- CN
| Parameter | Specification | Testing Standard |
|---|---|---|
| Operating Pressure Range | 5-24 MPa (725-3,480 PSI) | ISO 10766 |
| Temperature Range | -30°C to +100°C (-22°F to +212°F) | ASTM D2000 |
| Bore Diameter | 70mm (±0.015mm) | ISO 286-2 |
| Rod Diameter | 35mm (-0/+0.010mm) | ISO 286-2 |
| Stroke Length (Typical) | 300-400mm (varies by application) | Komatsu specification |
| Seal Material Hardness | 82-90 Shore A (component specific) | ASTM D2240 |
| Pressure Cycle Rating | 180,000 cycles at 20 MPa | ISO 10767-1 |
| Friction Coefficient | 0.15-0.22 (optimized for compact dozer operation) | ASTM D1894 modified |
| Contaminant Exclusion | >94% efficiency for >15µm particles | ISO 4548-12 |
| Drift Rate | ≤3 mm/minute at 20 MPa | Proprietary test method |
| Abrasion Resistance | ≤65 mm³ loss (Taber, CS-17 wheel) | ASTM D4060 |
| Thermal Conductivity | 0.25-0.32 W/m·K | ASTM E1225 |
| Service Life | 2,800-4,200 hours in typical D21-8 service | Field validation data |
| Response Time | <0.5 seconds for full cylinder movement | Field validation data |
| Component | COGENG Part Number | Material | Dimensions | Special Features | Quantity |
|---|---|---|---|---|---|
| 35x70 Piston Seal | CG-PS-12760-01 | HNBR with reinforcement | ID: 70mm (bore specific) | Optimized for 70mm bore | 2 |
| 35x70 Rod Seal | CG-RS-12760-01 | Polyurethane (EU) | ID: 35mm (rod specific) | Low friction, 35mm optimized | 2 |
| Compact Wiper | CG-CW-12760-01 | Dual-density PU | 35-40mm range | Double-lip design for small dozer | 1 |
| 35x70 Wear Bands | CG-WB-12760-01 | Bronze-PTFE composite | Width: 12mm | Proper clearance for 70mm bore | 2 |
| Backup Rings | CG-BR-12760-01 | Glass-filled PTFE | Groove specific | Anti-extrusion for 35mm rod | 4 |
| Component | Function | Material | D21-8 Specification |
|---|---|---|---|
| Compact Load Compensator | Adjusts seal pressure for small dozer loads | Microcellular PU | 84 ± 3 Shore A |
| Small Cylinder Guide | Maintains alignment in compact applications | Oil-impregnated bronze | 0.08-0.15mm oil capacity |
| Moderate Impact Cushion | Protects during light impact loads | Energy-absorbing TPU | 0.2 second activation |
| D21 Linkage Seal | Pivot point protection for D21 series | HNBR with fabric backing | D21-8 specific linkage |
| Component Type | Material Specification | Quantity | D21-8 Application |
|---|---|---|---|
| Static O-Rings | FKM (Grade 70) | 6 | Hydraulic connections |
| Port Seals | HNBR with anti-extrusion | 4 | High-pressure ports |
| Gland Gasket | Fiber-reinforced composite | 1 | Gland interface sealing |
| Thread Sealant | PTFE paste | 1 kit | Fitting installation |
| Retaining Clips | Spring steel | 2 | Component retention |
| Component | Purpose | Included | Usage |
|---|---|---|---|
| 35mm Installation Cone | Rod seal protection | 1 | Prevents 35mm seal damage |
| 70mm Alignment Sleeve | Piston seal installation | 1 | Ensures proper 70mm seal alignment |
| Groove Cleaner Set | Groove preparation | 3 pieces | Removes old seal material |
| Assembly Lubricant | Installation aid | 40g | Proper seal seating for 35x70 |
| NO | Number | Name | Qty |
| G-1 | 707-00-XE980 | CYLINDER GROUP,L.H. | 1 |
| G-1 | 707-00-XE990 | CYLINDER GROUP,R.H. | 1 |
| ==================== | |||
| 707-00-0E980 | CYLINDER ASS'Y,L.H. | 1 | |
| 707-00-0E990 | CYLINDER ASS'Y,R.H. | 1 | |
| 1 | 721-11-70870 | • CYLINDER,L.H. | 1 |
| 721-11-70880 | • CYLINDER,R.H. | 1 | |
| 2 | 02896-11009 | • O-RING (KIT) | 2 |
| 3 | 07143-10304 | • BUSHING | 1 |
| 4 | 07145-00035 | • SEAL,DUST (KIT) | 2 |
| 5 | 707-29-70821 | • HEAD,CYLINDER | 1 |
| 6 | 07177-03525 | • BUSHING | 1 |
| 7 | 707-51-35210 | • PACKING,ROD (KIT) | 1 |
| 8 | 175-63-75190 | • SEAL,DUST (KIT) | 1 |
| 9 | 07179-12047 | • RING,SNAP | 1 |
| 10 | 07000-12065 | • O-RING (KIT) | 1 |
| 11 | 07146-02066 | • RING,BACK-UP (KIT) | 1 |
| 12 | 07000-12070 | • O-RING (KIT) | 1 |
| 13 | 721-58-35450 | • ROD,PISTON | 1 |
| 14 | 07143-10304 | • BUSHING | 1 |
| 15 | 07145-00035 | • SEAL,DUST (KIT) | 2 |
| 16 | 707-36-70930 | • PISTON | 1 |
| 17 | 707-44-70070 | • RING,PISTON (KIT) | 1 |
| 18 | 07156-00710 | • RING,WEAR (KIT) | 1 |
| 19 | 707-67-24010 | • NUT | 1 |
| 20 | 707-86-39370 | TUBE,L.H. | 1 |
| 707-86-39390 | TUBE,R.H. | 1 | |
| 21 | 707-86-39380 | TUBE,L.H. | 1 |
| 707-86-39400 | TUBE,R.H. | 1 | |
| 22 | 02896-11009 | O-RING (KIT) | 2 |
| 23 | 01010-81020 | BOLT | 2 |
| 24 | 01643-31032 | WASHER | 2 |
| ==================== | |||
| SERVICE KIT | |||
| K | 707-98-12760 | SERVICE KIT | 1 |
⚠️ 35x70mm CYLINDER REQUIREMENTS:
ONLY for 35x70mm cylinders on D21A-8/D21P-8
REQUIRED: Follow Komatsu D21-8 service manual exactly
MANDATORY: Use proper support for compact dozer blade
CRITICAL: Verify 35mm and 70mm measurements before installation
⚠️ SIZE-SPECIFIC CONSIDERATIONS:
35mm rod: Requires precise handling and installation
70mm bore: Must be within specification for seal life
Compact space: Requires careful work practices
D21-8 specific: Different from other D21 models
⚠️ SAFETY CONSIDERATIONS:
Blade can fall if not properly supported
Hydraulic pressure can be retained in system
35mm pins require proper handling
Compact dozer stability important during service
