Overview
General
WM318 - Parking Brake Control Valve
The WM-325 panel-mounted valve is used as a parking brake control in pre-FMVSS-121 air brake systems in both o-n and off-highway applications. They are normally-closed, three-way valves with pull-to-open, push-to-close knob action. A minimum supply pressure of 35 PSI is required before the WM-325 can be manually operated. As long as the pressure at the WM-325’s inlet exceeds 35 PSI and the valve is actuated, an integral check valve maintains outlet pressure at peak supply levels.
If inlet pressure falls below 35 PSI, the WM-325 parking brake control valve automatically deactivates and exhausts downstream pressure to apply the spring breaks.
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