Here’s a clear description of the Bosch FD4 Disc Duty Horn 24V Horn Set (often labelled Bosch Compact Disc Horn Set (Steel), 24V (FD4)), a common aftermarket horn for vehicles with 24-volt electrical systems:
Product Overview
• Type: Electric disc-type vehicle horn set
• Model/Series: FD4 (Disc Duty)
• Voltage: 24 V — suited for trucks, buses, commercial vehicles, heavy equipment, and other 24 V electrical systems
• Construction: Durable steel body designed for long service life and resistance to environmental exposure like rust and impacts
Key Features
• Compact disc design: Sounds loud and clear — disc horns are engineered for strong resonance and effective sound projection.
• Loudness: Typical FD4 24 V horns produce around ~110 dB of sound at close range — a powerful warning tone for traffic safety
• Frequency: FD4 horns are available in tones around 335 Hz or 420 Hz depending on specific part configuration (often paired as a set with high and low tones)
• Mounting & Connectors: Simple bracket and electrical connections — usually 2-terminal electric connection for easy installation.
• Heavy-duty use: Built to handle frequent operation in demanding environments (commercial vehicles, industrial use).
• OEM quality: As part of Bosch’s automotive aftermarket range, these are intended to match original equipment durability and performance.
Typical Usage
This 24 V horn set is commonly used as a replacement or upgrade for vehicle horns where louder and more reliable signaling is desired — especially for large vehicles operating in busy traffic or work zones. It’s more powerful and rugged than many standard 12 V horns.
