| Parameter | Specification / Value |
|---|---|
| COGENG Part Number | CGK-707-99-40040 |
| Replaces OEM Number | 707-99-40040 (Komatsu) |
| Primary Seal Material | Hydrogenated Nitrile Rubber (HNBR) & Polyurethane (PU) |
| Operating Temperature | -40°C to +110°C (-40°F to +230°F) |
| Maximum Pressure Rating | 40 MPa (5,800 psi) |
| Fluid Compatibility | Petroleum-based Hydraulic Oils (ISO VG 46, 68), HFA/HFB Fluids, Water Glycol |
| Shelf Life | 4 years from date of manufacture in original, unopened packaging. |
| Component Name | Material | Quantity | Key Function & Characteristic |
|---|---|---|---|
| Piston Seal (U-Cup) | Polyurethane (PU) | 1 | Main dynamic seal; excellent wear resistance and low friction. |
| Rod Seal (Lip Seal) | HNBR with reinforced heel | 1 | Primary rod sealing; retains fluid, handles high surface speeds. |
| Buffer / Secondary Rod Seal | HNBR | 1 | Protects primary rod seal from pressure pulses and extrusion. |
| Wiper / Scraper | Polyurethane (PU) | 1 | Rigid dual-lip design; effectively excludes dirt, mud, and moisture. |
| Piston Guide Ring (Wear Band) | Filled PTFE | 2 | Supports piston, absorbs side loads, prevents metal contact. Low coefficient of friction. |
| Rod Guide Ring (Wear Band) | Filled PTFE | 1 | Supports and centralizes the rod for smooth, even movement. |
| O-Rings (Various Sizes) | Nitrile (NBR) | As per diagram | Provide static sealing between gland, end caps, and other components. |
| Anti-Extrusion Rings | Rigid Thermoplastic | As required | Positioned behind primary seals to prevent gap extrusion under high pressure. |
This seal kit is designed for specific cylinder applications on the following Komatsu excavator models. Always confirm the cylinder part number or location before purchase.
| Model Series | Specific Models | Typical Cylinder Application |
|---|---|---|
| PC200/220 LC | PC200LC-6, PC200LC-7, PC200LC-8, PC220LC-6, PC220LC-7 | Swing Motor (Travel Motor on some variants) |
| PC228US | PC228US-3 | Swing Motor / Travel Motor |
| PC300/350 LC | PC300LC-6, PC300LC-7, PC350LC-6, PC350LC-8 | Travel Motor (Final Drive) |
| PC400 LC | PC400LC-6, PC400LC-7 | Auxiliary Cylinder (e.g., Hammer Circuit) |
| Dash-6 & Dash-7 Generations | Various models from the 200-400 size class | Specific hydraulic motors and auxiliary cylinders. |
System Preparation: Fully relieve all hydraulic pressure. Lower the work equipment to the ground and shut down the engine. Operate control levers to dissipate residual pressure.
Workspace & Cleanliness: Disassemble the cylinder or motor in a meticulously clean area. Contamination is the leading cause of premature seal failure.
Disassembly Care: Use appropriate tools. Note the order and orientation of all components during removal. Protect the highly polished cylinder rod and tube surfaces from scratches or nicks.
Critical Inspection: Measure the cylinder rod for scoring or wear. Inspect the tube bore and gland housing for pitting or grooves. Even new seals will fail quickly if installed on damaged hardware.
Seat & Groove Preparation: Clean all seal grooves with a non-metallic tool and solvent. Remove all old seal material, debris, and burrs. Ensure grooves are smooth and undamaged.
Correct Installation: Follow the provided kit diagram precisely. Lubricate all seals with clean hydraulic oil before installation. Use protective tape over threads and sharp edges. Install seals evenly without twisting, using a proper seal driver tool if needed.
Initial Operation: After reassembly, slowly cycle the cylinder or motor with the hydraulic lines slightly loosened to allow air to escape ("bleeding"). Tighten connections, check fluid levels, and monitor for leaks during initial low-pressure operation.
Q1: Which Komatsu excavator models use the 707-99-40040 hydraulic cylinder seal kit?
A: This seal kit is designed for specific Komatsu excavator hydraulic cylinders requiring OEM part number 707-99-40040. Please verify compatibility with your machine model and cylinder part number before ordering.
Q2: Is this an OEM or aftermarket seal kit?
A: It is an OEM-grade replacement kit, manufactured to meet or exceed original Komatsu quality standards for sealing performance, durability, and precise fit.
Q3: What is included in the Komatsu 707-99-40040 seal kit?
A: The kit includes all necessary rod seals, piston seals, wipers, O-rings, and backup rings for a complete hydraulic cylinder rebuild – no missing components.
Q4: What types of cylinders is this seal kit compatible with?
A: This kit is typically used for boom, arm, or bucket cylinders on Komatsu excavators. Confirm your specific cylinder application with your machine serial number.
Q5: How do I purchase the Komatsu 707-99-40040 hydraulic cylinder seal kit?
A: Contact us with your Komatsu machine model and cylinder details for fitment verification, then order directly through our website or sales team for fast shipping.
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