Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Gear drives Millwright Mechanics lvl 2 Exams Prep, Exams of Mechanics

Millwright Mechanics Gear drives Millwright Mechanics lvl 2 Exams Prep

Typology: Exams

2024/2025

Available from 06/18/2025

Fortis-In-Re
Fortis-In-Re 🇺🇸

1

(1)

2.3K documents

1 / 14

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
Gear drives Millwright Mechanics lvl 2 Exams Prep
1
/
14
1.
Gears
increase
speed
using
an
Overdrive
unit
2.
Gears
reduce
speed
and
increase
torque
using
a
Reduction
unit
3.
connect shafts by using a gear train Gears
4.
What is the pitch circle of a gear?
Circumference of the
cylinder
5.
What is the pitch line?
Line of contact between 2
cylinders
6.
What
is
the
addendum?
1) amount of gear tooth
1)
the
amount
of
the
gear
tooth
above
the
pitch
circle
above pitch circle
2)
the amount of the gear tooth below the pitch circle
7.
On
a
gear
chart,
where
is
the
addendum
located?
Between
pitch
circle
and
outside
diameter
8.
On a gear chart, where is the circular pitch (CP) locat-
ed?
The distance between two
corresponding points on
adjacent teeth, measured
on the pitch circle
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe

Partial preview of the text

Download Gear drives Millwright Mechanics lvl 2 Exams Prep and more Exams Mechanics in PDF only on Docsity!

Gear drives Millwright Mechanics lvl 2 Exams Prep

  1. Gears increase speed using an Overdrive unit
  2. Gears reduce speed and increase torque using a Reduction unit
  3. connect shafts by using a gear train Gears
  4. What is the pitch circle of a gear? Circumference of the cylinder
  5. What is the pitch line? Line of contact between 2 cylinders
  6. What is the addendum? 1) amount of gear tooth
    1. the amount of the gear tooth above the pitch circle above pitch circle
    2. the amount of the gear tooth below the pitch circle
  7. On a gear chart, where is the addendum located? Between pitch circle and outside diameter
  8. On a gear chart, where is the circular pitch (CP) locat- ed?

The distance between two corresponding points on adjacent teeth, measured on the pitch circle

Gear drives Millwright Mechanics lvl 2 Exams Prep

  1. On a gear chart, where is the Dedendum located? Between pitch circle and root diameter
  2. On a gear chart, where is the clearance (CL) located? It's the gap between working depth and the whole depth
  3. What is the diametral pitch and what is the formula? Total number of teeth on the gear divided by pitch diameter in inches DP = N / PD
  4. What is the pitch diameter? Diameter of pitch circle
  5. Diametral pitch, pressure angle, and tooth profile are integral to proper of gears

Meshing

  1. What is the whole depth? Total height of a tooth OR the total depth of a tooth space

Gear drives Millwright Mechanics lvl 2 Exams Prep

  1. Why are spur gears with 20 degree angles preferred over gears with 14.5 degree angles?
  2. How can you visually identify a spur gear with a 20 degree pressure angle?
  3. How can you visually distinguish a 14.5 degree pres- sure angle spur gear?

Greater strength and wear resistance

Bottom tooth width is larger than the top

When 2 tooth widths look about equal

  1. Involute profile means of the tooth Shape
  2. What happens when 2 meshing gears with the same DP (diametral pitch) and pressure angle but different number of teeth are used together?
    1. utter destruction
    2. tooth wear increases
    3. enhances rolling action of teeth
    4. none of the above

Enhances the rolling ac- tion of the meshing teeth

  1. What is the formula for backlash? 0.030/DP
  2. What is backlash? Amount of play between mating teeth
  3. What are 3 purposes of backlash? 1) allow for heat expan- sion
    1. prevents interference with incoming and outgo- ing teeth
    2. Lubrication escape route
  4. Backlash

Gear drives Millwright Mechanics lvl 2 Exams Prep

Lack of in gears prevents lubricants from escaping and causes extreme noise and wear

  1. Backlash is measured in...? Thousandths of an inch
  2. When lubricants cannot escape from meshing teeth, what kind of pressure is created?
  3. Gears are primarily made from these 3 material groups:
  4. What advantage do steel gears have over other fer- rous types?
  5. What advantages do cast iron gears have over other ferrous types?

Hydraulic. Forces gears apart. No good can come from this

Ferrous metals Non ferrous metals Non metallic materials

When heat treated, they carry the greatest loads and torque

Easy to machine Cheap Wear resistance Run quietly

  1. What is a disadvantage of cast iron gears? Brittle
  2. Stainless steel gears are used in situations where resistance is vital
  3. What are the 2 most common non ferrous metals for gears?
  4. gears are tough and wear resistant, easy to cast and machine

Corrosion

Bronze and aluminum

Bronze

Gear drives Millwright Mechanics lvl 2 Exams Prep

  1. What is the main function of rack and pinion gearing? Converts rotary motion to linear motion and vice ver- sa
  2. What is the standard angle of a helical gear? (Aka the helix angle)
  3. A pair mating helical gears must be of:
    1. same direction of tooth slope
    2. different diametral pitch
    3. opposite direction of tooth slope
    4. different pressure angle

