Top Lock Nut Markings

All metal prevailing torque type lock nuts achieve their prevailing torque by altering the shape of the nut in some way most commonly by distorting the threads of the nut which then bites into the mating part when tightened.

Top lock nut markings.

Fasteners commonly have two different markings. Manufacture s identification mark e g x applied to head raised or depressed at option of manufacturer. Nuts coated cadmium shall have a plus sign marked after the grade symbol. A unique manufacturer identification symbol such as letters or an insignia and information about the fastener strength.

A head with no markings is grade 2 one with 3 lines spaced 120 degrees is grade 5 and 6 lines spaced at 60 degree intervals is grade 8. All metal locknuts prevailing torque cone type iso 7042 7720 class 9 cone din 980v. 2 way reversible lock nuts flex type lock nuts stover lock nuts. Full hex nut type din 934.

Top lock distorted thread locknuts class 8. All metal lock nuts the most common design is a nut with a crowned top looks like an upside down wheel nut. Collar type din 934. The above chart should not be considered all inclusive for the fasteners listed the nuts listed are those that are readily available.

Center lock flange type din 6927. The nuts bolts and washers used on the airplane are in accordance with air force navy specifications military specifications and national aircraft standards. Jam center lock iso. Bolt heads and nuts are often marked with numbers letters dashes slashes dots or an assortment of other marks.

Screws are marked on the top of their heads the exceptions being small under about 1 4 slotted and recessed head fasteners where there is insufficient room for head markings. Common names for all metal lock nuts are. Lock nuts typically fall into two categories. Gr8 hex nut type.

The crowned top is crimped to create a prevailing torque feature that increases the nut s resistance to loosening. Cone flange type iso 7044. These metric locknuts have an irregularly shaped thread at the top of the nut that grips the bolt for a stronger hold than nylon insert locknuts. These metric locknuts have an irregularly shaped thread at the top of the nut that grips the bolt for a stronger hold than nylon insert locknuts.

Both markings will be acceptable for a transition period. Medium strength steel top lock distorted thread locknuts grade 5. Such markings differ based on how the fasteners were made. Top lock flange type din 6927.

A 4 9 0 x symbol for identification of grade i e a490 applied to head. This section contains information on the correct usage and identification of bolts flat washers lock wash ers nuts lock nuts fittings and torque data.