| Parameter | Specification |
|---|---|
| Product Name | Komatsu Hydraulic Cylinder Seal Kit / Complete Cylinder Overhaul Seal Set |
| Primary Part Number | 707-98-22120 (7079822120) |
| Brand | COGENG (Premium Aftermarket Replacement) |
| Condition | Brand New, 100% Dimensionally Inspected and Material Verified |
| Kit Type | Complete Hydraulic Cylinder Overhaul Seal Kit — Contains All Seals Required for Full Cylinder Reseal |
| Compatible Equipment | Komatsu PC200-7, PC200LC-7, PC210-7, PC220-7 Hydraulic Excavators |
| Seal Material | Nitrile Butadiene Rubber (NBR), Polyurethane (PU), Polytetrafluoroethylene (PTFE), Fluorocarbon (FKM/Viton) — Application-Specific |
| Backup Ring Material | Glass-Filled Nylon, PTFE, POM (Acetal) |
| Dust Seal Material | Polyurethane (PU) with Double-Lip Design for Superior Contamination Exclusion |
| O-Ring Material | NBR (Nitrile) 90 Shore A Durometer — High Pressure Resistant |
| Wear Ring / Guide Ring Material | Glass-Filled Nylon or Phenolic Resin Composite |
| Operating Temperature Range | -30°C to +110°C (NBR/PU); -20°C to +200°C (FKM Components) |
| Maximum Working Pressure | 35 MPa (350 bar / 5,000 psi) Rated |
| Hydraulic Fluid Compatibility | Mineral-Based Hydraulic Oil, Synthetic Hydraulic Oil, Water-Glycol Fire-Resistant Fluids (Per Seal Material Specification) |
| Quality Assurance | 100% Dimensional Inspection Against OEM Specifications; Material Hardness Verification (Shore A / Shore D); Tensile Strength Testing; Visual Inspection Under 10x Magnification |
| Certification | ISO 9001 Certified Manufacturing Facility |
| Place of Origin | Guangdong, China |
| Supply Capacity | 500 Pieces per Month |
| Shipping Weight | 0.5 – 1.5 kg (Gross, Kit Dependent) |
| Package Dimensions | 20 x 15 x 10 cm (Individual Box) |
| Packing | Inner: Anti-Static PP Bag with Desiccant; Outer: Heavy-Duty Export-Grade Corrugated Carton Box with Custom-Cut Protective Foam Insert |
| Payment Terms | Western Union, L/C (Letter of Credit), T/T (Telegraphic Transfer), MoneyGram, D/A (Documents against Acceptance), D/P (Documents against Payment) |
| Shipping Mode | By Air, By Sea, By Express (FedEx, UPS, DHL, TNT, etc.) — Optimized Based on Cargo Situation and Destination |
| Minimum Order Quantity | Acceptable Trial Order — Single Unit Orders Welcome |
| Return Policy | Non-Returnable / Non-Exchangeable (Comprehensive DOA Guarantee Included) |
The COGENG Hydraulic Cylinder Seal Kit, part number 707-98-22120 (7079822120), is a comprehensive, precision-manufactured overhaul seal set engineered as a direct, form-fit-function replacement for the hydraulic cylinder seals on the Komatsu PC200-7, PC200LC-7, PC210-7, and PC220-7 hydraulic excavator platforms. This seal kit contains every sealing component required to completely overhaul and reseal the machine's hydraulic cylinders—boom cylinders, arm cylinders, and bucket cylinders—restoring them to leak-free, factory-specification performance. The PC200-7 and its variants represent one of the most widely deployed 20-ton class excavator platforms in the world, machines that operate continuously in the most demanding construction, quarry, demolition, and infrastructure applications. The hydraulic cylinders on these machines are subjected to extreme internal pressures, continuous reciprocating motion, heavy side loads, and constant exposure to abrasive dust, mud, and moisture. The integrity of the cylinder seals is absolutely critical to machine performance and reliability.
