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| Parameter | Specification / Value |
|---|---|
| COGENG Part Number | CGK-8780-494OR |
| OEM Part Number | 878000494 (Komatsu) |
| Primary Seal Material | StaticLoad™ Hydrogenated Nitrile (HNBR) |
| Wiper & Scraper Material | Polyurethane (AU) - 90 Shore D |
| Temperature Range (Operational) | -40°C to +125°C (-40°F to +257°F) |
| Static Pressure Holding | 30 MPa (4,350 psi) continuous (72-hour rated) |
| Dynamic Pressure Rating | 25 MPa (3,625 psi) |
| Fluid Compatibility | Komatsu BIOHYDRO (Biodegradable), HFDU, HLP, ISO VG 46 |
| Compression Set (ASTM D395) | ≤ 9% (70 hrs @ 125°C) |
| Breakout Friction | Optimized for ≤ 0.08 static coefficient to prevent "stiction" |
| Component Name | Material & Specification | Qty | Critical Function for Outrigger Duty |
|---|---|---|---|
| Main Piston Seal | StaticLoad™ HNBR, Double-Acting Symmetric Lip | 1 | Seals pressure in both directions during minor load shifts; symmetrical design prevents rolling. |
| Primary Rod Seal | StaticLoad™ HNBR with Low-Friction PTFE Impregnation | 1 | Dynamic seal for retraction; PTFE reduces breakout force after long stationary periods. |
| Rod Scraper | Ultra-Hard PU (95 Shore D) with steel lock ring | 1 | Aggressively removes packed mud, ice, and debris before they contact the rod seal. |
| Rod Wiper | Soft-Lip PU (80 Shore A) bonded to scraper | Integrated | Secondary seal that retains a thin oil film on the rod for corrosion protection. |
| Piston Wear Band | Zinc-Nickel Plated Bronze, filled with graphite | 2 | Provides maximum load support for the piston; graphite filling aids lubrication if fluid film is lost. |
| Rod Wear Band | Rulon® J (PTFE Composite) with low-friction coating | 1 | Key Component: Virtually eliminates stick-slip, ensuring smooth outrigger retraction. |
| Static O-Rings (Port & Gland) | Fluoro-Viton® (FKM) | 4 | Superior resistance to weathering, ozone, and chemical exposure on exterior ports. |
| Cushion Seal (if applicable) | Standard NBR | 1 | For models with internal cushioning at the end of stroke. |
| Thread & Chrome Protector | Flocked Polyethylene | 1 | Soft, absorbent sleeve to protect the chrome rod during handling and installation. |
This kit is designed specifically for the outrigger (stabilizer) cylinders of the following model. Its design may also fit similar outrigger systems on related wheeled machines.
| Primary Machine Model | Machine Type | Cylinder Location & Function | Notes on Variants |
|---|---|---|---|
| Komatsu WB140-50 | Wheeled Excavator | Front & Rear Outrigger/Stabilizer Cylinders | Fits all outrigger cylinders on this model. |
| Komatsu WB140-5 | Wheeled Excavator | Likely compatible, but verification required | Early series may have slight dimensional differences. |
| WB130-5 / WB150-5 | Wheeled Excavators | Not directly compatible without verification. | Outrigger designs differ; do not use without cross-reference. |
Phase 1: Pre-Service Safety & Setup
Machine Stabilization: Engage ALL outriggers not being serviced. Use certified jack stands under the machine's main frame in addition to the outriggers to create a redundant safety support system. Never rely on hydraulic cylinders alone for support during repair.
Pressure Relief: After stabilizing the machine, slowly operate the outrigger control lever to the "lower" position with the engine OFF to relieve residual pressure in the lines. Then, manually crack the hydraulic fittings on the target cylinder to confirm pressure is bled off.
Phase 2: Disassembly & Inspection for Outrigger Specifics
3. External Contamination Management: Outrigger rods are heavily exposed. Before retraction, clean the exposed rod thoroughly. Upon disassembly, immediately cover the rod end with a protective cap to prevent dirt from entering the tube.
4. Corrosion Inspection: Pay special attention to the non-chrome portion of the rod that is inside the cylinder when retracted. This area is prone to pitting corrosion, which will destroy new seals. Light pitting can be polished smooth; severe pitting requires rod replacement.
5. Check for Bent Rod: Roll the rod on a flat surface. Any gap or wobble indicates a bend. A bent rod cannot be reliably sealed and poses a safety risk. Replace it.
Phase 3: Seal Installation (Outrigger-Specific Techniques)
6. Sequential Packing Installation (Gland):
a. Install the Rulon® rod wear band first. It should slide in smoothly by hand.
b. Install the primary rod seal. The PTFE-impregnated side faces the inside (oil side). Use a installation sleeve.
c. Press the combined Scraper/Wiper assembly into the gland bore until the steel lock ring positively clicks into place. Do not hammer directly on the PU material.
7. Piston Assembly: Install the bronze wear bands onto the piston. They should have a slight hand-press fit. Then, install the double-acting piston seal. Ensure it is not twisted in its groove.
8. Lubrication: Use a phosphate ester-compatible grease (e.g., Skydrol LD-4) to lubricate all seals during assembly if the machine uses biodegradable (BIOHYDRO) fluid. This prevents seal swelling during initial contact.
Phase 4: Reassembly, Bleeding & Function Test
9. Reassembly Care: When inserting the rod assembly into the tube, ensure the rod is perfectly aligned to avoid gouging the tube bore. Turn the rod slowly while inserting.
10. Air Bleeding Procedure: Outrigger cylinders can be difficult to bleed due to their horizontal orientation. After reconnection, fully extend the outrigger (foot on ground), then slightly loosen the rod-end port fitting. Retract the cylinder slowly. Tighten the fitting as fluid seeps out. Repeat 2-3 times until no air bubbles are seen.
11. Function & Load Test:
* Cycle the outrigger 3-5 times with no load (foot off ground).
* Then, lower it to ground and apply minimal down pressure. Hold for 5 minutes and inspect for leaks.
* Crucial Test: Observe the retraction phase. It should initiate smoothly without jerking ("stick-slip"). Any jerking indicates improper installation of the low-friction components.
Safety Warning: After service, always perform a full stability test by lifting the machine slightly off the ground with the outriggers before placing under full operational load.
