| Item | Specification / Value |
|---|---|
| COGENG Part Number | 707-99-64520 |
| OEM Reference | Komatsu Genuine 707-99-64520 |
| Application | Dump (Tilt) Cylinder & Bucket Pitch Cylinder Rebuild |
| Maximum System Pressure | 32 MPa (4,641 PSI) |
| Temperature Range (Continuous) | -35°C to +115°C |
| Primary Dynamic Seal Material | Polyurethane (PU) |
| Static Seal & Special Ring Material | Fluorocarbon (FKM) / Nitrile (NBR) |
| Wear Ring / Guide Material | Glass-Filled PTFE |
| Kit Inclusions | Piston seals, rod seals, wipers, O-rings, backup rings, wear bands, gland seals |
| Unit of Sale | Complete seal kit for one cylinder |
| Component Name | Material | Hardness (Shore A) / Property | Quantity per Kit |
|---|---|---|---|
| Main Piston Seal (U-Cup) | Polyurethane (PU) | 92 ± 5 | 2 |
| Main Rod Seal (U-Cup) | Polyurethane (PU) | 90 ± 5 | 2 |
| High-Temp Rod Seal | Fluorocarbon (FKM) | 75 ± 5 | 1 (if applicable) |
| Wiper / Scraper | Polyurethane (PU) | 95 ± 5 | 1 |
| Static O-Ring (Various) | Nitrile (NBR) | 70 ± 5 | 6-8 |
| Piston Wear Band | Glass-Filled PTFE | High Load, Low Wear | 2 |
| Rod Guide / Bearing Ring | Glass-Filled PTFE | Wear Resistant | 2 |
| Anti-Extrusion Backup Ring | Filled PTFE | - | 4 |
| Compatible Model Series | Specific Compatible Models (Komatsu Wheel Loaders) | Primary Cylinder Application |
|---|---|---|
| WA350 Series | WA350-3A (Specific serial number range) | Dump (Tilt) Cylinders |
| WA380 Series | WA380-3 (Specific serial number range) | Dump (Tilt) Cylinders & Bucket Pitch Cylinders |
| Note: | This kit is specifically designed for the dump/tilt and bucket pitch cylinders on the listed models. Critical: Always match your machine's model, serial number, and the original cylinder part number (707-99-64520) before installation. Compatibility can vary based on manufacturing year and specific cylinder configuration. |
| NO | Number | Name | Qty |
| 707-99-64520 | • SERVICE KIT | 1 | |
| 707-01-02561 | CYLINDER ASS'Y | 1 | |
| 707-01-08310 | |||
| 1 | 707-13-18270 | • CYLINDER | 1 |
| 2 | 707-76-11010 | • BUSHING | 2 |
| 3 | 707-27-18140 | • HEAD,CYLINDER | 1 |
| 4 | 707-52-90680 | • BUSHING | 1 |
| 5 | 707-51-90030 | • PACKING,ROD | 1 |
| 6 | 195-63-94170 | • SEAL,DUST | 1 |
| 7 | 07179-13104 | • RING,SNAP | 1 |
| 8 | 07000-15170 | • O-RING | 1 |
| 9 | 07146-05172 | • RING,BACK-UP | 1 |
| 10 | 01010-81865 | • BOLT | 12 |
| 11 | 01643-31845 | • WASHER | 12 |
| 12 | 707-58-90610 | • ROD,PISTON | 1 |
| 14 | 07000-12070 | • O-RING | 1 |
| 15 | 707-35-52910 | • RING,BACK-UP | 2 |
| 16 | 707-36-18400 | • PISTON | 1 |
| 17 | 707-44-18180 | • RING,PISTON | 1 |
| 18 | 07156-01822 | • RING,WEAR | 1 |
| 19 | 707-40-18070 | • SPACER | 2 |
| 20 | 01010-61240 | • BOLT | 6 |
| 21 | 707-51-90640 | • RING,BUFFER | 1 |
Maximum Operating Pressure: 32 MPa (≈ 4,641 PSI) – rated for high-load bucket operations.
Temperature Range: -35°C to +115°C (-31°F to 239°F) – stable across varied working environments.
Primary Seal Material: Polyurethane (AU/EU) for exceptional abrasion resistance and high-pressure capability.
Secondary Seal Material: Fluorocarbon (FKM/Viton®) for sections exposed to higher heat or specific fluid additives.
Seal Hardness: 92 ± 5 Shore A (Polyurethane), 75 ± 5 Shore A (Fluorocarbon).
Friction Coefficient: < 0.22 (optimized for smooth bucket tilt/pitch movement).
Fluid Compatibility: Compatible with standard anti-wear hydraulic oils (ISO VG 46, VG 68), as well as fire-resistant and synthetic types.
Secure Equipment & Depressurize: Fully lower the bucket to the ground to relieve hydraulic pressure. Disconnect and safely cap all hydraulic lines.
Ultra-Clean Workspace: Rebuild must be performed in a spotlessly clean, lint-free area. Contaminants are the leading cause of premature seal failure.
Thorough Inspection: Carefully examine the cylinder tube interior, piston rod surface, and gland housing for scratches, pitting, or ovality. Polish minor defects; replace the component if wear exceeds service limits.
Proper Seal Handling: Soak lip seals in clean hydraulic fluid before installation. Use installation cones or protective tape over rod threads to prevent cutting seal lips. Ensure all seals are seated squarely in their grooves.
