Rising oil temperature, metal particles in the swing housing oil or a machine that creeps and then stops are classic symptoms of a tired ZX870 Swing Reduction Gearbox. Once the bearing preload is lost the gear mesh runs out of alignment and wear accelerates quickly. RITO supplies this ZX870 Swing Reduction Gearbox as a complete unit for standard excavators, returning swing torque and swing speed to specification.
Item NO.:
ZX870Order(MOQ):
1pcsPayment:
T/T, WESTERN UNION, CHINESE BANK,PAYPALProduct Origin:
JAPANShipping Port:
Huangpu,GuangzhouLead Time：
In StockAs a complete ZX870 Swing Reduction Gearbox, this assembly covers everything behind the hydraulic motor: ring gear, planet gears, carriers, bearings, seals and output shaft. Using one matched assembly avoids the mismatch that comes from mixing new gears with worn carriers, which is the usual reason a rebuilt unit fails again within a few hundred hours. It fits the standard mounting of standard excavators and is supplied ready to install.
| Part Number | ZX870 |
| Part Name | Swing Reduction Gearbox |
| Compatible Brand | Hitachi |
| Applicable Models | ZX870 |
| Application | Excavator swing reduction unit in the upper structure swing circuit |
| Material | Cast iron housing with hardened alloy steel gear set |
| Product Color | Industrial grey / OEM color |
| Working Temperature | -25°C~+80°C |
| Key Function | Turns motor torque into controlled swing rotation |
| Condition | 100% New |
| Packaging | Wooden Case Reinforced Carton Neutral Packing Customized Box |
 | Tested Before Packing Each unit is checked for backlash, turning torque and seal integrity, then packed in a reinforced case to survive international freight. |
 | Complete Assembly Ring gear, planets, carriers, bearings, seals and output shaft arrive as one unit, so nothing is reused from a worn original. |
 | Matched Gear Set Ring gear and planet gears are lapped as a matched set, so tooth contact is full width from the first hour and the unit stays quiet under load. |
 | Factory Preload Bearings are shimmed and preloaded on the assembly line, which removes the end float that causes noise and premature wear in field rebuilds. |
Q: What usually causes these reduction units to fail?
A: Contaminated oil and lost bearing preload. Once dust enters through a worn seal, the bearings loosen, the gear mesh misaligns and the unit starts to whine and overheat within a few hundred hours.
Q: Do I need to adjust backlash after fitting?
A: No. Backlash and bearing preload are set at assembly. Fit the unit, fill with the specified oil grade, and check for leaks after the first few hours of operation.
Q: Is this a complete assembly or just the gear set?
A: It is supplied as a complete reduction assembly - housing, ring gear, planet gears, carriers, bearings, seals and output shaft - so nothing has to be transferred from the old unit.
Q: How do I confirm this ZX870 unit fits my machine?
A: Compare the mounting bolt pattern, the output spline and the overall height against the unit on your machine, and check the model plate. If the numbers differ, send us a photo of the plate and we will confirm the correct variant.
Q: Which oil should I use after installation?
A: Use the grade listed in the machine service manual for the final drive or swing reduction. Overfilling causes heat; underfilling causes immediate bearing damage, so fill to the level plug.
Q: Can this unit be used as an upgrade on an older machine?
A: Where the mounting pattern and spline match, the later specification can be fitted to earlier machines. Confirm the interface dimensions with us before ordering.
Q: Why Choose RITO?
A: Listed Factory
Stable&Reliable Quality
OEM Factory for Chinese Top Excavator Brands
Supplier to Fortune 500 Companies
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