Module - Gearing Installation & Maintenance

Question 1

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

Answer 1

American Gear Manufacturers Association

Question 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?

Answer 2

isolate and lock out the machine

Question 3

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

Answer 3

Damage from heat may occur.

Question 4

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

Answer 4

Safety guards should never be removed while units are running.

Question 5

What are two common methods of lubricating open gear sets?

Answer 5

by drop and force-feed systems

Question 6

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

Answer 6

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

Question 7

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

Answer 7

The gears give off a loud whining sound.

Question 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?

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

by keys and set screws

Question 11

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

Answer 11

to prevent gearbox rotation

Question 12

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

Answer 12

spring type torque arms

Question 13

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

Answer 13

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

Question 14

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

Answer 14

Change the motor drive sheave or reducer input sheave size

Question 15

Why are match marks placed on gearboxes?

Answer 15

for ease of reassembly

Question 16

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

Answer 16

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

Question 17

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

Answer 17

You may damage or break the cover.

Question 18

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

Answer 18

Inspection can reveal problems, such as contamination.

Question 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.

Answer 19

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

Question 20

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

Answer 20

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

Question 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.

Answer 21

d) be replaced with new bearings.

Question 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.

Answer 22

c) Use a vernier gear tooth measuring tool.

Question 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.

Answer 23

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

Question 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.

Answer 24

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

Question 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.

Answer 25

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

Question 26

Pulled-up female threads in the lower split joint surface can be removed by:

a) grinding.
b) drilling.
c) countersinking.
d) reaming.

Answer 26

c) countersinking.

Question 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

Answer 27

d) arc clearance between mounted, mating gears

Question 28

Tooth wear on a worm wheel causes:

a) more heat to be generated.
b) more backlash.
c) less backlash.
d) zero backlash.

Answer 28

b) more backlash.

Question 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.

Answer 29

c) a minimum value.

Question 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.

Answer 30

b) at the pitch line.

Question 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.

Answer 31

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

Question 32

Excess backlash can be an indicator that the gear teeth are:

a) wearing.
b) pitting.
c) scoring.
d) flaking.

Answer 32

a) wearing.

Question 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.

Answer 33

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

Question 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

Answer 34

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

Question 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.

Answer 35

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

Question 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.

Answer 36

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

Question 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

Answer 37

a) feeler gauges

Question 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.

Answer 38

b) Mesh patterns allow oil full film lubrication.

Question 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.

Answer 39

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

Question 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

Answer 40

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

Question 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

Answer 41

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

Question 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

Answer 42

b) abrasive files

Question 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

Answer 43

b) NDT dye penetrant and developer

Question 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.

Answer 44

c) Magnetism attracts iron particles to wear surfaces.

Question 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.

Answer 45

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

Question 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.

Answer 46

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

Question 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.

Answer 47

c) visual oil sight glasses.