Correct Assembly Order: Follow the included schematic. Pay special attention to the orientation of asymmetric seals like U-cups and wipers.
Post-Installation Procedure: After reassembly, bleed air by slowly cycling the cylinder several times. Check for leaks at operating pressure before resuming full work cycles.
Frequently Asked QuestionsWhat cylinders does this kit service on a wheel loader?
This kit is designed for the front-end loader linkage cylinders on Komatsu wheel loaders, specifically:
Bucket dump cylinder – Controls bucket curl and dump functions
Bucket pitch cylinder – Works in tandem with the dump cylinder on certain loader configurations to maintain bucket angle during boom movement (often part of the Z-bar linkage or parallel lift system)
The exact cylinder application depends on your loader's linkage design. On some models, dump and pitch cylinders may share identical seal specifications; on others, they differ. Always verify using the OEM cylinder number.
2. Which Komatsu wheel loader models is this kit confirmed for?
This kit is specifically cross-referenced for:
Komatsu WA380-3
Komatsu WA350-3A
It may also fit other WA-series loaders or Dash-3 generation machines with compatible cylinder dimensions, but fitment is guaranteed only for these two model designations. Other models, even within the WA series (e.g., WA380-5, WA380-6, WA350-5), likely use different cylinder part numbers and seal configurations.
3. Is this one kit per cylinder, or does it cover multiple cylinders?
Each kit services one hydraulic cylinder only. A typical wheel loader has:
Two dump cylinders (one on each side of the bucket)
One or two pitch/tilt cylinders (depending on linkage design)
To rebuild the complete bucket control circuit, you may need 3 to 4 individual kits — confirm your loader's cylinder count before ordering in quantity.
4. What is included in the kit?
This is a comprehensive kit containing all soft parts for a single cylinder overhaul:
Piston seal – High-pressure design for repeated dump cycle loading
Rod seal – Primary sealing element for the exposed rod
Buffer ring – Protects the rod seal from pressure transients during rapid bucket movements
Dust wiper / scraper – Heavy-duty exclusion seal critical for wheel loaders operating in dusty aggregate, quarry, or stockpile environments
Wear rings / guide bands – For both piston and rod gland, designed to absorb radial side-loading inherent in loader linkage geometry
Static O-rings and backup rings – For all gland, piston, and cylinder head sealing interfaces
5. What are the operating parameters?
Pressure rating: Up to 35 MPa (5,075 PSI) , standard for Komatsu Dash-3 loader implement circuits
Temperature range: -30°C to +110°C (-22°F to +230°F)
Seal material: Polyurethane for dynamic seals (high abrasion resistance for loader duty cycles), NBR for static O-rings, composite wear rings for side-load absorption
Fluid compatibility: Standard mineral hydraulic oils (ISO VG 32, 46, 68)
6. Why is the dust wiper especially critical for loader dump cylinders?
Wheel loader dump and pitch cylinders operate in some of the most contamination-intensive conditions of any hydraulic application. The rods are directly exposed to:
Fine aggregate dust (sand, crushed stone)
Cementitious particles (in concrete/construction environments)
Moisture and slurry splash (quarry and mining applications)
Frequent full-stroke cycling pumping contaminants past marginal wipers
COGENG's dust wiper uses an aggressive dual-lip profile with a secondary sealing edge specifically designed to scrape the rod clean before retraction. A compromised wiper is the leading cause of premature rod seal failure on loaders.
7. What are the common failure symptoms?
Bucket drift / droop – Bucket slowly uncurls under load or gravity, indicating piston seal bypass
External rod leakage – Oil visible on the chrome rod during operation, pooling on the cylinder body
Sluggish dump/curl response – Slow cycle times or reduced breakout force
Pitch function not maintaining angle – Linkage cannot hold preset bucket position during boom raise/lower
Contaminated hydraulic oil – Discolored or milky oil from external contaminant ingress
8. How do I confirm this kit fits my machine?
Before ordering, complete these verification steps:
Locate the OEM cylinder group number stamped on the barrel or gland (format: 707-XX-XXXXX) — this is the definitive identifier
Identify the cylinder's function — Dump (bucket curl), Pitch (linkage), or Boom Lift
Provide your loader's full model designation and serial number — WA380-3 and WA350-3A may have internal variants
Measure if stampings are unclear — Rod diameter and cylinder bore diameter are the minimum data points required for manual cross-reference
9. Is this a genuine Komatsu seal kit?
No. This is a COGENG aftermarket replacement engineered to match Komatsu OEM Part No. 707-99-64520 specifications. It delivers comparable performance and service life at a reduced cost versus genuine Komatsu components.
10. What special installation considerations apply to loader cylinders?
Loader dump and pitch cylinders experience extreme side-loading and high-frequency cycling. Critical installation requirements:
Cleanliness is paramount — any particulate introduced during rebuild will rapidly abrade new seals
Rod surface inspection — Chrome rods on loaders frequently suffer stone-chip damage; polish or replace any rod with pits or scratches before installing new seals
Torque compliance — Gland and piston nut torque values must match Komatsu shop manual specifications; the vibration environment of a loader will back off improperly torqued fasteners
Bleeding procedure — After rebuild, cycle the cylinder slowly through full stroke multiple times with the engine at idle to purge air before applying working loads
11. What is the shelf life?
Stored unopened at 5°C–30°C (41°F–86°F), in low humidity, and protected from sunlight and ozone sources, the kit has a shelf life of up to 7 years.
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