TM 9-2350-256-20
TABLE F-3. TORQUE RANGES.
Stated Range
Most Effective Range
0-200 pound-inches (lb-in.) (0-23 N m)
50-150 lb-in. (6-17 N m)
15-75 lb-ft (20-102 N m)
30-60 lb-ft (41-81 N m)
0-175 lb-ft (0-237 N m)
44-131 lb-ft (60-178 N m)
0-600 lb-ft (0-813 N m)
150-450 lb-ft (203-610 N m)
F-4
FASTENER SIZE AND THREAD PATTERN
Threaded fasteners are categorized according to the dia. of the fastener shank. Thread styles are divided into broad
groups, the two most common being coarse (Unified Coarse [UNC] ) and fine (Unified Fine [UNF] ). These groups are
defined by the number of threads per 1 in. (25.4 mm) on the bolt shank. In addition, threads are categorized by thread
class (see Table F-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 F4. THREAD CLASSES AND DESCRIPTION.
External
Internal
Fit
1A
1B
Loose
2A
2B
Medium
3A
3B
Close
Thread patterns are designed as follows:
NOTE
Unless followed with-LH (e.g., 3/4-10-UNC-2A-LH), threads are right-hand.
F-5
