TM-5-2330-378-14-P

SEMITRAILER, LOWBED: 40 TON CONSTRUCTION EQUIPMENT TRANSPORTER M870 AND M870A1

TECHNICAL MANUAL; OPERATOR'S, UNIT, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST)

JUNE 1999

TM-5-2330-378-14-P - Page 488 of 524

TM5-2330-378-14&P

H-4. TIGHTENINGMETAL 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

3G-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 nutortapped

hole (internal threads of the attaching nut ortapped hole) (internal threads). The mostcommon

thread class for bolts and screws is Class 2.

Table H-4. Thread Classes and Description

EXTERNAL

INTERNAL

INTERNAL

1A

1B

LOOSE

FIT

2A

2B

MEDIUM

FIT

3A

3B

CLOSE FIT

NOMINAL

SIZE

NO.THREADS/INCH

I

I

I

THREAD

SYMBOL7-

I

------

I

THREADCLASS

3/4

10

UNC

2A

NOTE:Unlessfollowedwith-LH(e.g.,314-10UNC-2A-LH),

threadsareright-hand.

LENGTH

(BOLT SHANK)

THICKNESS

GRIP

G

OR HEIGHT

BODYLENGTH

HEI

HT

OFHEAD

I

--T

r

LENGTH

OF NUT

HAL

NMI

NOW

T

DIAMETER

Ono

THREAD

L

THREAD

RU"OUT

LENGTH

I

LENGTH

H-4