45 degrees

  1. opposite direction of tooth slope (opposite hand)
  1. When parallel shafts are connected by one set of heli- Axial thrust cal gears, what type of force is generated?
  2. How is axial thrust compensated for on helical gears connecting parallel shafts?
  3. To connect crossing shafts, which set up would you use?
    1. pair of mating gears of the opposite hand
    2. 2 gears with the same hand of rotation.
    3. angular bevel gears
    4. bevel gears

Axial thrust bearings

  1. 2 gears with the same hand of rotation
  1. Which gear set up is used to connect shafts that inter- 1) bevel gears sect and usually at right angles?
    1. bevel gears
    2. helical gears with opposite hand rotation
    3. helical gears with same hand of rotation
    4. angular bevel gears

Gear drives Millwright Mechanics lvl 2 Exams Prep

  1. In bevel gears, the smaller one is called the and Pinion and ring

the large gear is called the

  1. Why are bevel gears sold as a matched set? Pitch-cone angles of the meshing gears are related to the shaft angle
  2. In bevel gears, if one has a pitch-cone angle of 90 degrees it's called a

Crown

  1. What is the shape of a crown gear? Disk shape
  2. In bevel gears, if the pitch-cone is greater than 90 degrees, what is the gear called?

Internal bevel

  1. What is the shape of an internal bevel gear? Cup shape
  2. Which gears have curved teeth at a zero angle? Zerol (trademark name)
  3. Which runs the loudest: zerol, straight bevel, or spiral Straight bevel bevel
  4. gears have several teeth meshed at one time and develop axial thrust
  5. gears connect shafts that intersect at other than 90 degrees
    • gears change shaft direction and generate a 1:1 ratio?
  6. gears transmit power between shafts that cross but do not intersect

Spiral bevel

Angular bevel

Mitre

Hypoid

  1. Hyoid and spiral bevel
  1. Non-throated, single throated, and double throated are the on worm gear sets
  2. What are the three contact patterns on worm gear sets?
  3. In this worm gear contact type, the outline of the worm gear teeth curves to match the shape of the worm
    1. non throated
    2. single throated
    3. double throated
  4. In this worm gear contact type, the worm profile is modified to increase contact between worm and worm gear curve
    1. non throated
    2. single throated
    3. double throated

Contact patterns

Non throated Single Throated Double throated

Single throated

Double throated

  1. In this worm gear contact type, teeth on the worm all 1) non throated have the same depth and linear pitch
    1. non throated
    2. single throated
    3. double throated
  2. Which of the 3 worm gear contact types has only 1-2 tooth engagement that leads to early wear and failures?

Non throated

  1. Worm and worm gears create what type of thrust? End
  1. units increase speed which results in torque loss
  2. units consist of a pair of gears in a rigid, strong, movable housing

Overdrive

Reduction

  1. What is the purpose of a reduction unit? Reduce speed and in- crease torque
  2. A single reduction unit has gears and shafts
    1. 2 and 2
    2. 4 and 3
    3. 2 and 3
    4. 4 and 4
  3. A multiple reduction unit has or more gears on or more shafts
    1. 3 and 4
    2. 4 and 6
    3. 6 and 4
    4. 4 and 3
  4. In worm gear reduction units, bearings are needed to allow for loading of gear action

2 and 2

4 and 3

Axial thrust and thrust

  1. What should you do before removing any type of bear- Make damn sure you got ings?
  2. When fitting worm gear reduction units, are needed to get the correct bearing

some replacements avail- able Because, holy shit, that won't be a good time.

Shim packs and preload

  1. Rule of thumb: which order should gears be fitted in reduction units?
1) pinion, intermediate gears, largest 2) intermediate gears, largest, pinion 3) largest, intermediate, pinion 4) any order is fine 
  1. How is correct backlash established in herringbone gears?
  1. largest, intermediate, pinion. =g‹et it?

By centre to centre dis- tance of shafts

  1. Herringbone gears cannot have the adjusted Backlash
  2. Bevel, mitre, and hypoid gears develop Axial thrust
  3. bearings are used where axial thrust is pre- sent

Tapered roller

  1. Planetary gear sets have which 3 drive members? Sun gear Ring gear Carrier aka YOKE ( holds pinion(s) )
  2. In planetary gear sets, which drive member(s) can be either the input or output?
1) sun 2) ring 3) carrier (aka yoke) 4) any of them 
  1. For direct drives; a reducer and power source can be joined in two ways: name 'em

Any of them!

With a flexible coupling, both units need to be Bolted to a strong base ( same base )

  1. Shaft mounted reduction units have a output shaft

A flange mounting, used with combo units

Hollow

  1. Shaft mounted reduction units have a torque arm that Right angle should be as close to a as possible
  2. On shaft mounted reduction units, the drive is at right angles between the output and input shafts

V belt

  1. An indirect drive for reducer and power source can be V belts

joined in which 2 ways

  1. What lubrication method is most common in reduc- tion units?

Chain drives

Splash

  1. For indirect drives where a reducer and power source Separate are joined, the units can be on bases
  2. *mitre gears are bevel gears that have the

number of teeth and pitch

Same