TM-9-2350-311-20-1 Maintenance Manual for Volume 1 M109 Hull Download
Page 1162 of 1275
TM9-2350-311-20-1 F-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 F-4). TABLE F-4 SAE SCREW AND BOLT MARKINGS SCREWS BOLTS SAE grade 2 SAE grade 6 No marking Four radial dashes 90° apart SAE grade 3 Two radial dashes SAE grade 7 180° apart Five radial dashes 72° apart SAE grade 5 Three radial dashes SAE grade 8 120° apart Six radial dashes 60° apart Markings On Hex Locknuts Grade A — no marks Grade A — no mark Grade B — three marks Grade B — letter B Grade C — six marks Grade C — letter C Grade A — no notches Grade B — one notch Grade C — two notches F-5/(F-5 blank)