| Parameter | Value / Specification |
|---|---|
| Maximum System Pressure | Up to 5,220 PSI (360 bar) |
| Temperature Range | -40°F to 225°F (-40°C to 107°C) |
| Fluid Compatibility | Mineral-based hydraulic oils, Komatsu Super Hydraulic Fluid (KSHV), synthetic fluids |
| Primary Seal Materials | Polyurethane (AU/CU), Nitrile Rubber (NBR), PTFE composites -1 |
| Seal Hardness (Dynamic) | 90-94 Shore A (Polyurethane) |
| Seal Hardness (Static) | 70 Shore A (NBR O-Rings) |
| Manufacturing Standards | ISO 3601, AS568A, ISO 7425 |
| Quality Assurance | Manufactured to meet or exceed original Komatsu technical specifications |
| Komatsu Excavator Model | OEM Part Number | Cylinder Application |
|---|---|---|
| Komatsu PC400-7 | 707-98-43290 | Bucket Cylinder |
| Komatsu PC400-8 | 707-98-43290 | Bucket Cylinder |
| Note: | This kit is a direct replacement for Komatsu OEM part number 707-98-43290. It is designed specifically for the BUCKET CYLINDER on the PC400-7 and PC400-8 excavator models. Verify your machine's model and serial number before installation. |
| Component Name | Material Specification | Standard | Primary Function |
|---|---|---|---|
| Piston Seal | Premium Polyurethane | ISO 7425-1 | Main dynamic pressure seal; maintains pressure between cylinder chambers |
| Rod Seal | Cast Polyurethane Composite | ISO 6547 | Primary rod sealing; prevents hydraulic oil from leaking out of the cylinder |
| Wiper/Scraper | Heavy-Duty Polyurethane | ISO 6195 | Contaminant exclusion; blocks dirt and debris from entering the cylinder |
| Buffer Ring | Polyurethane (CU) | - | Absorbs pressure spikes and extends rod seal life |
| Wear Ring/Guide Band | Glass-Filled PTFE | - | Piston/rod guidance; prevents metal-to-metal contact |
| O-Ring Set | Nitrile Rubber (NBR) | AS568A/ISO 3601 | Static sealing for gland, end cap, ports, and fittings |
| Backup Rings | Engineering-Grade Nylon | - | Anti-extrusion protection for high-pressure applications |
| Dust Seal | Polyurethane | - | Secondary contaminant exclusion |
Full complement of seals for complete bucket cylinder rebuild
All required O-rings and backup rings for gland and port assembly
Multi-layer protection system ensuring longer equipment uptime and reduced risk of hydraulic failure -1
Excluded Items: This kit contains seal components only. Piston, rod, barrel, gland, bearings, bolts, and other metal parts are not included.
Application Verification: Confirm 707-98-43290 is the correct part number for your PC400-7 or PC400-8 bucket cylinder using official Komatsu documentation.
System Depressurization: Completely relieve all hydraulic pressure before disassembly. Park excavator on level ground and lower the bucket fully.
Clean Work Environment: Maintain meticulous cleanliness throughout the repair process. Hydraulic system contamination is a primary cause of seal failure
Documented Disassembly: Carefully disassemble the bucket cylinder. Photograph and note the exact order and orientation of all components.
Component Inspection: Thoroughly inspect all metal components (rod, bore, piston) for wear, scoring, or damage. New seals cannot compensate for worn or damaged metal surfaces.
Proper Installation: Use correct tools and techniques to prevent seal damage during assembly. Lubricate all seals with clean hydraulic fluid before installation.
Torque Compliance: Follow OEM torque specifications for all fasteners.
System Testing: Perform appropriate pressure testing before returning to service to validate seal integrity.
Critical Specific Warnings
MODEL-SPECIFIC APPLICATION: This kit is ONLY for the BUCKET CYLINDER on Komatsu PC400-7 and PC400-8 excavators. Do not use on boom cylinders, arm cylinders, or other excavator models without verification. Incorrect application will cause failure.
METAL SURFACE CONDITION: This seal kit cannot compensate for worn or damaged cylinder components. Ensure all metal surfaces are within serviceable limits before installation
CONTAMINATION CONTROL: Even microscopic debris introduced during assembly will act as an abrasive, destroying new seals. Maintain absolute cleanliness during installation
PRESSURE SAFETY: Always ensure complete system depressurization before beginning any repair work.
| Application Sector | Machine Series | Cylinder Type | Key Benefits |
|---|---|---|---|
| Heavy Excavation & Earthmoving | Komatsu PC400-7 / PC400-8 | Bucket Cylinder | Restores maximum digging force and breakout power |
| Mining & Quarry Operations | Komatsu PC400 Series Excavators | Bucket Curling Control | Reduces downtime, extends cylinder service intervals |
| Heavy Construction | Large Hydraulic Excavators | Implement Cylinder Rebuild | Cost-effective OEM alternative, reliable performance |
| Equipment Maintenance | Scheduled Overhauls & Leak Repair | Bucket Cylinder Seals | Prevents environmental contamination, reduces operating costs |
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