An illustrated parts breakdown (IPB) is a publication usually in the form of an OP that describes and illustrates all components used in ordnance equipment. An IPB is broken down into sections that identify component parts by major assemblies, subassemblies, and detailed parts. All illustrations in these publications have figure and index numbers for proper repair part identification. The figure number represents a unit; the index number identifies just one part of that unit. Each unit has an identifying part number and accompanying each part number are the name and description of the part it represents. Part numbers are then cross-referenced to a current NSN to order replacements. The IPB illustrates the assembly of your equipment using expanded drawings. These expanded drawings are very helpful in locating lubrication fittings and other components that often elude a maintenance person.

Some IPBs have a cross-reference section that converts the identifying number to a part number or national stock number (NSN). These cross-References may not have the latest NSN; the appropriate section of the Coordinated Shipboard Allowance List (COSAL) should list all the latest NSNs. An index of IPBs is listed in OP 0.

HYDRAULIC DIAGRAMS

Hydraulic symbols are used throughout the world in design, operation, and maintenance of fluid power systems. A thorough knowledge of hydraulic symbols will enable you to read and understand hydraulic circuit diagrams and other drawings of hydraulic circuits.

Hydraulics today have many and varied applications; therefore, a standardized set of symbols was agreed upon at a joint industrial conference of leaders. This conference recommended a system of designating symbols that some of the commercial manufacturers are presently using. These symbols for fluid power diagrams are listed in USAS Y32.10.

Graphic symbols provide clear-cut circuit information, and well-prepared circuit diagrams show every part of a hydraulic circuit clearly. Symbols are available for most commercial components. Drawings that use symbols will normally also supply a legend for their interpretation. Blueprint Reading and Sketching, NAVEDTRA 12014, and Fluid Power, NAVEDTRA 12964, give some elementary information on the theoretical background of drafting, on how to read drawings of all types, how to sketch, what type of information is found in a title box of drawings and schematics, and additional information on symbols used in electrical, electronic, and pneumatic sketches, schematics, block diagrams, and mechanical drawings.

PARTS NUMBERS

When ordnance parts are identified through the use of the IPB, ordnance drawings, or from part of manufacturer's numbers stamped on the parts, an NSN for each part is required before the parts can be

requisitioned. These NSNs are listed in the COSAL that has across-reference section that converts apart number to an NSN.

The COSAL establishes the shipboard allowance for installed and portable equipment, equipage, and supporting material. Each COSAL is prepared for an individual ship and enables that ship to have a maximum self-supporting capability for an extended period of time.

Ships are issued a separate COSAL for each category of material. The index to all COSALs is issued by the Naval Supply Systems Command. Normally, one copy of the ordnance COSAL is kept by the supply department and one copy by the weapons or combat systems department,

If an NSN for a part cannot be found, the part can be requisitioned by the drawing and piece number and any other identification, such as the equipment's mark and mod, the manufacturer's name, the amperage and voltage rating, the name of electrical parts, and the serial number of the major unit from which the part was removed. Additional information about apart can also be obtained from equipment IPBs.

COMMON MAINTENANCE PROCEDURES

LEARNING OBJECTIVES: Discuss hydraulic and mechanical maintenance procedures, seal replacement, and special tools used on naval gun systems.

Traditionally, some of the most common preventive maintenance procedures have had to be learned by the maintenance person on the job. This is the case with replacing hydraulic seals and making mechanical adjustments. In this section we will provide you with some insight into the performance of these procedures. It maybe helpful to have the maintenance manuals for your system handy to refer to as we go through these procedures. In all cases, you must consider the system maintenance manuals and maintenance requirement cards (MRCs) as your primary source of guidance and information. The information provided here is intended to augment and clarify these manuals.