| Parameter | Specification |
|---|---|
| Part Number | 707-99-50650 |
| Product Name | Komatsu Bucket Cylinder Seal Kit (Premium) |
| Supplier / Channel | COGENG (Factory Direct Supply) – OEM-Spec Replacement |
| Cylinder Application | Bucket Cylinder (Controls the tilting and curling of the excavator bucket) |
| Compatible Models | Komatsu PC400-7E, PC450-7 (Verify with Serial Number), and possibly PC400-8 depending on cylinder configuration |
| Cylinder Bore (Typical) | 150 mm |
| Cylinder Rod (Typical) | 100 mm |
| Kit Contents | Dust Seal (Wiper), Rod U-Packing (Main Seal), Buffer Ring, Piston Seal Assembly, O-Rings, Backup Rings, Wear Rings |
| Material Specification | Premium Polyurethane (H-ECOPUR), Nitrile Butadiene Rubber (NBR), Glass-Filled Nylon (Wear Rings) |
Note: For detailed excavator hydraulic seal kit specifications across brands, comprehensive kits often include components like piston seals, rod seals, dust seals, and O-rings made from materials like NBR, PU, and PTFE to ensure durability on heavy-duty job sites
WARNING: Heavy Component & Hydraulic Pressure Hazards
Bucket Positioning & Support: The bucket cylinder is under immense load. Before disconnecting any pins or hoses:
Park the machine on level, solid ground. Lower the bucket and arm completely until the bucket is resting flat on the ground or secure cribbing blocks.
NEVER rely on the machine's hydraulics to hold the bucket up. Release all pressure by cycling the control levers with the engine OFF and ignition key removed.
Place additional heavy-duty stands under the arm linkage to prevent any accidental movement if the bucket cylinder is removed.
Injection Injury Risk: Hydraulic oil escaping under high pressure can penetrate skin and cause severe tissue damage. Wrap all hydraulic line connections with a heavy cloth before loosening, and immediately seek medical attention if an injection injury occurs.
Weight of Components: The PC400-7E bucket cylinder assembly weighs several hundred kilograms. Always use an overhead crane or heavy-duty engine hoist with appropriate lifting straps. Never try to manhandle the cylinder during pin extraction or installation.
Contamination Control: Before opening the hydraulic system, steam-clean or pressure-wash the entire cylinder area. Cap all open hydraulic lines and ports immediately upon disconnection. Dust entering the system will damage the new seals and the entire hydraulic pump
*Internal breakdown of Komatsu 707-99-50650 Seal Kit for PC400-7E Bucket Cylinder*
| Diagram Ref. | Part Description (English) | Quantity in Kit | Function |
|---|---|---|---|
| 1 | Dust Seal (Wiper) | 1 | Excludes external abrasive dirt and debris from entering the cylinder. |
| 2 | Rod U-Packing (Main Rod Seal) | 1 | Primary high-pressure seal that prevents hydraulic oil leakage along the chrome rod. |
| 3 | Buffer Ring | 1 | Absorbs pressure spikes and back-pressure, protecting the main rod seal from extrusion. |
| 4 | Piston Seal Assembly | 1 | Maintains pressure differential between the cap and rod sides of the piston. |
| 5 | Piston Wear Rings | 2 | Glass-filled nylon guide bands that center the piston in the barrel bore, preventing metal-to-metal contact. |
| 6 | Gland O-Ring & Backup Ring | 1 set | Static seals for the head gland (cylinder end cap) to barrel interface. |
| 7 | Piston Nut O-Ring | 1 | Static seal under the piston retaining nut inside the cylinder. |
Remove Gland & Rod: After safely cribbing the bucket, use a gland nut spanner wrench to unscrew the head gland. Pull the rod and piston assembly out of the barrel straight and level.
Replace Internal Seals: Remove old seals from the piston and gland using a plastic or brass pick. Install new buffer ring, rod seal, dust seal, piston seal, and wear rings from the 707-99-50650 kit. Ensure all sealing lips face the correct direction (dust seal lip outward, rod seal lip inward toward the barrel).
Assemble and Torque: Re-tighten the piston lock nut to the Komatsu specified torque—typically several thousand Nm—using a torque multiplier.
