TM 9--2350--292--20--2
0720 00--4
TORQUE LIMITS -- CONTINUED
0720 00
TIGHTENING METAL FASTENERS -- CONTINUED
Table 3. TORQUE RANGES
STATED RANGE
MOST EFFECTIVE RANGE
0--200 lb--ft
0--600 lb--ft
0--170 lb--ft
15--75 lb--ft
50--150 lb--ft
150--450 lb--ft
44--131 lb--ft
30--60 lb--ft
FASTENER SIZE AND THREAD PATTERN
Threaded fasteners are categorized according to diameter of the fastener shank. Thread styles are divided into broad
groups, the two most common being coarse (Unified CoarsUNC) and fine (Unified FinUNF). These groups are de-
fined by the number of threads per inch on the bolt shanks. In addition, threads are categorized by thread class
(Table 4), which is a measure of the degree of fit between the threads of the bolt or screw (external threads) and the
threads of the attaching nut or tapped hole (internal threads). The most common thread class for bolts and screws is
Class 2.
Table 4. THREAD CLASSES AND DESCRIPTION
EXTERNAL
INTERNAL
FIT
1A
2A
3A
1B
2B
3B
LOOSE FIT
MEDIUM FIT
CLOSE FIT
Thread patterns are designed as follows:
NOMINAL SIZE
NO. THREADS/INCH
THREAD SYMBOL
THREAD CLASS
3/4
10
UNC
2A
NOTE: Unless followed with --LH (e.g. 3/4--1 OUNC--2A--LH), threads are right hand.
HIPH1511
THICKNESS
OR HEIGHT
OF HEAD
LENGTH
(BOLT SHANK)
BODY
LENGTH
NOMINAL
DIAMETER
THREAD
RUNOUT
LENGTH
THREAD
LENGTH
GRIP
LENGTH
HEIGHT
OF NUT