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Which Type of Skeleton Oil Seal Should You Choose for Hydraulic Equipment?

Hydraulic systems rely on precision, durability, and reliability. Among all the components that keep them running smoothly, the skeleton oil seal (also known as a metal-cased oil seal) plays a vital role. It prevents leakage of hydraulic oil, protects internal parts from contaminants, and ensures consistent performance under demanding operating conditions. But with so many types available, how do you choose the right skeleton oil seal for your hydraulic equipment?

What Is a Skeleton Oil Seal?

A skeleton oil seal is essentially a rubber sealing element reinforced with a metal frame (skeleton). The skeleton provides structural strength and dimensional stability, while the rubber lip maintains a tight seal against the shaft surface. This combination makes it ideal for applications with high pressure, fast shaft rotation, or harsh working environments.
In hydraulic equipment—such as pumps, cylinders, motors, and valves—skeleton oil seals are used to keep lubricants inside while keeping water, dust, and other contaminants outside.
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Types of Skeleton Oil Seals for Hydraulic Equipment

1. Single-Lip Skeleton Oil Seal
Design: One sealing lip in contact with the shaft.
Application: Best for equipment where the main concern is preventing oil leakage under moderate conditions.
Pros: Simple, low-cost, effective for standard hydraulic systems.
Limitations: Less effective against external contaminants.
 

2. Double-Lip Skeleton Oil Seal
Design: One primary sealing lip plus an additional dust lip.
Application: Ideal for hydraulic systems exposed to dusty, wet, or outdoor environments.
Pros: Provides extra protection against contamination, prolongs the life of hydraulic oil.
Limitations: Slightly more friction compared to single-lip seals.

3. Cassette Skeleton Oil Seal
Design: Multi-layer sealing with an integrated dust cover.
Application: Heavy-duty hydraulic machinery like excavators, loaders, and agricultural equipment.
Pros: Excellent resistance to mud, water, and abrasive particles.
Limitations: Higher cost, more complex structure.

4. High-Temperature Skeleton Oil Seal
Design: Uses fluororubber (FKM) or PTFE sealing materials with metal reinforcement.
Application: Hydraulic equipment operating in extreme heat, such as steel mills or power plants.
Pros: Excellent chemical and heat resistance, stable under long-term use.
Limitations: More expensive than standard NBR-based seals.
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Key Factors to Consider When Choosing

Operating Pressure and Speed – Ensure the seal can withstand the system’s maximum hydraulic pressure and shaft speed.
Temperature Range – Match the seal material (NBR, FKM, PTFE) with your working environment.
Contamination Level – If your equipment is exposed to dirt, water, or chemicals, opt for double-lip or cassette types.
Service Life and Maintenance – A longer-lasting skeleton oil seal reduces downtime and maintenance costs.
Compatibility with Hydraulic Oil – Confirm that the seal material is resistant to your system’s oil and additives.
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Why Skeleton Oil Seals Matter in Hydraulic Systems

A failing seal can lead to hydraulic oil leakage, loss of pressure, increased friction, and premature wear of key components. By selecting the right skeleton oil seal, you ensure:

•  Stable system pressure
•  Longer service life of hydraulic components
•  Lower maintenance costs
•  Improved safety and reliability
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Why Choose Parjet as Your Skeleton Oil Seal Manufacturer?

At Parjet, we specialize in high-performance sealing solutions, including skeleton oil seals, PTFE rotary seals, lip seals, and spring-energized seals. As a professional Taiwan seal manufacturer, we are trusted by industries worldwide for our:

•    Advanced Materials – We offer skeleton oil seals made with NBR, FKM, and PTFE to fit different hydraulic environments.
•    Custom Design Capability – Our team can provide tailored solutions based on customer requirements, including different skeleton materials such as SPCD mild steel, SUS304, SUS316, or DIN1.4301 stainless steel.
•    Reliable Quality – With strict international quality standards and in-house CNC machining, we deliver seals with precision and durability.
•    Industry Expertise – From hydraulic equipment to heavy machinery, our seals are engineered to meet the toughest demands.
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Conclusion

The right skeleton oil seal makes a big difference in the efficiency and durability of hydraulic equipment. Single-lip seals are great for standard use, double-lip seals for dusty conditions, cassette seals for heavy-duty applications, and high-temperature seals for extreme environments.
If you are looking for a reliable Taiwan skeleton oil seal manufacturer, Parjet is your trusted partner. Our expertise in sealing technology ensures your hydraulic equipment runs efficiently, reliably, and cost-effectively.
 

Contact Parjet today to learn more about how we can provide the best sealing solution for your hydraulic systems.