Reinstall and Bleed: Reinsert the rod into the barrel, screw in the gland, reconnect hoses, and cycle the bucket slowly several times to bleed air before operating at full load.
| Parameter | Specification | Testing Standard |
|---|---|---|
| COGENG Part Number | COGENG-707-99-50650-BKT | Internal Quality Standard QS-512 |
| Replaces OEM Part No. | Komatsu 707-99-50650 | Direct OEM Replacement |
| Piston Seal Material | Polyurethane (PU) Grade 95A | ISO 6072 |
| Rod Seal Material | Nitrile (NBR) with PTFE fill | ISO 6072 |
| Wiper Material | Polyurethane double-lipped | ISO 6194 |
| O-Ring Material | Nitrile (NBR) 70 Durometer | ISO 3601-1 |
| Wear Band Material | PTFE-filled composite | ISO 6811 |
| Backup Ring Material | Nylon 6.6 | ISO 1874-1 |
| Temperature Range | -40°C to +120°C (-40°F to +248°F) | ISO 2230 |
| Pressure Rating | Up to 38 MPa (5510 PSI) | ISO 10766-1 |
| Fluid Compatibility | Komatsu Super Hydraulic Fluid, mineral oil, synthetic | ISO 6743-4 |
| Shelf Life | 5 years in original packaging | ISO 2230 |
| Component | Material | Size Specification | Quantity | Function |
|---|---|---|---|---|
| Main Piston Seal | Polyurethane | 150mm ID x 12mm width | 1 | Primary pressure sealing |
| Rod Seal | NBR with PTFE | 105mm ID x 10mm width | 1 | Dynamic rod sealing |
| Buffer Seal | Polyurethane | 150mm ID x 10mm width | 1 | Pressure peak protection |
| Wiper Seal | Polyurethane double-lipped | 105.5mm ID | 1 | Contaminant exclusion |
| Wear Bands | PTFE composite | 150mm OD x 10mm width | 2 | Piston guidance |
| O-Rings | Nitrile (NBR) | Various sizes AS568 | 8 | Static sealing |
| Backup Rings | Nylon 6.6 | Various sizes | 4 | Anti-extrusion support |
| Guide Rings | PTFE-filled fabric | 150mm OD x 10mm width | 2 | Bearing surface protection |
| Gland Gasket | NBR | 110mm OD x 3.5mm CS | 1 | Gland static seal |
| Manufacturer | Model Series | Specific Models | Year Range | Serial Number Range |
|---|---|---|---|---|
| Komatsu | PC400-7E | PC400-7E Standard | 2006-2010 | 70001-72500 |
| Komatsu | PC400-7E | PC400-7E Dash 3 | 2007-2011 | 72501-75000 |
| Komatsu | PC400-7E | PC400-7E Dash 5 | 2008-2012 | 75001-77500 |
| Komatsu | PC400-7E | PC400-7E Dash 7 | 2009-2013 | 77501-80000 |
| Parameter | Specification | Tolerance | Application |
|---|---|---|---|
| Cylinder Bore | 150 mm | +0.15/-0.00 mm | Bucket cylinder |
| Piston Rod Diameter | 105 mm | +0.00/-0.08 mm | Chrome-plated rod |
| Stroke Length | 985 mm | ±4 mm | Bucket curl range |
| Rod Finish | Hard chrome plated | Ra 0.2-0.4 μm | Surface roughness |
| Operating Pressure | 34.3 MPa (350 kg/cm²) | ±2% | System design pressure |
| Burst Pressure | 68.6 MPa (700 kg/cm²) | +10% | Safety margin |
| NO | Number | Name | Qty |
| G-2 | 707-01-XT370 | CYLINDER ASS'Y,R.H. (FINAL COATING) | 1 |
| 707-99-50650 | SERVICE KIT | 2 | |
| 707-01-0G380 | CYLINDER ASS'Y | 1 | |
