TM-9-2350-311-34-2

CAB, ARMAMENT, SIGHTING AND FIRE CONTROL, ELEVATING AND TRAVERSING SYSTEMS AND ASSOCIATED COMPONENTS HOWITZER, MEDIUM, SELF-PROPELLED, 155MM

TECHNICAL MANUAL; DIRECT AND GENERAL SUPPORT MAINTENANCE MANUAL

SEPTEMBER 1994

TM-9-2350-311-34-2 - Page 524 of 552

TM 9-2350-311-34-2

D-5 FASTENER GRADE

In addition to being classified by thread type, threaded fasteners are also classified by material. The most familiar fastener

classification system is the SAE grading system (Table D-4).

Table D-4 SAE SCREW AND BOLT MARKINGS

SCREWS

BOLTS

SAE grade 2

SAE grade 6

No markings

Four radial dashes

90° apart

SAE grade 3

SAE grade 7

Two radial dashes

Five radial dashes

180° apart

72° apart

SAE grade 5

SAE grade 8

Three radial dashes

Six radial dashes

120° apart

60° apart

MARKINGS ON HEX LOCKNUTS

Grade A - no marks

Grade B - three marks

Grade C - six marks

Grade A - no marks

Grade B - letter B

Grade C - letter C

Grade A - no notches

Grade B - one notch

Grade C - two notches

D-6