COGENG 707-52-90300 7075290300 High-Pressure Hydraulic Cylinder Seal Kit

Technical Constants & Performance Data

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Exact Model Compatibility

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Component Specifications Table

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Specific Components Included

• Main Piston Seal (U-Cup) – Qty: 1

• Rod Seal (Step Seal) – Qty: 1

• Wiper/Scraper – Qty: 1

• Buffer Ring – Qty: 1

• Wear Ring (Piston) – Qty: 1

• Complete O-Ring & Backup Ring Set – Qty: 1 Set (All necessary sizes for gland and SAE port assembly)

• Note: This kit provides a complete seal profile set designed to match the exact specifications of the original Komatsu 707-52-90300 bucket cylinder kit. An exploded diagram is included for correct assembly.

Decompose pictures


Parts list



Installation decomposition diagram

1. Safe Depressurization & Support: Park the excavator on level ground. Lower the bucket fully to the ground to relieve all hydraulic pressure. Mechanically block the bucket or cylinder rod to prevent any movement.

2. Ultra-Clean Environment: Perform all work in a meticulously clean, dust-controlled area. Bucket cylinders are highly susceptible to abrasive contamination. Use a parts washer, clean solvent, and lint-free cloths.

3. Documented Disassembly: Carefully disassemble the cylinder gland. Photograph and label each component and its precise orientation. Note the exact stacking order of all seals and spacers in the gland.

4. Mandatory Metal Inspection: Use a micrometer to inspect the cylinder rod for scratches, pitting, or scoring. Inspect the cylinder bore (ID) for wear, tapering, or scoring. Damaged metal components must be replaced.

5. Proper Seal Installation: Soak all new elastomeric seals in clean hydraulic fluid. Use seal installation cones, sleeves, and nylon picks designed for large diameters. Never use sharp metal tools that can nick seals.

6. Precision Reassembly: Follow the included diagram exactly for seal order and orientation. Ensure each seal is fully and squarely seated in its groove before proceeding to the next.

7. Torque Specifications: Use a calibrated torque wrench. Adhere strictly to Komatsu's specified torque values and sequences for gland bolts or tie-rods. Use a criss-cross pattern for even flange compression.

Frequently Asked Questions
A. When will get the items after I place order?
Q. Once your payment is confirmed,we will arrange the goods within 1~4 days; if not in stock, we will inform you before placing the order?

A. If I only know the excavator model, but can not offer parts No.,what should I do ?
Q. If possible, you can send us pictures of old products, nameplate or the size for reference.

A. How can you guarantee the quality??
Q. We will 100% test the goods before delivery. We also support video inspection.

A. How long will it take to delivery to my address??
Q. The normal delivery time is 3-7 days, depending on which country you are in.?

A : Which delivery method will you choose?
Q : By sea, air or express(DHL,Fedex,TNT, UPS, EMS etc.)，Sometimes we will arrange as the customer's demand.

A: What's package? Can you give me the package according my requirement??
Q. We usually packed by standard exported box or carton. And yes we can pack as per your requirement.

A: Can the price be cheaper?
Q: Of course, you will be offered a good discount for a big amount.

A: Why should I choose to buy from you?
Q:Our advantages: 100% quality assurance, develop and manufature follow original ones;Quick response within 24 hours; Small order allowed;Reasonable stock and timely delivery;Neutral packing, customized packing are allowed. Positive customer feedback from abroad market;Excellent after-sales service.
A : Which payment terms can you accept?
Q : Paypal. Western Union, Bank Transfer, T/T...