FASTENER SIZE AND THREAD PATTERN - TM-9-2330-202-14-P0385

TM 9-2330-202-14&P

H-4.

TIGHTENING METAL FASTENERS (continued).

Table H-3. Torque Ranges

STATED RANGE

MOST EFFECTIVE RANGE

0-600 ft-lb

150-450 ft-lb

0-170 ft-lb

44-131 ft-lb

15-75 ft-lb

30-60 ft-lb

H-5.

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 Coarse-UNC) and fine (Unified Fine-UNF). These groups are

defined by the number of threads per Inch on the bolt shanks. In addition, threads are categorized by thread class

(Table H-4), which is a measure of the degree between threads of bolt or screw (external threads) and threads of the

attaching nut or tapped hole (internal threads of the attaching nut or tapped hole) (internal threads). The most common

thread class for bolts and screws is Class 2.

Table H-4. Thread Classes and Description

EXTERNAL

INTERNAL

LOOSE FIT

MEDIUM FIT

CLOSE FIT

H-4