A hydraulic cylinder seal kit functions as the complete internal sealing system of the cylinder assembly. The primary sealing components include: the piston seal, a high-pressure dynamic seal that rides on the cylinder bore and separates the high-pressure side of the piston from the low-pressure side, preventing hydraulic fluid from bypassing the piston and causing cylinder drift or power loss; the rod seal, a dynamic seal that rides on the chrome-plated cylinder rod and prevents pressurized hydraulic fluid from leaking out of the cylinder head during extension and retraction; the buffer seal, a secondary dynamic seal located ahead of the rod seal that absorbs pressure spikes and protects the rod seal from shock loads; the dust seal or wiper seal, the outermost seal that wipes dirt, dust, and moisture from the rod surface as it retracts, preventing contamination from entering the cylinder and damaging internal components; the O-rings and backup rings, which provide static sealing at the cylinder head, piston, and end cap interfaces and prevent extrusion of the primary seals under high pressure; and the wear rings and guide rings, which center the piston and rod within the cylinder bore, absorb side loads, and prevent metal-to-metal contact between moving components.
The operating environment for hydraulic cylinder seals on a PC200-7 excavator is exceptionally severe. The seals must withstand continuous internal pressures exceeding 30 MPa during heavy digging operations, with pressure spikes that can momentarily approach 40 MPa when a loaded bucket stalls or when the cylinder reaches the end of its stroke. The rod seal and dust seal are directly exposed to the external environment, subjected to abrasive dust, mud, water, and the chemicals used in machine washing. The seals must maintain their elasticity, hardness, and dimensional stability across a wide temperature range, from cold morning startups in winter conditions to sustained operating temperatures exceeding 100°C during heavy summer work. The primary failure modes of OEM seals are predictable: material degradation from thermal aging, compression set that causes the seal lip to lose contact with the sealing surface, abrasion and wear from contaminated hydraulic oil, extrusion damage at the seal groove corners under high pressure, and physical damage to the rod seal and dust seal from contaminated or damaged cylinder rods. COGENG's 707-98-22120 seal kit is manufactured using premium sealing materials selected for each specific application: high-performance polyurethane for the rod seal and dust seal, offering exceptional abrasion resistance and low friction; nitrile rubber for O-rings and static seals, providing excellent oil resistance and elasticity; PTFE for buffer seals and backup rings, offering low friction and high extrusion resistance; and glass-filled nylon for wear rings, providing excellent side load capacity and dimensional stability. Every seal in the kit is dimensionally inspected against OEM specifications and material-tested for hardness and tensile strength before shipment.
The 707-98-22120 seal kit is validated for the following Komatsu hydraulic excavator models. Always provide your complete machine model and serial number for final compatibility verification.
| Brand | Model | Machine Class |
|---|---|---|
| Komatsu | PC200-7 | 20-Ton Hydraulic Excavator |
| Komatsu | PC200LC-7 | 20-Ton Hydraulic Excavator (Long Carriage) |
| Komatsu | PC210-7 | 21-Ton Hydraulic Excavator |
| Komatsu | PC220-7 | 22-Ton Hydraulic Excavator |
Each COGENG 707-98-22120 Seal Kit contains the following components:
Piston Seal Assembly: High-pressure dynamic seal for the piston, manufactured from high-performance polyurethane or PTFE with an NBR energizer. Provides leak-free sealing across the full pressure range.
Rod Seal Assembly: Dynamic seal for the cylinder rod, manufactured from high-performance polyurethane. Prevents hydraulic fluid leakage from the cylinder head during operation.
Buffer Seal: Secondary dynamic seal installed ahead of the rod seal to absorb pressure spikes and protect the rod seal from shock loads.
Dust Seal / Wiper Seal: Outermost seal with a double-lip design to wipe contamination from the rod surface and prevent ingress into the cylinder.
O-Rings (Complete Set): All O-rings required for static sealing at the cylinder head, piston, and end cap interfaces, manufactured from NBR 90 Shore A.
Backup Rings: Anti-extrusion rings manufactured from PTFE or glass-filled nylon to prevent seal extrusion at high pressure.
Wear Rings / Guide Rings: Centering rings manufactured from glass-filled nylon to absorb side loads and prevent metal-to-metal contact.
Anti-Static PP Bag and Export Carton: All components are sealed in an anti-static PP bag with desiccant and packed in a protective carton with foam insert.
Note: The following descriptions provide a detailed technical walkthrough of accompanying high-resolution product photographs.
