The part number **21002-R** generally refers to a specific **Rotary Switch** or a **Power Distribution Module (PDM)** component, depending on the manufacturer. Most commonly, this part is associated with **Cole Hersee (Littelfuse)** or specialized industrial electronic hardware. --- ### 1. Common Specifications (Cole Hersee / Littelfuse) In many industrial contexts, the 21002-R is a heavy-duty rotary switch designed for automotive or marine environments. | Feature | Specification | | :--- | :--- | | **Component Type** | Rotary Lighting/Master Switch | | **Material** | Plated Steel Housing / Brass Terminals | | **Voltage Rating** | 12V - 24V DC | | **Positions** | Usually 3-position (Off - Park/Tail - Headlight) | | **Termination** | Screw Terminals (4-5 terminals) | | **Mounting** | Through-hole (Panel Mount) | ### 2. Electronic Functionality The device acts as a manual interface to manage high-current circuits. Unlike standard toggle switches, the rotary mechanism in the 21002-R is built for durability and high vibration resistance. * **Switching Logic:** It typically utilizes a "Make-Before-Break" or "Break-Before-Make" internal contact arrangement to ensure that lighting circuits do not flicker or surge during position changes. * **Current Handling:** Designed to handle up to 20A–30A at 12V DC without the need for an external relay in simple circuits. ### 3. Alternative Identification If the part is not a mechanical switch, it may refer to: * **RF/Inductor Components:** In some small-signal electronics, "21002" prefixes are used for shielded power inductors or surface-mount (SMD) components where the **-R** suffix denotes **RoHS Compliance** (Restriction of Hazardous Substances). * **Cable Assemblies:** In certain server/IT hardware (like IBM or Dell), this may represent a specific proprietary power cable or sensor lead. --- ### Technical Schematic Representation If you are integrating this into a circuit diagram, the pinout usually follows this logic: ```text [Terminal B] -- (Battery/Power Input) | [Rotary Mechanism] / | \ [Off] [Pos 1] [Pos 2] | | [Parking Lts] [Headlights] ``` ---