Pressure-reducing valves

Pressure-reducing valves limit pressure in one portion of a circuit without affecting system pressure. With flow ratings up to 300 l/min [80 US gal/min] and pressure ratings up to 350 bar [5,075 psi], they are available in direct-acting or pilot-operated types for pressure reducing/relieving or reducing alone.

Features and benefits

Provide pressure control in systems requiring two or more different pressure settings
Wide range of valves available
All operating parts made of hardened and ground materials for maximum durability and leak protection
Enhanced corrosion protection
Can be supplied with zinc plating and anodized aluminum manifolds for additional corrosion resistance
Direct-acting valves provide fast response and are economical solution for low flow applications such as hydraulic brake or motor shift
Pilot-operated valves provide smooth, stable response for high pressure applications, along with precise pressure control with varying flow rates

Applications

Agriculture
Construction
Cranes and material handling
Forestry
Lawn and turf
Road building

Basic operation

Pressure-reducing valves are normally-open, pressure-limiting devices. They limit one part of a circuit to a pre-determined setting, while allowing the inlet pressure to rise to full system pressure, if necessary. They come in two forms: direct-acting or pilot-operated. Both types have the option of an integrated pressure relief valve, which limits the regulated pressure in the case of external forces.

Direct-acting spool type with relief

The direct-acting pressure reducing valve is normally open from port 2 to 1, with port 3 connected to tank. As the pressure at the regulated port 1 increases to the valve setting, the spool moves back against the spring and restricts the flow between port 2 and 1 to maintain the regulated pressure setting. This limits the pressure in port 1, while pressure in port 2 will continue to rise. If an external force creates excessive pressure in the regulated port 1, the spool will move further back and open port 1 to port 3, working as a relief valve.

Pressure Reducing Direct Acting Spool With Relief Basic Op Drawing

Pilot-operated spool type with relief

The pilot-operated pressure-reducing valve is normally open from port 2 to 1, with port 3 connected to tank. As the pressure on the regulated port 1 increases to the valve setting, the pilot section will open and allow the main spool to shift and restrict flow from port 2 to 1. If the pressure in port 1 continues to rise, the main spool will move further back, blocking the line between port 2 and 1. This limits the pressure in port 1, while pressure in port 2 will continue to rise. If an external force causes the pressure in port 1 to rise above the valve setting, the main spool will shift further and open port 1 to tank port 3, acting as a relief.

Pressure Reducing Pilot Operated Spool With Relief Basic Op Drawing

Direct-acting spool type without relief

The direct-acting pressure-reducing valve without relief is normally open from port 2 to 1, with port 3 connected as a drain port only to tank. As the pressure at the regulated port 1 increases to the valve setting, the spool moves back against the spring and restricts the flow between port 2 and 1 to maintain the regulated pressure setting. This limits the pressure in port 1, while pressure in port 2 will continue to rise.

Pressure Reducing Direct Acting Spool Without Relief Basic Op Drawing

Pilot-operated spool type without relief

The pilot operated pressure reducing valve without relief is normally open from port 2 to 1, with port 3 connected to tank. As the pressure on the regulated port 1 increases to the valve setting, the pilot section will open and allow the main spool to shift and restrict flow from port 2 to 1. If the pressure in port 1 continues to rise, the main spool will move further back, blocking the line between port 2 and 1. This limits the pressure in port 1, while pressure in port 2 will continue to rise.

Pressure Reducing Pilot Operated Spool Without Relief Basic Op Drawing

Typical application diagrams

Pressure Reducing Valves App Diag

Pressure-reducing valve comparison

Characteristic/type	Direct-acting reducing	Direct acting reducing/relieving	Pilot-operated reducing	Pilot-operated reducing/relieving
Dirt tolerant	-	-	-	-
Fast acting	+	+	-	-
Flow	-	-	+	+
Pressure	-	-	+	+
Stable	-	-	+	+
Relative Price [1 lowest]	1	1	2	2