Hydraulic Seal Stack Design: How to Build the Perfect Sealing System for Your Cylinder in 2025

hydraulic seal stack

目次

Sealing just one part of your hydraulic cylinder isn’t enough. To prevent leakage, absorb shocks, and reduce downtime—you need a complete seal stack.

A hydraulic seal stack is a strategic combination of rod, piston, buffer, and wiper seals. When built correctly, it ensures your system performs under pressure, lasts longer, and leaks less.

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In this 2025 guide, I’ll walk you through how to build the perfect seal stack for your hydraulic cylinders.

What is a hydraulic seal stack?

A seal stack is a layered arrangement of different seal types in one cylinder—each handling a specific role:

  • ロッドシール to block fluid from exiting
  • ピストンシール to divide pressure chambers
  • バッファシール to absorb shocks and prevent extrusion
  • Wipers to keep contaminants out
  • Guide rings to ensure alignment and prevent side loading

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At Hengoseal, we often combine UNロッドシール, IDU/ODU piston seals、 そして KDAS buffer seals in a single cylinder for optimal sealing.

Which seals should be included in a standard cylinder?

Here’s a typical seal stack layout for a double-acting hydraulic cylinder:

位置 シールタイプ Example Product
Rod Side ロッドシール UN油圧シール
Rod Side バッファシール KDASコンパクトシール or UHS
Rod Side ワイパーシール Custom Dust Seal
Piston Side ピストンシール IDU/ODUシール
Guide Wear Ring FA or PTFE Guide Band

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Depending on the application, you can swap KDAS for V-type seals or use USH buffer seals for higher extrusion resistance.

How do you choose seals based on pressure and stroke?

状態 Recommended Seals
Pressure ≤ 25 MPa UN + IDU + UHS
Pressure 25–40 MPa UN + KDAS + ODU
Pressure ≥ 40 MPa V-type seal + USH buffer
Stroke ≤ 100mm IDU + KDAS
Stroke ≥ 300mm ODU + USH + reinforced wiper

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If your application involves sudden pressure spikes or long-stroke movement, you’ll need additional buffer or guide elements to prevent seal blowout and misalignment.

Need help measuring your groove? Visit our guide on how to measure hydraulic seals accurately.

What materials should you use in a seal stack?

Choosing the right material ensures your seal stack resists wear, heat, and chemical damage.

材料 使用事例
ノンブル Mineral oil systems, -30~100°C
フッ化水素 High-temp or fuel systems, up to 200°C
プエルトリコ Abrasion-resistant, long-stroke systems
PTFE Chemical resistance, low friction

You can combine materials—such as a PTFE piston seal with a PU buffer and FKM rod seal—for optimal performance in multi-fluid systems.

What are the most common sealing failures—and how to avoid them?

  1. Leakage – Caused by undersized seals or incorrect groove.
  2. Extrusion – Happens under high pressure without buffer rings.
  3. Wear – From side loading or dry friction.
  4. 汚染 – When no wiper seal is used.

To avoid these, follow our seal failure prevention guide and always use a complete stack.

結論

A well-designed hydraulic seal stack is the foundation of a leak-free, high-performance cylinder. Pair the right seal types, materials, and dimensions—and your system will thank you.

Get your custom seal stack designed today

📩 mail:[email protected]
📞 WhatsApp:+86 17622979498

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よくある質問

1. What’s the minimum number of seals in a hydraulic stack?
At least 3: rod, piston, and wiper.
2. Can I mix different materials in one seal stack?
Yes—mixing PU, FKM, and PTFE improves versatility.
3. Should buffer seals always be included?
In high-pressure or shock-load systems—yes.
4. How do I know my stack has enough extrusion resistance?
Use backup rings and high-durometer materials like PTFE.
5. Do OEM cylinders follow standard groove sizes?
Often yes, but we recommend measuring or requesting drawings.
6. Can I buy full seal stack kits from Hengoseal?
Yes, we offer size-based or custom kits for all applications.
7. What’s the best stack for excavators?
V-pack buffer + PTFE piston + NBR rod + dust wiper.
8. Can I reuse old seals during maintenance?
No. Always replace seals to prevent premature failure.
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