Valve that keeps the (lower) outlet pressure (secondary pressure) p2 constant even with changing inlet pressure (primary pressure) p1. This action is achieved by a valve cone, held open by a spring, that gradually closes as the secondary pressure rises and at the end only replaces the leakage losses QL in the secondary area.
Pressure-reducing valve with secondary pressure limitation (three-way pressure-reducing valve)
Pressure-reducing valve with a relief feature that prevents the pressure on the secondary side increasing above the set value, e.g. due to an excessive load on the output element, i.e. the valve acts from p1 to p2 as a pressure-reducing valve and from p2 to p1 as a pressure-limiting valve.
Pressure-reducing valves can be directly or pilot-controlled.
 Pilot-controlled 2-way pressure-reducing valve |  Pilot-controlled 3-way pressure-reducing valve |
In addition to the spool valves shown, there are also pressure-reducing valves that are designed as a leakage-free Seated valve.