6.5 Flashcards
what are the 5 different classes of fit
class 1- loose fit
class 2- free fit
class 3- medium fit
class 4- close fit
class 5- tight fit
what class of fit are most aircraft screws
class 2
what class of fit are most aircraft bolts
class 3
what is the definition of a bolt
tightened with a nut
what can be used to tell how many threads per inch
a thread pitch gauge
what is the difference between right and left hand threads
right hand threads are cut clockwise and left hand are cut counter clockwise
what is the crest of a thread
the prominent point of the thread
what is the root of a thread
the lowest point of the thread
what is the flank of a thread
the angle from root to crest
what is the major diameter of a thread
on male thread its crest to crest and on female thread its root to root
what is the minor diameter of a thread
on a male thread its root to root and on female thread its crest to crest
what is the pitch of a thread
the distance between 2 of the same point eg crest to crest
what is the lead of a thread
the distance a screw moves for one complete rotation
what are the negatives of using multiple threads
less holding power and less force produced when tightened
what are the characteristics of British standard whitworth thread forms
55° thread angle, coarse thread used for general purposes
what are the characteristics of British standard fine thread forms
55° thread angle, fine threads mainly used in high vibration areas
what are the characteristics of british association
47.5° thread angle used on very small electrical parts under 1/4 inch diameter
what are the characteristics of american national thread forms
60° thread angle with flat crests and roots
what are the characteristics of unified thread forms
incorporates both american and British features 60° thread angle
what is the difference between coarse and fine threads
coarse threads have a lot more distance between each thread whereas fine has a lot less
what are the 3 other types of thread profiles
square, ACME, buttress
what is the definition of a screw
tightened into a threaded hole
what is the diameter and length measured in for Airforce Navy
length in 1/8 inch and diameter in 1/16 inch
what does the letter A signify in Airforce Navy
the absence of a split pin hole