The **2HT1-R** refers to a specific series of high-temperature, hermetically sealed toggle switches manufactured by **Honeywell** (part of the MICRO SWITCH™ HT series). These components are designed for extreme environments where standard switches would fail. --- ### 1. Key Technical Specifications The "R" suffix typically denotes a specific lead wire configuration or a RoHS compliance variant, but the core mechanics remain consistent with the 2HT1 series. | Feature | Specification | | :--- | :--- | | **Switch Type** | Toggle Switch | | **Circuitry** | DPST (Double Pole Single Throw) | | **Operating Temperature** | -54°C to +538°C (-65°F to +1000°F) | | **Housing Material** | Stainless Steel / Ceramic | | **Sealing** | Hermetically Sealed (Glass-to-Metal) | | **Actuator** | Standard Lever | --- ### 2. Internal Construction The 2HT1-R is built using specialized materials to survive temperatures that would melt plastic or desolder internal connections. * **Hermetic Seal:** The internal switching mechanism is encased in a ceramic-to-metal or glass-to-metal seal. This prevents gas, moisture, or contaminants from entering the chamber, which is vital for high-altitude aerospace applications. * **Contact Material:** Uses specialized heat-resistant alloys to maintain conductivity and prevent "welding" of contacts under high thermal stress. * **Insulation:** Instead of plastic or polymer insulation, these parts utilize ceramic blocks to separate the electrical poles. --- ### 3. Pinout and Circuitry The **2HT1** designates a Double Pole configuration. In a typical DPST setup: ```text [Internal View] Term 1 (Input) ----/ ---- Term 2 (Output) [Pole A] Term 3 (Input) ----/ ---- Term 4 (Output) [Pole B] ``` --- ### 4. Common Applications Due to its high cost and specialized nature, the 2HT1-R is rarely found in consumer electronics. It is primarily used in: 1. **Aerospace:** Engine compartment controls and landing gear sensors. 2. **Industrial Furnaces:** Manual overrides for high-heat processing equipment. 3. **Power Plants:** Monitoring and control systems near boilers or turbines. 4. **Oil & Gas:** Downhole tools or refinery equipment exposed to extreme heat. --- ### 5. Termination Styles The 2HT1-R version often features **Leaded Terminals** rather than screw terminals. This allows the switch to be integrated into a wire harness using high-temperature brazing or specialized crimping, as standard lead-based solder would melt at the switch's operating limit.