Assignment - Gears & Variable Speed Drives Flashcards Preview

Millwright 2nd Block > Assignment - Gears & Variable Speed Drives > Flashcards

Flashcards in Assignment - Gears & Variable Speed Drives Deck (19):
1


What are the two types of gear drives?


a) open gear drives
b) enclosed gear drives

2


Two gears meshed together with different number of teeth. The gear with the lower number of teeth is called the _____ gear.


pinion

3


Is there a mechanical advantage in a direct drive gear box?


No - direct drive is when the input speed of the gearbox is the same as the output speed. These drives are used for transfer of power with no increase or decrease of speed or torque.

4


In a speed increaser gear box, the drive gear is bigger than the driven gear.
a) true
b) false


a) true

5

What is the minimum number of shafts and gears needed to be called a compound gear train?


3 shafts
4 gears

6


What three things are necessary for gears to mesh?


- same diametral pitch
- same pressure angle
- same helix angle

7


What is an overhung gear?


An overhung gear has a bearings support on only one side.

8


The number of teeth on a gear divided by the pitch diameter will give you.....


DP - Diametral Pitch.

9


A gear set with a pressure angle of 20 degrees is stronger than a gear set with a pressure angle of 14.5 degrees.
a) true
b) false


a) true

10


What are the 3 basic shaft arrangements?


- Parallel
- Intersecting
- Cross over at 90 degrees

11


What are three basic spur gear arrangements? Which one has the two shafts rotate in the same direction?

- External
- Internal
- Rack & Pinion

Internal arrangement has two shafts rotating in the same direction.

12


What is the ratio of mitre gears?


1:1

13


What are two advantages to using double helical gear drives?


The advantage of using double helical gears is that the axial thrust is cancelled out by the opposite row of teeth. These gears are very good for heavy loads and high speeds.

14


What are 3 types of bevel gear sets?


- straight bevel
- spiral bevel
- zerol bevel

15


What worm and wheel arrangement gives the maximum tooth contact?


- double throated gear set

16


Which set of bevel gears have no axial thrust?


- zerol bevel gears

17


The worm is always the _____ member.


input

18


Define "Lead"


Worm lead is the distance by which one tooth on the worm advances in one turn. This is determined by the number of starts on the worm.

19


If the worm wheel has 24 teeth on it and the worm has 3 starts, what is the ratio of the gear box?


8:1