Professional O-Ring and Oil Seal Manufacturer, Sealing Solution Supplier Since 2008.
URB Polyurethane Seal Two-Piece U Seal with NBR O-Ring Hydraulic Reciprocating Sealing Ring
Category：URB Seal
Temperature: AU Polyester PU: -30℃ ~ +120℃；EU Polyether PU: -50℃ ~ +100℃ (standard grade -35℃~+100℃)
Material: PU+NBR
Color: Green
Hardness: PU: 95 Shore A；NBR energizer:70‑90 Shore A
Product description:
URB seal is a two‑piece U‑shaped composite reciprocating seal, including URB‑R rod seal for piston rod and URB‑P piston seal for cylinder bore. It adopts asymmetric PU U‑shaped main seal lip with built‑in oil storage groove for self‑lubrication, matched with NBR O‑ring energizer to offer continuous preload, compensate wear and improve low‑pressure sealing performance.
Temperature: AU Polyester PU: -30℃ ~ +120℃；EU Polyether PU: -50℃ ~ +100℃ (standard grade -35℃~+100℃)
Material: PU+NBR
Color: Green
Hardness: PU: 95 Shore A；NBR energizer:70‑90 Shore A
Product description:
URB seal is a two‑piece U‑shaped composite reciprocating seal, including URB‑R rod seal for piston rod and URB‑P piston seal for cylinder bore. It adopts asymmetric PU U‑shaped main seal lip with built‑in oil storage groove for self‑lubrication, matched with NBR O‑ring energizer to offer continuous preload, compensate wear and improve low‑pressure sealing performance.
5.0
design customization
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1. Product Overview
URB seal is a two-piece U-shaped composite reciprocating seal, composed of polyurethane(PU) main sealing body and NBR O-ring energizer. Available for piston rod and piston sealing.
With excellent wear resistance, low friction and high anti-extrusion performance, it is widely used in medium & high pressure hydraulic cylinder systems. Standard material is polyester AU PU; polyether EU PU for hydrolysis-resistant working conditions.
2. Product Structure Introduction
URB Standard Cross-section Structure
URB seal consists of PU U-shaped main seal + NBR O-Ring
- PU U-shaped main lip: Asymmetric design. Thin & sharp working lip for self-sealing under low pressure; thick reinforced root to resist extrusion. Built-in oil storage groove for self-lubrication.
- NBR O-ring energizer: Installed at the back of PU seal. Provides lasting preload force, compensates seal wear and improves low-pressure sealing performance.
Two types for selection:
- URB-R: Rod seal (for piston rod)
- URB-P: Piston seal (for cylinder bore）
3. Technical Specification
| Item | Standard Parameter | Remarks |
|---|---|---|
| Material | Main body: PU(AU/EU 90~95 Shore A); Energizer: NBR 70~80 Shore A | Custom hardness available |
| Working Pressure | 0~40MPa, Max 50MPa(modified PU) | Over 40MPa suggest back-up ring |
| Temperature Range | AU Polyester PU: -30℃ ~ +120℃ EU Polyether PU: -50℃ ~ +100℃ | Standard grade: -35℃~+100℃ |
| Reciprocating Speed | ≤0.5m/s; Low friction version ≤1m/s | Suitable for low-speed heavy load |
| Compatible Media | Mineral hydraulic oil, lubricating oil, HFD-R/HFD-U fire-resistant hydraulic fluid | Not fit for strong acid, alkali, ester & alcohol liquid |
| Size Range | Standard: φ6 ~ φ250mm; Custom size up to φ1000mm | Size mark: Inner d × Outer D × Height H |
4. Key Advantages
- Strong anti-extrusion capacity, avoid lip turnover under high pressure
- Superior abrasion resistance, service life 3~5 times longer than ordinary NBR seals
- Low friction coefficient, effectively prevent stick-slip movement
- Bidirectional sealing function, simplify cylinder structure design
- Self-lubricating lip structure, stable oil film to reduce abrasion
- Two-piece design, stable sealing performance after long-time operation
5. Application
Hydraulic cylinders for:
Construction machinery (excavator, loader), injection molding machine, die casting machine, hydraulic press, metallurgical equipment, mining machinery.
Main installation position: Piston rod seal, piston seal, buffer sealing system.
Construction machinery (excavator, loader), injection molding machine, die casting machine, hydraulic press, metallurgical equipment, mining machinery.
Main installation position: Piston rod seal, piston seal, buffer sealing system.
6. Groove Design Reference
- URB-R Rod Seal: Groove Dia G = d + 2H; Groove Width W = H × 1.05~1.1
- URB-P Piston Seal: Groove Dia G = D - 2H; Groove Width W = H × 1.05~1.1 Surface Requirement: Rod surface Ra ≤0.4μm; Cylinder bore Ra ≤0.8μm Groove fillet: R0.2~R0.5; Assembly chamfer: C0.5~C1
7. Selection Guide
- Confirm type: URB-R rod seal / URB-P piston seal
- PU Material Option ▫ Polyester AU: Standard, good mineral oil resistance ▫ Polyether EU: For humid, outdoor environment, anti-hydrolysis ▫ Modified PU: For high temperature working condition
- Hardness Suggestion ≤10MPa: 85~90 Shore A 10~40MPa:90~95 Shore A ＞40MPa:95 Shore A + anti-extrusion back-up ring
- Provide exact dimension (d×D×H), working pressure, temperature and medium when inquiry.
九、Installation & Maintenance
- Install the sealing lip towards pressure side
- Use professional assembly tools to prevent lip scratch
- Keep groove clean without burrs, lubricate with hydraulic oil during assembly
- Replacement cycle: Heavy duty:1~2 years; Light duty:3~5 years
8. Common Troubleshooting
- Oil Leakage: Wrong dimension, damaged lip, rough surface or improper material → Recheck size & material
- Seal Extrusion: Overpressure, insufficient groove width, lack of back-up ring → Add back-up ring, optimize groove
- Stick-slip: Low speed (<0.1m/s), poor lubrication → Adopt low friction PU grade
9. Interchangeable Seal Models
Japanese series: NOK UHS, UNS, Sakagami SPG, Valqua U-PK
European & American: Parker B3, Trelleborg M2, HPS UBR
Domestic equivalent: YXd, YXp, URU, URUA
10. Custom Service
- Custom size, hardness, PU material available
-
Support small batch & bulk wholesale
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Provide drawing support, technical parameter consultation
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