4340621 Arm Cylinder Seal Kit for Hitachi Excavators EX400-3 -5 EX450H-5 ZX450
4340621 Arm Cylinder Seal Kit Product Overview
The 4340621 Arm Cylinder Seal Kit is a genuine OEM hydraulic seals solution for Hitachi EX400-3, EX400-5, EX450H-5, and ZX450 hydraulic excavators. This kit restores factory sealing performance to eliminate internal leakage, prevent arm drift during digging/lifting, and extend cylinder lifespan in heavy-duty mining and construction operations.
4340621 Seal Kit Technical Specifications
| Compatible Models | EX400-3 • EX400-5 • EX450H-5 • ZX450 and more |
| Cylinder Type | Arm (Stick) Cylinder Repair |
| Rod Diameter | 105mm (4.13″) |
| Bore Size | 140mm (5.51″) |
| Pressure Rating | 34.3 MPa (4,975 PSI) continuous │ 42 MPa peak |
| Temperature Range | -30°C to +120°C (-22°F to +248°F) |
| Seal Materials | Cast Polyurethane (AU90) HNBR80 O-Rings |
Hydraulic Seal Kit Contents
| Pressure-Actuated U-Cup | 34.3 MPa dynamic sealing (AU90 compound) |
| Step Seal (HNBR80) | Zero-leak rod sealing (0.004mm clearance) |
| PTFE-Coated Guide Band | Reduces friction (CoF: 0.025) |
| 4-Lip Wiper (Black PU) | Blocks 99.6% contaminants >10μm |
| Anti-Extrusion Rings | PEEK material prevents seal blowout at 42 MPa |
| Buffer Seals (FKM) | Absorbs pressure spikes during hammer drilling |
| Static Seals (HNBR80) | High-temp O-rings for gland/piston |
Key Benefits
✅ Precise Arm Control: Holds position within 0.8° after 24hrs
✅ 42 MPa Shock Resistance: Withstands peak pressures from hydraulic breakers
✅ Extended Service Life: PTFE guide bands reduce cylinder wear by 40%
✅ Contaminant Defense: Quad-lip wiper exceeds ISO 4406:18/16/13 cleanliness standard
Frequently Asked Questions (FAQ)
Q: Do you have any other excavator model repair seal kits ?
A: Yes. As the professional excavator seal kits manufacturer, we produce all the excavators repair seal kits, standard sizes and also support customization. Please tell us the part number seal kit you want.
Q: I can’t find the model I want. Are all your seal repair kits here?
A: No. We have more than tens of thousands seal kits. Here only a small part of them is shown. We have stock of all the seal kits for construction machinery. Please contact us!
Contact Us
For more information or to request a quote, please contact us or email [email protected].
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