After fabrication, parts and assembled equipment shall be cleaned of smudges; loose, spattered, or excess solder; weld metal; metal chips and mold release agents; or any other foreign material which might detract from the intended operation, function, or appearance of the equipment.
5.1.2 Threaded parts or devices
Screws, nuts and bolts shall show no evidence of cross threading, mutilation, or detrimental or hazardous burrs, and shall be firmly secured. The length of the screws and bolts installed with nuts shall be such that the exposed portion is a minimum length equivalent to 1.5 thread pitches plus the chamfer. Maximum length shall be limited by the nearest larger standard screw length.
5.1.3 Removable Parts & Mating Connectors
- Electronic equipment shall be furnished with a complete set of installed fuses, lamps, plug-in relays and other parts which are used in the equipment and which are similarly designed for quick removal and replacement.
- Mating cables and connectors required for normal equipment operation shall be provided.
Equipment shall be designed for installation, removal and reinstallation without special tools unless with written approval by Caltrans.
5.1.5 Construction & Mounting
Equipment shall be constructed so that no fixed part shall become loose during transport or during normal maintenance and operations functions.
5.1.6 Fastener Hardware
- Fasteners shall be able to be removed and installed without damage to hardware.
- Fasteners shall remain secure when exposed to equipment operational and environmental stresses.
- Except for those items designed to be affixed with one fastener, parts shall be secured so failure of a single fastener will not free the part completely.
- Friction between mating surfaces shall not be employed as the sole means of preventing fixed parts from rotating or shifting.
- Fasteners shall be selected to minimize the number of standard tools used during maintenance.
All glass used in the equipment, shall be of the shatterproof type and appropriate for the specified environmental condition.
- Unsoldering of wires, wire harnesses, parts or assemblies shall not be required in order to gain access to terminals, soldered connections, mounting screws and the like during routine servicing and maintenance.
- When it is necessary to displace a part in order to check or remove another part, the former part shall be wired and mounted so that it can be moved without being disconnected and without causing circuit detuning or instability.
- Removal of the front panel or any sub-chassis for maintenance purposes shall be accomplished without unsoldering or soldering of connections.
Parts which are identified as replaceable parts shall not be mounted by means of rivets, spot welding, or hard curing compounds. Design shall be such that where plug-in modules or assemblies are used, they can be easily inserted in the proper location when correctly oriented without damage to equipment or parts being engaged.
Accessibility to chassis, assemblies, or parts contained within cabinets, consoles or other enclosures shall be provided from outside the basic equipment through the use of access doors, or by mounting such items on withdrawal slides, swinging doors, through cable extenders and cable retractors, provisions for circuit card extenders which shall allow part or module operation in the open position, or other arrangements to permit adequate access for properly servicing the equipment. Automatic or manually operated locks shall be provided to lock the chassis in the servicing position. When withdrawal slides are used they shall be of guided sectional construction with tracks and rollers. Complete removal and access for servicing of electronic equipment contained within cabinets, consoles or other enclosures shall be provided from either the front, side or rear of the equipment. Guide pins or locating pins, or the equivalent, shall be provided for mechanical alignment during mounting. Access panels and doors shall have means of support.
Equipment shall be designed for optimum accessibility compatible with operating, maintenance, electromagnetic compatibility, and enclosure requirements.
5.3.1 Unavailable Parts
When the equipment design specifies a part that is unavailable, a substitute part which meets the form, fit, and functional characteristics of the specified part may be substituted after written approval of Caltrans is obtained.
5.3.2 Initial Qualification / Reliability Demonstration
Substitute parts with quality/reliability characteristics superior to those specified in the parts list shall not be used in equipment to be subjected to initial qualifications or demonstration tests. In other words, a vendor cannot use one quality of parts and components to pass a test or demonstration, then change to lower quality parts for production items. The use of obsolete parts is not allowed.
5.4.1 Design tolerances
Design tolerances shall permit parts, subassemblies and assemblies to be used in their parent assemblies without regard to the source of supply or manufacturer. Parts, subassemblies and assemblies having the full range of dimensions and characteristics permitted by the specification governing the part, subassembly or assembly shall be usable as replacement items and without departure from the specified performance guidelines of the parent items.
5.4.2 Parts and Materials
When written permission is granted to use a nonstandard part or material because the existing standard part or material is not available, the equipment shall be so designed that the nonstandard part or material and the standard part or material is interchangeable. When the specification for the part or material contains substitutability or suppression information, the design shall permit the substitute or superseding parts or materials to be used interchangeably.
5.5.1 Wiring Identification
- All wiring circuits shall be readily identifiable. Circuits shall be identified by either color, number, letters or symbols.
- All terminal blocks shall have identification (i.e. by numbers/letters or schematic).
- A wiring schematic shall be provided and attached to or stored on the vehicle.
5.5.2 Abbreviations and legends
Abbreviations and legends shall conform to ASME Y14.38M.
5.5.3 ID Plates
Assemblies shall be permanently marked or identified. The ID plate shall be fastened in such a manner as to remain firmly affixed throughout the normal life expectancy of the item to which it is attached
5.5.4 Marking cables, cords and wires
The following methods shall be used to mark cables, cords and wires:
- Molded on the cable or cord.
- Stamped on the cable, cord or wire
- Bands securely attached or captivated
- Adhesive tag or tape that shall withstand the applicable environmental guidelines.
5.5.5 Switches & Controls
Switches and electrical controls shall be marked as to their usage.
Marking adjacent to plugs, jacks and other electrical connectors shall identify the connected circuits to preclude cross connections. The connections to AC electrical parts such as motors, generators and transformer shall include a connection schematic on the part.
5.5.7 Programmable items
Equipment which is software programmable shall indicate the identifying number and revision of the software program which has been loaded into memory. The preferred method is to provide either a local or a remote display which is under the control of the software program.
Last updated 01/14/04