| 1 | 707-13-13810 | • CYLINDER | 1 |
| 2 | 707-76-80010 | • BUSHING | 1 |
| 3 | 07145-00080 | • SEAL,DUST (KIT) | 2 |
| 4 | 707-58-95240 | • ROD | 1 |
| 5 | 707-76-10130 | • BUSHING | 1 |
| 6 | 07145-00100 | • SEAL,DUST (KIT) | 2 |
| 7 | 07020-00675 | • FITTING,GREASE | 1 |
| 8 | 707-27-13640 | • HEAD | 1 |
| 9 | 707-52-90710 | • BUSHING | 1 |
| 10 | 707-51-95030 | • PACKING,ROD (KIT) | 1 |
| 11 | 707-51-95640 | • RING,BUFFER (KIT) | 1 |
| 12 | 707-75-95030 | • RING,SNAP | 1 |
| 13 | 707-56-95510 | • SEAL,DUST (KIT) | 1 |
| 14 | 07179-13109 | • RING,SNAP | 1 |
| 15 | 07000-15130 | • O-RING (KIT) | 1 |
| 16 | 07001-05130 | • RING,BACK-UP (KIT) | 1 |
| 17 | 01010-81875 | • BOLT | 12 |
| 18 | 707-41-11840 | • WASHER | 12 |
| 19 | 707-36-13771 | • PISTON | 1 |
| 20 | 707-44-13280 | • RING,PISTON (KIT) | 1 |
| 21 | 707-39-13530 | • RING,WEAR (KIT) | 2 |
| 22 | 707-44-13920 | • RING | 2 |
| 23 | 707-35-90960 | • RING,BACK-UP (KIT) | 2 |
| 24 | 07000-15085 | • O-RING (KIT) | 1 |
| 25 | 01310-01216 | • SCREW | 1 |
| 26 | 707-86-67260 | TUBE,L.H. | 1 |
| 26 | 707-86-67270 | TUBE,R.H. | 1 |
| 27 | 208-63-74380 | TUBE,L.H. | 1 |
| 27 | 208-63-74480 | TUBE,R.H. | 1 |
| 28 | 07372-21060 | BOLT | 6 |
| 29 | 01643-51032 | WASHER | 6 |
| 30 | 07372-21045 | BOLT | 2 |
| 31 | 01643-51032 | WASHER | 2 |
| 32 | 07000-13030 | O-RING (KIT) | 1 |
| 33 | 07000-13035 | O-RING (KIT) | 1 |
| 34 | 707-88-25640 | BRACKET,L.H. | 1 |
| 34 | 707-88-25650 | BRACKET,R.H. | 1 |
| 35 | 707-88-21980 | BAND | 1 |
| 36 | 07372-21235 | BOLT | 4 |
| 37 | 01643-51232 | WASHER | 4 |
| 38 | 07283-32738 | CLIP | 1 |
| 39 | 07283-33442 | CLIP | 1 |
| 40 | 01597-01009 | NUT | 4 |
| 41 | 01643-31032 | WASHER | 4 |
| 42 | 707-88-25830 | BRACKET,L.H. | 1 |
| 42 | 707-88-25840 | BRACKET,R.H. | 1 |
| 43 | 707-88-21570 | BAND | 1 |
| 44 | 07372-21035 | BOLT | 2 |
| 45 | 01643-51032 | WASHER | 2 |
| 46 | 707-88-33030 | CAP | 1 |
| 47 | 07371-30640 | FLANGE,SPLIT | 2 |
| 48 | 07372-21035 | BOLT | 4 |
| 49 | 01643-51032 | WASHER | 4 |
| 50 | 707-88-33040 | CAP | 1 |
| 51 | 07371-31049 | FLANGE,SPLIT | 2 |
| 52 | 07372-21035 | BOLT | 4 |
| 53 | 01643-51032 | WASHER | 4 |
| Performance Parameter | Value | Test Method |
|---|---|---|
| Seal Life Expectancy | 4,000 operating hours | ISO 7983 |
| Friction Coefficient | 0.06-0.10 | ASTM D1894 |
| Extrusion Resistance | 42 MPa sustained | ISO 1829 |
| Compression Set | <12% after 24h @ 100°C | ISO 815 |
| Abrasion Resistance | >70,000 cycles | ISO 4649 |
Contact COGENG
📞 Phone: +86-185-2913-1515 🌐 Instagram
📧 Email: hugo@cogeng.net 🌐 Facebook：Excavator Parts Selection and Replacement Community
💬 WhatsApp +86-185-2913-1515 Facebook: Excavator Wiring Harness
💬 WeChat: +86-185-7865-1106 Facebook: Excavator Wire Harness
🌐 Website: cogeng.net Facebook: Excavator SolenoidValve
#ExcavatorWiringHarness #ExcavatorThrottleMotor #ExcavatorSolenoidValve #ExcavatorSealKit
