| FASTENER LENGTH | 1.154 INCHES NOMINAL |
| HARDNESS RATING | 30.0 ROCKWELL C MINIMUM AND 40.0 ROCKWELL C MAXIMUM OVERALL |
| HARDNESS RATING | 40.0 ROCKWELL C MINIMUM AND 50.0 ROCKWELL C MAXIMUM PRIMARY WASHER |
| HEAD LENGTH | 0.545 INCHES MINIMUM AND 0.577 INCHES MAXIMUM |
| HEAD HEIGHT | 0.208 INCHES MINIMUM AND 0.230 INCHES MAXIMUM |
| HEAD STYLE | HEXAGON |
| INTERNAL DRIVE STYLE | W/O INTERNAL DRIVE |
| MATERIAL | STEEL OVERALL |
| MATERIAL | STEEL PRIMARY WASHER |
| III PART NAME ASSIGNED BY CONTROLLING AGENCY | SCREW, SEMS 5/16 - 18 X 1 1/4 |
| PRIMARY WASHER MATERIAL THICKNESS | 0.090 INCHES MINIMUM AND 0.100 INCHES MAXIMUM |
| PRIMARY WASHER OUTSIDE DIAMETER | 0.873 INCHES MINIMUM AND 0.879 INCHES MAXIMUM |
| PRIMARY WASHER STYLE | SPRING TENSION |
| PROPRIETARY CHARACTERISTICS | PACS |
| MINIMUM TENSILE STRENGTH | 105000 POUNDS PER SQUARE INCH |
| NOMINAL THREAD DIAMETER | 0.312 INCHES |
| SPECIAL FEATURES | SCREW MATERIAL IS LOW OR MEDIUM CARBON STEEL; CONICAL WASHER IS STEEL 1050 - 1065 |
| WASHER QUANTITY | 1 |
| WIDTH BETWEEN FLATS | 0.489 INCHES MINIMUM AND 0.511 INCHES MAXIMUM |
| SURFACE TREATMENT DOCUMENT AND CLASSIFICATION | NAVISTAR MATL SPEC G-1, CLASS 3-2 MFR REF SINGLE TREATMENT RESPONSE OVERALL |
| SURFACE TREATMENT | PHOSPHATE OVERALL |
| THREAD CLASS | 2A |
| THREAD DIRECTION | RIGHT-HAND |
| THREAD LENGTH | 1.250 INCHES NOMINAL |
| THREAD QUANTITY PER INCH | 18 |
| THREAD SERIES DESIGNATOR | UNC |