CAT 523-8425 RING SEA-SEM

CAT 523-8425 SEM is a Caterpillar rotary lip seal for shafts, suitable for sealing rotary shafts in hydraulic pumps, gearboxes, final drives, etc., to prevent oil leakage and impurity intrusion. The following is structured technical and application information:

Core Technical Parameters

Item Details
Basic Attributes
Model 523-8425 SEM, Type: Double-lip rotary shaft seal, Material: Nitrile rubber (NBR) + steel skeleton, PTFE wear-resistant coating, Weight: Approximately 0.15 kg, Suitable Temperature: -30℃ to +120℃, Sealing Medium: Hydraulic oil, gear oil, engine oil (Cat)

Key Dimensions
Inner Diameter: 65 mm, Outer Diameter: 90 mm, Thickness: 12 mm, Lip Diameter: 65.2 mm, Spring Diameter: 1.2 mm, Steel Skeleton Thickness: 1.0 mm, Lip Hardness: 70±5 Shore A, Coaxiality: ≤0.02 mm, Surface Roughness: Ra≤0.8 μm

Suitable Models and Locations Compatible with the hydraulic pump drive shaft of Cat 320D/323D excavators, the output shaft of the gearbox of 950H loaders, and the final drive input shaft of D6N bulldozers. One unit per shaft, used for dynamic sealing of rotating shafts to prevent oil leakage and the ingress of dust and moisture.

Performance Parameters: Maximum linear velocity 10 m/s, maximum sealing pressure 0.3 MPa, oil resistance conforms to ISO 1817 standard, compression set ≤20% (100℃×22h), tensile strength ≥15 MPa, elongation at break ≥300%, wear resistance conforms to ASTM D4060 standard.

Structural and Performance Advantages:

Reliable Sealing: Double-lip structure + built-in spring, the lip fits tightly with the shaft, PTFE coating reduces the coefficient of friction, reduces lip wear, and extends seal life; NBR material is oil-resistant and aging-resistant, suitable for common media in construction machinery.

Comprehensive Protection: Dust-proof lip blocks external impurities, main lip seals oil, double protection avoids component damage caused by seal failure, reducing maintenance costs. Easy Installation: The steel frame provides excellent support, preventing deformation during installation. It fits standard sealing grooves, requiring no special tools and improving maintenance efficiency.

High Compatibility: Precisely matches original Cat shafts and sealing grooves, adapting to various operating conditions. High versatility reduces spare parts inventory.

Installation and Maintenance Points: Before installation, clean the shaft surface and sealing groove to remove burrs and oil stains. Check the shaft for scratches and corrosion. Use a dedicated installation tool or socket to press in, avoiding lip flange flipping or spring detachment. After installation, check that the sealing ring fits tightly with the sealing groove.

Maintenance Cycle: Check the sealing ring every 2000 hours. If leakage, lip wear, or spring failure occurs, replace immediately. Avoid damage to the shaft surface that could lead to abnormal lip wear.

Fault Prevention: Apply a small amount of grease to the lip surface during installation to reduce initial friction. Avoid excessive radial runout of the shaft to prevent uneven force on the lip, which could affect the sealing effect.