Technical Constants & Performance Data
| Parameter | Value / Specification |
|---|---|
| Maximum Operating Pressure | Up to 4,350 PSI (300 bar) |
| Temperature Range | -40°F to 225°F (-40°C to 107°C) |
| Fluid Compatibility | Mineral-based hydraulic oils, Komatsu Super Hydraulic Fluid (KSHV), BIO HFDU fluids |
| Primary Seal Material | Polyurethane (AU), Cast Polyurethane (CU), Nitrile Rubber (NBR) |
| Seal Hardness (Dynamic) | 92-94 Shore A (Polyurethane) |
| Seal Hardness (Static) | 70 Shore A (NBR O-Rings) |
| Design Standard | Manufactured to meet or exceed Komatsu's original specifications for pressure holding, extrusion resistance, and service life. |
Exact Model Compatibility
| Komatsu Equipment Model | Likely Cylinder Application (Must Verify) |
|---|---|
| Komatsu D61EX/PX-15, D61EX/PX-12 | Likely for Blade Lift, Tilt, or Pitch Cylinders |
| Komatsu D65EX/PX-15, D65EX/PX-12 | Likely for Blade Lift, Tilt, or Pitch Cylinders |
| Komatsu D85EX/PX-15 | Likely for Blade Lift, Tilt, or Pitch Cylinders |
| Note: | This kit is a direct replacement for Komatsu OEM part number 707-98-25050. The specific cylinder application (e.g., Lift, Tilt, Pitch) varies by machine model. It is absolutely critical to verify the exact component this kit is intended for using the machine's official Komatsu service manual or parts catalog before purchase and disassembly. |
Component Specifications Table
| Component Name | Material | Color | Durometer | Function |
|---|---|---|---|---|
| Main Piston Seal (U-Cup) | Polyurethane (AU) | Brown | 94 Shore A | Primary high-pressure dynamic seal on piston |
| Rod Seal (Step Seal) | Cast Polyurethane (CU) | Black | 93 Shore A | Main rod seal for pressure retention |
| Wiper/Scraper (Heavy-Duty) | Polyurethane (PU) | Black | 90 Shore A | Excludes abrasive contaminants from rod |
| Buffer Ring | Polyurethane (CU) | Black | 90 Shore A | Protects rod seal from pressure spikes |
| O-Ring Kit (Assorted) | Nitrile Rubber (NBR) | Black | 70 Shore A | Static sealing for gland, end cap, ports |
| Wear Ring / Guide Band | Glass-Filled PTFE | Dark Brown | N/A | Centralizes piston, prevents metal contact |
| Backup Rings | Nylon 6.6 | Tan | N/A | Prevents extrusion of static O-rings |
Decompose pictures
Installation decomposition diagram
Full set of precision-molded static O-rings for all gland and port sealing points.
Essential wear guide band to ensure smooth piston travel and minimize side load.
Necessary high-pressure nylon backup rings.
Excluded Items: This is a seal and wear component kit only. It does NOT include the piston, cylinder rod, barrel, gland nut, bearings, bolts, pins, or any other metal parts or hardware.
Machine Secure & Pressure Relief: Park the dozer on firm, level ground. Lower the blade fully to relieve all hydraulic pressure. Engage parking brake and block tracks.
Cleanliness Protocol: Perform disassembly and assembly in an impeccably clean, dust-controlled environment. Abrasive contamination is the leading cause of seal failure.
Documented Disassembly: Carefully disassemble the cylinder. Photograph and note the exact order and orientation of all components, especially the seal stack in the gland.
Critical Metal Inspection: Inspect the cylinder rod for scratches, gouges, or corrosion. Check the cylinder bore (ID) for scoring, pitting, or excessive wear. Damaged metal components MUST be replaced.
Lubricated Assembly: Soak all new elastomeric seals in clean hydraulic fluid. Lightly lubricate all seal grooves and sliding surfaces before installation.
Proper Tool Use: Use seal installation tools (cone tools, picks, sleeves) to carefully install seals without cutting, stretching, or rolling them over sharp edges.
Torque to Specification: During reassembly, use a calibrated torque wrench. Adhere strictly to Komatsu's specified torque values and sequences for all fasteners.
Frequently Asked Question
Q1: Which Komatsu excavator models use the 707-98-25050 hydraulic cylinder seal kit?
A: This premium seal kit is designed for specific Komatsu excavator hydraulic cylinders requiring OEM part number 707-98-25050 (also listed as 7079825050). Please verify with your machine model and cylinder part number before ordering.
Q2: Is this an OEM or aftermarket seal kit?
A: It is a premium OEM-grade replacement kit, manufactured to meet or exceed original Komatsu quality standards for sealing performance, durability, and precise fit.
Q3: What makes this a "premium" hydraulic cylinder seal kit?
A: The premium kit features advanced polyurethane seals and high-grade rubber compounds designed for extended service life, superior leak prevention, and performance in extreme hydraulic pressures and temperatures.
Q4: What is included in the COGENG 707-98-25050 seal kit?
A: The kit includes all necessary rod seals, piston seals, wipers, O-rings, and backup rings for a complete hydraulic cylinder rebuild – ready to install with no missing components.
Q5: How do I purchase the COGENG 707-98-25050 premium hydraulic cylinder seal kit?
A: Contact us with your Komatsu machine model and cylinder details for fitment verification, then order directly through our website or sales team for fast shipping.
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