Image 1: Complete Seal Kit — Component Overview
A high-resolution photograph showing all components of the 707-98-22120 seal kit laid out in an organized arrangement. The image displays each seal type—piston seal, rod seal, buffer seal, dust seal, O-rings, backup rings, and wear rings—clearly labeled for identification.
Image 2: Piston Seal — Profile Detail
A close-up macro photograph of the piston seal, showing its cross-sectional profile and the precision-molded sealing lip geometry. The image highlights the seal's sliding surface finish and the energizer element.
Image 3: Rod Seal and Buffer Seal — Profile Detail
A detailed image showing the rod seal and buffer seal profiles. The image reveals the precision-molded sealing edges and the backup geometry designed for high-pressure performance.
Image 4: Dust Seal — Lip Design
A macro photograph of the dust seal, showing the double-lip design with the primary wiper lip and secondary contamination exclusion lip.
Image 5: O-Rings and Backup Rings
A photograph showing the complete O-ring and backup ring set, displaying the precise dimensional consistency and smooth surface finish of each component.
Complete Kit Coverage: The 707-98-22120 seal kit is a complete cylinder overhaul kit. It contains all seals required for one hydraulic cylinder reseal. Verify which cylinder (boom, arm, or bucket) requires this specific kit before ordering. Some machines may use different seal kits for different cylinder functions.
Material Compatibility: The seals in this kit are manufactured from NBR, polyurethane, PTFE, and glass-filled nylon. These materials are fully compatible with mineral-based hydraulic oils, synthetic hydraulic oils, and water-glycol fire-resistant fluids. They are not compatible with phosphate ester fluids (Skydrol).
Cylinder Rod Inspection: Before installing the new seal kit, the cylinder rod must be thoroughly inspected for scratches, pitting, chrome peeling, or other surface damage. A damaged rod will rapidly destroy new seals. If rod damage is present, the rod must be repaired or replaced before installing the new seals.
Installation Cleanliness: Hydraulic cylinder seal installation requires a surgically clean work environment. Any dirt, dust, or debris introduced during seal installation will cause premature seal failure and potential cylinder damage.
Professional Installation Recommended: While experienced mechanics can perform cylinder resealing in the field, this work is best performed in a clean shop environment by a qualified hydraulic technician with the proper tools, including seal installation sleeves, o-ring picks, and torque wrenches.
Note: This is a summarized procedural guide. Always follow the Komatsu service manual for your specific model.
Step 1: Cylinder Removal and Disassembly
Remove the hydraulic cylinder from the machine. Secure it in a suitable work stand. Thoroughly clean the exterior. Drain the hydraulic oil. Using the appropriate tools, disassemble the cylinder: remove the end cap, extract the piston rod assembly, and remove the old seals and wear rings. Inspect all components for wear, scoring, or damage.
Step 2: Component Cleaning and Inspection
Thoroughly clean all cylinder components with clean solvent. Inspect the cylinder bore for scoring, scratches, or wear. Inspect the piston and cylinder head for damage. Inspect the rod for pitting, scratches, or chrome damage. Verify that all seal grooves are clean, undamaged, and free of burrs.
Step 3: New Seal Installation
Using the appropriate seal installation tools, carefully install the new seals from the COGENG kit. Install the piston seal, wear rings, and O-rings onto the piston. Install the rod seal, buffer seal, dust seal, and O-rings into the cylinder head. Use seal installation sleeves to prevent seal damage when installing seals over threads and sharp edges. Lubricate all seals with clean hydraulic oil or a compatible assembly lubricant.
Step 4: Cylinder Reassembly
Carefully insert the piston rod assembly into the cylinder barrel. Install the end cap and torque to OEM specifications. Verify that the rod moves smoothly through its full stroke without binding.
