| Application Sector | Likely Equipment & Use | Symptoms Addressed by This Kit |
|---|---|---|
| Earthmoving & Grading | Komatsu D37, D39 Series Dozers (Blade or Ripper Cylinders) | Hydraulic oil leakage from cylinder gland, cylinder drift or inability to hold position, slow or weak cylinder operation, high fluid consumption. |
| Construction & Site Development | Bulldozer Implement Control Cylinders | Loss of precise equipment control, reduced machine efficiency and productivity, fluid contamination from failed seals. |
| Heavy Equipment Maintenance | Scheduled Overhauls & Leak Repairs | Restores factory sealing performance, provides a reliable OEM-alternative for cost-effective repair, extends cylinder service life. |
| Parameter | Value / Specification |
|---|---|
| Maximum Operating Pressure | Up to 3,770 PSI (260 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) & Nitrile Rubber (NBR) |
| Seal Hardness (Dynamic) | 90-92 Shore A (Polyurethane) |
| Seal Hardness (Static) | 70 Shore A (NBR O-Rings) |
| Design Standard | Engineered to meet or exceed Komatsu's original specifications for durability and pressure retention. |
| Komatsu Equipment Model | Specific Application |
|---|---|
| Komatsu D37EX-21, D37PX-21 | Refer to Machine Service Manual for Exact Cylinder Application |
| Komatsu D39EX-21, D39PX-21 | Refer to Machine Service Manual for Exact Cylinder Application |
| Note: | This kit is a direct replacement for Komatsu OEM part number 707-98-24720. The specific cylinder application (e.g., lift, tilt, ripper) varies by machine configuration. It is critical to verify the exact component being serviced against your machine's service manual or Komatsu parts catalog using this part number. |
| Component Name | Material | Color | Durometer | Function |
|---|---|---|---|---|
| Main Piston Seal (U-Cup) | Polyurethane (AU) | Brown | 92 Shore A | Primary dynamic pressure seal on piston |
| Rod Seal (Step Seal) | Cast Polyurethane (CU) | Black | 90 Shore A | Main rod seal for pressure retention |
| Wiper/Scraper | Polyurethane (PU) | Black | 88 Shore A | Excludes abrasive contaminants |
| Buffer Ring | Polyurethane (CU) | Black | 88 Shore A | Protects rod seal from pressure surges |
| O-Ring Kit (Assorted) | Nitrile Rubber (NBR) | Black | 70 Shore A | Static sealing for gland, end cap, ports |
| Wear Ring / Guide Band | Filled PTFE | Brown | N/A | Guides piston/rod, prevents metal contact |
| Backup Rings | Nylon 6.6 | Tan/White | N/A | Prevents O-ring extrusion under pressure |
| NO | Number | Name | Qty |
| 707-00-XC050 | CYLINDER GROUP | 1 | |
| ==================== | |||
| 707-00-0C050 | CYLINDER ASS'Y | 1 | |
| 1 | 707-11-90950 | • CYLINDER | 1 |
| 2 | 113-63-42170 | • BUSHING | 1 |
| 3 | 707-29-90821 | • HEAD,CYLINDER | 1 |
| 4 | 07177-04530 | • BUSHING | 1 |
| 5 | 707-51-45210 | • PACKING,ROD (KIT) | 1 |
| 6 | 112-63-15370 | • SEAL,DUST (KIT) | 1 |
| 7 | 07179-12057 | • RING,SNAP | 1 |
| 8 | 07000-12085 | • O-RING (KIT) | 1 |
| 9 | 07146-02086 | • RING,BACK-UP | 1 |
| 10 | 07000-12090 | • O-RING (KIT) | 1 |
| 11 | 721-58-45330 | • ROD,PISTON | 1 |
| 12 | 113-63-42170 | • BUSHING | 1 |
| 13 | 707-36-90360 | • PISTON | 1 |
| 14 | 07156-00912 | • RING,WEAR (KIT) | 1 |
| 15 | 707-44-90180 | • RING,PISTON (KIT) | 1 |
| 16 | 707-67-33010 | • NUT | 1 |
| 17 | 02782-10315 | • ELBOW | 1 |
| 18 | 07002-12034 | • O-RING (KIT) | 1 |
| 19 | 02896-11009 | • O-RING (KIT) | 2 |
| ==================== | |||
| 707-98-24720 | SERVICE KIT | 2 |
Safe Depressurization & Support: Park the machine on level ground. Lower all attachments (bucket, stabilizers, backhoe) to the ground to relieve hydraulic pressure.
Clean Workspace: Perform all work in a meticulously clean environment to prevent contamination of the hydraulic system.
Documented Disassembly: Carefully disassemble the cylinder. Photograph and label each component and its orientation.
Mandatory Metal Inspection: Thoroughly inspect the cylinder rod for scratches, pitting, or scoring. Inspect the cylinder bore for wear or damage. Replace any damaged metal components before installing new seals.
Proper Seal Installation: Lubricate all new seals with clean hydraulic fluid. Use seal installation tools (cone tools, sleeves) to guide seals over threads and sharp edges without damage.
Precision Reassembly: Follow the included diagram for correct seal order and orientation. Ensure all seals are fully seated in their grooves.
Torque Specifications: Use a calibrated torque wrench. Adhere strictly to Komatsu's specified torque values and sequences for all fasteners (gland bolts, tie-rods)
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