These specialized fasteners are used to connect fluid lines to components such as calipers, master cylinders, and fuel systems. Characterized by a hollow bolt body with a hole drilled through its center and a radial hole(s) near the threaded end, they allow fluid to pass through the bolt itself. This configuration enables a secure and leak-proof connection, especially in tight spaces where conventional fittings might be difficult to install. For instance, in a hydraulic braking system, it connects the brake line to the caliper, delivering brake fluid when the brake pedal is depressed.
The utilization of these bolts offers several advantages, including compact design, ease of installation, and reliable sealing. The design ensures minimal fluid restriction while maintaining a robust connection capable of withstanding high pressures. Historically, their adoption stemmed from the need for efficient and reliable fluid transfer in automotive and aerospace applications where space and weight are primary considerations. Their continued use underlines their proven performance and adaptability to diverse engineering requirements.