A pressure relief valve sets the ceiling for a hydraulic circuit. It stays closed while system pressure is below its setting, then opens and diverts flow back to tank so the pump, hoses and actuators never see more than the machine was designed for. Every power unit needs at least one, and most machines also carry secondary relief valves to protect individual functions.
Direct-acting or pilot-operated? Direct-acting valves such as the Rexroth DBD family hold a poppet shut against a spring. They are simple, fast to respond, tolerant of contamination and available for very high settings, but the pressure they hold rises noticeably as flow through them increases. Pilot-operated valves — DB, the solenoid-vented DBW, and the sandwich-plate ZDB / Z2DB — use a small pilot stage to control a large main stage, which gives a much flatter pressure-versus-flow characteristic at high flow and allows the circuit to be unloaded electrically. Screw-in cartridge versions drop straight into a manifold block.
What we need to quote: the type code or material number if you have it; otherwise the pressure range and adjustment type (screw, handwheel or lockable), the nominal size and mounting style (threaded, subplate to ISO 4401, sandwich plate or cartridge), the maximum flow through the valve, and whether a solenoid vent is required.
Related categories: Pressure Reducing Valve · Pressure Sequence & Cut-off Valve · Flow Control Valve · Logic / Cartridge Valve · Directional Control Valve.
Twin Hydraulics Engineering supplies Bosch Rexroth hydraulic valves throughout Malaysia. Send us a type code or material number and we will quote — see also our guide to hydraulic pressure valves.
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