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 489 of 524
TIVI5-2330-378-14&P
H-6.
FASTENERGRADE.
In additionto beingclassifiedbythreadtype,threadfastenersare alsoclassifiedby material. The mostfamiliar
fastener classification system is the SAE grading system (Table H-5).
Table H-5. SAE Screw and Bolt Markings
SCREWS
BOLTS
SAE GRADE 2
SAE GRADE 6
NO MARKING
4 RADIAL DASHES
900 APART
SAE GRADE 3
2 RADIAL DASHES
SAE GRADE 7
1800 APART
5 RADIAL DASHES
720 APART
SAE GRADE 5
3 RADIAL DASHES
SAE GRADE 8
1200 APART
6 RADIAL DASHES
600 APART
Markings on Hex Locknuts
GRADE A - No Marks
GRADE A - No Marks
GRADE B - 3 Marks
GRADE B - Letter B
GRADE C - 6 Marks
GRADE C - Letter C
GRADE A - No Notches
GRADE B - One Notch
GRADE C - Two Notches
H-5/(H-6 blank)
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