Applies to establishments engaged in the manufacture, assembly, and repair of heavy equipment. Machinery and equipment subject to this classification are usually made of steel and steel/iron castings and include, but are not limited to, bulldozers, dump trucks, graders, skidders, forklifts and logging towers. The component parts may weigh several hundred to thousands of pounds. Overhead cranes are commonly used in the assembly process. Machinery used in the manufacturing, assembly, and repair includes, but is not limited to, boring mills, lathes, iron workers, welders/cutters, cut saws, and drills. Some establishments use CNC (computer numeric controlled) machinery; however, most establishments in this classification primarily use manual machinery and conventional welders/cutters. Other common operations covered by this classification include paint, welding, and electronic assembly areas. This classification also includes establishments that repair, recoat or resurface press rollers such as, but not limited to, the type rollers used by printing and paper making mills. Operations include repairing the interior shafts of the rollers, then grinding fiberglass or ceramic finishes until they are smooth. For rubber-coated surfaces, they remove the old rubber from the metal surface, sandblast the roller, then recoat it with new rubber. Most establishments that recoat the surface with rubber will mix and extrude their own rubber which is included in this classification when performed by employees of employers subject to this classification.

This classification excludes the manufacture of nonpassenger type vehicles such as semi-trucks which are to be reported in classification 3605; auto or passenger vehicle manufacturing which is to be reported in 3402. Semi-truck repair and service centers are to be reported separately in classification 6409.

Special note: Field work as well as shop work is contemplated as an integral part of this classification. A vehicle may be equipped with welding equipment and other tools used for field repair. The broken part may be replaced in the field or returned to the shop, repaired if feasible, or a new part is ordered. The part is then loaded onto the field vehicle taken to the job site and reconnected. Some establishments perform this type of field work almost exclusively.

Applies to establishments engaged in the manufacture or repair of heavy arms including large munitions. This classification applies to all types of guns 20 MM and larger including, but not limited to, aircraft guns, tank guns, naval guns, torpedoes and aircraft gun turrets.

Special note: Field work as well as shop work is contemplated as an integral part of this classification. A vehicle may be equipped with welding equipment and other tools used for field repair. The broken part may be replaced in the field or returned to the shop, repaired if feasible, or a new part is ordered. The part is then loaded onto the field vehicle taken to the job site and reconnected. Some establishments perform this type of field work almost exclusively.