Step 5: Installation and Testing
Reinstall the cylinder onto the machine. Reconnect all hydraulic lines. Refill the hydraulic system. Start the engine and cycle the cylinder through its full stroke multiple times to purge air. Check for leaks at the rod seal and all static connections. Verify correct cylinder operation and no drift.
| Detail | Description |
|---|---|
| Shipping Methods | By Air: Cost-effective for medium-weight orders. By Sea: Most economical for bulk orders. By Express (FedEx, UPS, DHL, TNT): Fastest door-to-door service. The specific method is optimized based on cargo situation and destination. |
| Estimated Delivery Time | Express: 3-5 business days. Air Freight: 8-15 days. Sea Freight: 30-45 days. Transit times are carrier-dependent. Tracking provided within one business day of dispatch. |
| Packing | Inner: Anti-static PP bag with desiccant. Outer: Heavy-duty export-grade corrugated carton box with custom-cut protective foam. |
| Payment Terms | Western Union, L/C, T/T, MoneyGram, D/A, D/P. Standard terms: 30% T/T deposit, 70% balance before shipment. |
| Minimum Order Quantity | Acceptable Trial Order — Single unit orders welcomed. |
| Policy Point | Terms |
|---|---|
| Merchant Return Policy | All sales are final. No returns or exchanges. Seal kits are precision sealing components. Once departed from our controlled environment, we cannot verify they have not been installed, contaminated, or damaged. |
| DOA Quality Guarantee | Full replacement for manufacturing defects reported within 7 days of delivery. Kit must be in original, unopened condition. |
| Pre-Shipment Confirmation | We send high-resolution photos of your exact seal kit for written approval before dispatch. |
Q1: What are the symptoms of worn hydraulic cylinder seals?
A: Common symptoms include: hydraulic oil leaking from the cylinder rod area, cylinder drift where the implement slowly lowers or retracts under load, reduced digging force or lifting capacity, jerky or uneven cylinder movement, visible scoring on the cylinder rod, and excessive hydraulic oil consumption. Any of these symptoms indicate that cylinder resealing is required.
Q2: Does this kit service one cylinder or all cylinders?
A: This kit contains the seals required to overhaul one hydraulic cylinder. Each cylinder (boom, arm, bucket) requires its own seal kit. Verify the correct kit part number for the specific cylinder you are servicing.
Q3: What is the difference between NBR and polyurethane seals?
A: NBR (nitrile rubber) is used for O-rings and static seals due to its excellent oil resistance and elasticity. Polyurethane is used for dynamic seals (rod seals, dust seals) due to its superior abrasion resistance, high tensile strength, and low friction characteristics. The COGENG kit uses the correct material for each sealing application.
Q4: Can I install this seal kit myself?
A: Hydraulic cylinder resealing requires mechanical skill, the proper tools, and a clean work environment. While experienced mechanics can perform this work in the field, we recommend having the work performed by a qualified hydraulic technician in a clean shop environment to ensure maximum seal service life.
Q5: How long will these seals last?
A: Seal service life depends on operating conditions, hydraulic oil cleanliness, cylinder rod condition, and installation quality. With clean oil, an undamaged rod, and correct installation, these seals will provide service life equivalent to or exceeding OEM seals.
For pricing, machine-down emergency support, trial orders, bulk quantity discounts, or pre-purchase compatibility verification, contact your COGENG supplier today.
Sales Price: Contact COGENG sales customer service directly for the most current competitive pricing. Trial orders welcome.
Shipping Method & Cost: We will quote the optimal shipping solution based on your location and urgency.
Estimated Delivery Time: Based on the selected carrier. Tracking provided within one business day of dispatch.
✅ Direct OEM Replacement — Complete Cylinder Overhaul Kit for Guaranteed Leak-Free Performance.
✅ Komatsu PC200-7 Series Compatible — Validated for PC200-7, PC200LC-7, PC210-7, PC220-7.
✅ Premium Sealing Materials — Polyurethane, NBR, PTFE, and Glass-Filled Nylon for Maximum Service Life.
✅ ISO 9001 Certified — 100% Dimensional Inspection, Material Verified, 500 Kits Monthly Supply.
✅ Trial Orders Welcome — Single Unit Orders Accepted.
✅ In Stock & Ready to Ship — Minimize Excavator Downtime with Immediate Worldwide Dispatch.
Critical Action: To ensure 100% compatibility, please provide your Komatsu excavator's complete model and serial number, and identify which cylinder (boom, arm, bucket) you are servicing. Our technical team will verify the correct seal kit for your application.
Merchant Return Policy: All products shipped are not returnable or exchangeable. Please complete all compatibility checks before purchase.
