| 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 in dozer applications. |
| Komatsu Equipment Model | Specific Application |
|---|---|
| Komatsu D31EX-21, D31PX-21 | Blade Lift (Hoist) Cylinders |
| Komatsu D37EX-21, D37PX-21 | Blade Lift (Hoist) Cylinders |
| Note: | This kit is a direct replacement for Komatsu part numbers 246-5917 and 707-98-22910. It is specifically designed for the LIFT/HOIST CYLINDERS on the listed D31-21 and D37-21 series dozers. Verify your machine model and that you are servicing the LIFT cylinders, not the angle/tilt cylinders. |
| 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 (Heavy-Duty) | Polyurethane (PU) | Black | 88 Shore A | Excludes abrasive dirt, mud, and debris |
| Buffer Ring | Polyurethane (CU) | Black | 88 Shore A | Dampens pressure spikes to protect rod seal |
| O-Ring Kit (Assorted) | Nitrile Rubber (NBR) | Black | 70 Shore A | Static sealing for gland, end cap, and 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 under pressure |
| Application Sector | Primary Equipment | Symptoms Addressed by This Kit |
|---|---|---|
| Earthmoving & Grading | Komatsu D31-21, D37-21 Dozers | Inability to hold blade height ("drift" or "sinking"), visible hydraulic oil leakage from the rod gland, slow or weak blade lifting power, oil spots under the dozer. |
| Construction & Mining | Bulldozer Blade Lift/Hoist Cylinders | Loss of precise grading control, increased hydraulic fluid consumption, reduced machine pushing efficiency and productivity. |
| Heavy Equipment Repair | Scheduled Maintenance & Leak Repair | Restores factory sealing to ensure reliable blade control, prevents environmental fluid loss, and provides a cost-effective alternative to complete cylinder replacement. |
| NO | Number | Name | Qty |
| G-1 | 707-00-XA011 | CYLINDER GROUP,L.H. | 1 |
| G-2 | 707-00-XA021 | CYLINDER GROUP,R.H. | 1 |
| ==================== | |||
| 707-00-0A011 | CYLINDER ASS'Y,L.H. | 1 | |
| 707-00-0A021 | CYLINDER ASS'Y,R.H. | 1 | |
| 1 | 707-11-85251 | • CYLINDER,L.H. | 1 |
| 1 | 707-11-85261 | • CYLINDER,R.H. | 1 |
| 2 | 07143-10405 | • BUSHING | 1 |
| 3 | 07145-00045 | • SEAL,DUST (KIT) | 2 |
| 4 | 707-29-85131 | • HEAD,CYLINDER | 1 |
| 5 | 07177-04025 | • BUSHING | 1 |
| 6 | 707-51-40210 | • PACKING,ROD (KIT) | 1 |
| 7 | 198-63-75190 | • SEAL,DUST (KIT) | 1 |
| 8 | 07179-12052 | • RING,SNAP | 1 |
| 9 | 07000-12080 | • O-RING (KIT) | 1 |
| 10 | 707-35-52770 | • RING,BACK-UP (KIT) | 1 |
| 11 | 07000-12085 | • O-RING (KIT) | 1 |
| 12 | 721-58-40940 | • ROD,PISTON | 1 |
| 13 | 07143-10405 | • BUSHING | 1 |
| 14 | 07145-00045 | • SEAL,DUST (KIT) | 2 |
| 15 | 707-36-85070 | • PISTON | 1 |
| 16 | 707-44-85180 | • RING,PISTON (KIT) | 1 |
| 17 | 707-39-85120 | • RING,WEAR (KIT) | 1 |
| 18 | 707-67-30030 | • NUT | 1 |
| 19 | 02896-11012 | • O-RING (KIT) | 1 |
| 20 | 20U-62-41620 | ELBOW,L.H. | 1 |
| 21 | 07002-11823 | O-RING (KIT) | 1 |
| 22 | 02896-11012 | O-RING (KIT) | 1 |
| ==================== | |||
| 707-98-22910 | SERVICE KIT | 2 |
Machine Secure & Pressure Relief: Park the dozer on a firm, level surface. Lower the blade completely to the ground to relieve all hydraulic pressure. Engage the parking brake and block the tracks.
Controlled Disassembly: Disconnect and cap hydraulic lines. Properly support the cylinder rod before removing the mounting pins. Note the orientation and order of all components.
Cleanliness Protocol: Disassembly and assembly must be performed in a clean area. Thoroughly clean all metal components and the workbench to prevent contamination.
Critical Metal Inspection: Inspect the cylinder rod for any scratches, gouges, or corrosion. Check the cylinder bore (ID) for scoring, pitting, or excessive wear. Damaged metal components must be replaced prior to seal installation.
Lubricated Assembly: Soak all new elastomeric seals in clean hydraulic fluid. Lightly lubricate all seal grooves and sliding surfaces before installing new seals.
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 torque wrench to tighten all bolts, gland nuts, or end caps to Komatsu's specified torque values and sequences.
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