In hydraulic systems, piston seals play a critical role in maintaining pressure efficiency, motion control, and service life. Among various seal profiles, the SPGW piston seal is widely specified in industrial hydraulic cylinders due to its balanced sealing performance, wear resistance, and stability under bidirectional pressure.

What Is an SPGW Piston Seal?

An SPGW piston seal is a double-acting hydraulic piston sealing system that typically consists of three functional elements:

A primary sealing ring (usually elastomer or polyurethane)

Two thermoplastic backup / guide rings on both sides

This structure allows the seal to maintain tight sealing performance under pressure from either direction while preventing extrusion into the clearance gap. The SPGW piston seal is commonly installed in the piston groove of hydraulic cylinders where reciprocating motion and high pressure are present.

How Does an SPGW Piston Seal Work?

The working principle of an SPGW piston seal is based on pressure-activated sealing combined with mechanical support.

When hydraulic pressure is applied, the sealing ring deforms slightly and presses against the cylinder bore, creating a reliable fluid barrier. At the same time, the backup rings limit deformation, control friction, and protect the seal from extrusion—especially under high pressure or large extrusion gaps.

Key advantages include:

1. Low friction coefficient
2. Increase in extrusion gaps to a certain extent
3. Excellent extrusion resistance even during pressure peaks
4. Excellent abrasion resistance

Why Are SPGW Piston Seals Used in Double-Acting Hydraulic Cylinders?

SPGW piston seals are especially suitable for double-acting hydraulic cylinders because they maintain consistent sealing performance regardless of pressure direction.

These characteristics make the SPGW piston seal a common choice in industrial machinery, mobile hydraulics, presses, and heavy-duty equipment.

Typical Materials Used in SPGW Piston Seals

Material selection directly affects sealing performance and durability. Common material combinations for SPGW piston seals include:

Rubber Ring: NBR/FKM

Back-up Ring: POM

PTFE Band: Bronze filled PTFE

These materials provide a balance between elasticity, chemical resistance, wear performance, and temperature stability—allowing the SPGW piston seal to operate reliably in a wide range of hydraulic fluids and operating conditions.

When Should You Choose an SPGW Piston Seal?

An SPGW piston seal is a strong choice when:

The cylinder operates under bidirectional pressure

High sealing reliability is required over long service cycles

Extrusion risk exists due to pressure or clearance

Consistent friction and motion control are important

The SPGW piston seal is not a generic hydraulic seal—it is a purpose-designed piston sealing system engineered for stability, wear resistance, and long-term performance in double-acting hydraulic cylinders. Understanding its structure and function helps ensure correct selection, reduced downtime, and improved system efficiency.