Part Number: 707-99-74210
PTC Number: PTE-74210
Genuine aftermarket Komatsu Service Kit (Part No: 707-99-74210). OEM-specification replacement compatible with Komatsu Dozer D155Ax 6 D155Ax 6A D155A 6 D155A 6R. Stocked in Mumbai for same-day dispatch across India. WhatsApp +91-98210-37990 for pricing.
Why seals are critical — and often underestimated: Hydraulic cylinder seals, O-rings, backup rings, and dust wipers are low-cost parts that prevent multi-thousand-rupee failures. A leaking boom or stick cylinder seal wastes hydraulic oil, reduces operating pressure, and — if left unattended — allows cylinder rod scoring that makes the entire barrel unserviceable.
Seal failure modes: Hard or brittle seals indicate heat damage (oil overheating above 90°C or fire proximity). Swollen or tacky seals indicate chemical incompatibility — usually mixing incompatible hydraulic fluid types. Lip cuts indicate rod scoring or improper installation with sharp edges. Side-loaded wear indicates cylinder misalignment.
Seal kit contents: A complete cylinder seal kit typically includes: piston seal (energized), rod seal, backup rings, O-rings, dust wiper, and wear rings. Always replace the complete kit — reusing old seals alongside new ones causes premature failure at the old seal's weak point.
Installation guidance: Ensure the cylinder rod is polished (Ra ≤ 0.4 µm) before installing new seals. Use only clean hydraulic oil or seal grease for lubrication during assembly — never petroleum jelly or grease which can swell NBR rubber. Inspect piston bore for corrosion or scoring before fitting new seals.
| Brand | Komatsu |
| Category | Spare Parts |
| Application | Komatsu Dozer D155Ax 6 D155Ax 6A D155A 6 D155A 6R |
This part (707-99-74210) is compatible with: Komatsu Dozer D155Ax 6 D155Ax 6A D155A 6 D155A 6R. NBR (nitrile) seals are standard for hydraulic oil applications and cover most heavy equipment use. FKM (Viton) seals are required for high-temperature or aggressive fluid environments (above 100°C continuous). PTFE backup rings are used in high-pressure applications. If replacing OEM seals, match the material specification.
Always replace the complete seal kit when overhauling a cylinder or assembly. Replacing individual seals alongside worn originals is false economy — the old seal will fail at its weakest point shortly after, requiring another teardown. Seal kits are designed to restore the entire sealing surface to new condition.
Primary causes of early seal failure: rod surface damage (scoring above Ra 0.4 µm), contaminated hydraulic oil, incorrect seal installation (installation damage from sharp edges), wrong seal material for the fluid type, and operating over the maximum system pressure. Fix the root cause before fitting new seals.
Provide: machine model and serial number, component name (e.g., 'boom cylinder'), and the cylinder bore and rod diameter if available. Seal kits are often available by machine and component (e.g., 'PC300-7 boom cylinder seal kit') or by part number. WhatsApp us a photo of your existing seals for faster identification.
Seal kits are supplied in sealed anti-static packaging. Store in a cool, dry location away from direct sunlight and ozone sources (electric motors) — these degrade rubber compounds. Do not stretch or fold seals during storage. Shelf life for properly stored seals is typically 5–10 years from manufacture date.
Pan-India Delivery
Dispatched within 1–2 business days from Mumbai. Delivery to your city in 3–5 days.
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