that are mated is indicated by:
a) patterns showing at the extreme edges.
b) patterns showing at opposite edges.
c) a central tooth pattern not contacting on either edge.
d) a dial indicator mounted at the pitch line and the gear rocked back and forth.


c) a central tooth pattern not contacting on either edge.

36


Mesh patterns can be corrected by:
a) bearing shims in worm and worm wheel gear sets.
b) remachining bearing housings in helical gear sets.
c) preloading the worm bearings in a worm and worm wheel gearbox.
d) replacing the worm wheel in a worm and worm wheel reducer.

a) bearing shims in worm and worm wheel gear sets.

37


Which of the following is not a method of checking mesh patterns?
a) feeler gauges
b) pencil lead
c) black light and dye
d) Prussian blue

a) feeler gauges

38


Why is a good mesh pattern important to the life of a gearbox?
a) Mesh patterns alter bearing loads.
b) Mesh patterns allow oil full film lubrication.
c) Mesh patterns change as the gear set is loaded.
d) Mesh patterns increase backlash.

b) Mesh patterns allow oil full film lubrication.

39


A helical gearbox mesh pattern checked with bluing can be saved and recorded in a maintenance report by:
a) photographing.
b) removing with fibreglass tape.
c) removing with transparent tape that has been profiled and numbered.
d) a simple sketch.

c) removing with transparent tape that has been profiled and numbered.

40


What is tolerance stackup?
a) slight errors in machining that add up to a sum total
b) too many shims used as a shim and a gasket
c) errors in quantity that cannot be tolerated
d) large differences in part sizes

a) slight errors in machining that add up to a sum total

41


Why would you number a gear in four locations (numbers are stamped on the side of the gear)?
a) to establish a history, which is recorded in maintenance reports
b) to indicate heavy spots when balancing
c) to allow backlash and mesh pattern checks over 360° or at four locations to establish gear and shaft integrity
d) to allow shaft and float checks at four separate locations

c) to allow backlash and mesh pattern checks over 360° or at four locations to establish gear and shaft integrity

42


Damaged gear teeth may have to be hand-worked in order to remove burrs and high spots. This is particularly true if no new gears are available and the gearbox is critical to production. What tool can you use to dress these damaged teeth?
a) Swiss files
b) abrasive files
c) rotary files
d) mounted wheels

b) abrasive files

43


What is used for checking for gear teeth cracks?
a) magnets
b) NDT dye penetrant and developer
c) micro sound devices
d) stress testing


b) NDT dye penetrant and developer

44


Why is residual magnetism dangerous to rebuilt gearboxes?
a) It breaks down EP additives.
b) Magnetism affects the polarization of oil molecules.
c) Magnetism attracts iron particles to wear surfaces.
d) Magnetic plug separation can be neutralized.


c) Magnetism attracts iron particles to wear surfaces.

45


Why are oil dams and scrapers critical to gearboxes?
a) They trap oil during shutdown periods.
b) They wipe oil off rotating gears and channel the lube to the bearings.
c) They stop abrasive contamination from settling out.
d) They promote good gear tooth lubrication.


b) They wipe oil off rotating gears and channel the lube to the bearings.

46


Why should oil pressure-fed lube systems found in gearboxes be checked?
a) Wear in the pump can reduce the flow of lubricant.
b) Vibration of gears and shafts causes pump wear.
c) Piping OD can become contaminated.
d) Pipe fittings can become brittle from vibration.


a) Wear in the pump can reduce the flow of lubricant.

47


Overhauled gearboxes should be fitted with magnetic drain plugs and:
a) dip sticks.
b) oil level plugs.
c) visual oil sight glasses.
d) filler ports.


c) visual oil sight glasses.