The Chelsea 378414 Pressure Protection Valve is an essential component in heavy-duty truck air brake systems. It safeguards against total system depressurization by maintaining a minimum holdback of 65–75 PSI when a drop occurs. Redesigned with a direct ¼″ NPT inlet and ⅛″ NPT outlet, this valve simplifies installation by eliminating the need for adapter bushings—reducing leak points and downtime. Built with robust aluminum construction and precision internal sealing, it delivers long-lasting performance across challenging vocational and highway applications. Fits Chelsea OEM spec and offers aftermarket compatibility with Spicer, World American, Newstar, and more. Ideal for PTO applications, air-shifter systems, and hydraulic circuits. Installation is straightforward and requires no further adaptors. Specification Details Inlet Size: ¼″ NPT Outlet Size: ⅛″ NPT Holdback Pressure: 65–75 PSI Construction: Globe valve, aluminum housing Valve Type: Pressure protection valve OEM Part Number: 378414 Cross-References: Spicer 118181/378414, WA9054107, S‑C088 Package Quantity: 1 unit California Prop 65: Applies