Hitachi ZAX670-3 / ZAX870-3 Pump Transfer Case Assembly – China Remanufactured (9276421)

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Between your engine and your main pumps sits a component that nobody thinks about – until the machine stops moving.

The Three Silent Killers of Your ZAX670-3 / ZAX870-3 Transfer Case

On a 70–80 ton excavator, the pump transfer case (OEM 9276421) is the mechanical hub that splits engine torque to drive both main hydraulic pumps. It runs in oil, sealed from the outside, and requires no daily attention. That is precisely why failures are always sudden – and always expensive.

Killer #1 – Bearing fatigue

Transfer case bearings spin at engine speed for tens of thousands of hours. Every revolution adds a tiny stress cycle. After 10,000–12,000 hours, even the best bearings develop micro‑cracks. The machine runs fine one day. The next day, a bearing cage lets go. The transfer case locks up, the pumps stop turning, and your excavator becomes a 70‑ton paperweight.

What we do: Every bearing in our remanufactured transfer case is replaced. Not inspected. Not “tested.” New. Always.

Killer #2 – Contaminated oil

The transfer case shares no oil with the hydraulic system, but it can still get contaminated. Moisture from condensation, dust past a failed vent, or debris from a worn gear will turn the oil into grinding paste. Once the oil loses its film strength, gears and bearings wear at ten times the normal rate.

What we do: The housing is hot‑tanked and flushed. Gears are inspected for pitting – any gear with spalling is replaced. You get a clean gearbox with fresh oil, not a cleaned‑up failure.

Killer #3 – Misalignment after pump or engine work

This is the most frustrating failure. A transfer case that was perfectly healthy fails within 200 hours of a pump replacement. The cause is almost always misalignment between the transfer case, engine flywheel housing, and main pumps. Even 0.5mm of offset will destroy bearings in weeks.

What we do: We cannot fix your installation – but we warn you. Every remanufactured transfer case ships with a bold‑print alignment guide. Follow it, and your transfer case will outlast the undercarriage.

What You Are Buying

A remanufactured 9276421 transfer case assembly, built to original Hitachi specifications for the ZAX670‑3 and ZAX870‑3.

• New bearings – every single one. No reused bearings.

• 全新密封件和O型圈 – high‑temperature fluororubber (FKM).

• Gears inspected and reconditioned – pitted gears replaced.

• Housing cleaned, crack‑inspected, and painted – like new.

• 发货前照片 – you see the actual unit before packing.

• 重型木箱包装 – fumigation‑free, export ready.

• 5–8个工作日交货 – from our Guangzhou warehouse.

Who Needs This Transfer Case

• 采矿承包商 – You cannot afford a bearing seizure on the face. A reman transfer case with new bearings eliminates the gamble.

• Fleet owners with multiple ZAX670‑3 / ZAX870‑3 – Standardize on reman units. Predictable cost, predictable life, predictable scheduling.

• Owners after a main pump failure – If your pump failed with debris, that debris went through the transfer case too. Do not skip it. Clean the transfer case or replace it.

• Anyone who has just replaced main pumps – Alignment is critical. A reman transfer case gives you a fresh start.

Installation – The One Page That Saves Your Machine

We include a printed alignment guide with every transfer case. Here is what it says:

1. Bolt the transfer case to the engine flywheel housing – do not force it. If the bolts do not slide in by hand, something is misaligned.

2. Check concentricity – use a dial indicator on the pump drive flange. Runout must be within 0.2mm. If it exceeds, shim or adjust.

3. Mount the main pumps – grease the splines lightly. Tighten bolts in a star pattern. Do not hammer the pump onto the spline.

4. Fill with correct oil – refer to your Hitachi service manual (typically heavy‑duty gear oil, API GL‑5, viscosity as specified). Do not overfill.

5. Run without load first – idle for 5 minutes, listen for unusual noise. If it sounds wrong, stop and recheck alignment.

The most common mistake: Assuming the old transfer case was aligned, so the new one will be too. Alignment changes when you remove and replace components. Check it every time.

为何选择鸿腾达配件

We have been remanufacturing Hitachi drivetrain components since 2001. The ZAX670‑3 and ZAX870‑3 are proven machines, but their transfer cases are now reaching the end of their natural life. New OEM units are expensive and often have long lead times. Used units are a gamble – you have no idea how many hours remain.

A remanufactured transfer case from HTD gives you new bearings, new seals, reconditioned gears, and a clean housing. You get the confidence of a fresh start without the new‑OEM price.

保修说明： 3‑6 months depending on product details. We do not provide warranty for original used or remanufactured parts. Our promise is in the work: new bearings, proper assembly, and pre‑shipment photos. For warranty‑covered options, ask about new aftermarket units.

Before You Order

请向我们提供：

• Your ZAX670‑3 or ZAX870‑3 machine serial number

• A photo of the old transfer case (or its nameplate)

We will confirm fitment and provide a quote within 24 hours.