312D2 or 312E pump pressure declining or case drain overheating? A worn 391-9442 SBS80 main pump loses volumetric efficiency as rotating group clearances open, reducing all circuit flow simultaneously. RITO supplies this precision SBS80 pump assembly to restore full 312D2-series hydraulic system flow and pressure.
Item NO.:
391-9442Order(MOQ):
1pcsPayment:
T/T, WESTERN UNION, CHINESE BANK,PAYPALProduct Origin:
JAPANShipping Port:
Huangpu,GuangzhouLead Time：
In Stock391-9442 Hydraulic Main Pump Assembly for Caterpillar 312D2, 312D2 GC, 312D2L, 312E and 313D2 excavators. Cross-references: 3919442, 387-2606. SBS80 variable axial piston pump with factory-calibrated regulator for 312D2-series engine and LS circuit specification. New rotating group and matched valve plate restore rated displacement from first operation.
| Part Number | 391-9442 / 3919442 / 387-2606 |
|---|---|
| Part Name | Hydraulic Main Pump Assembly (SBS80) |
| Compatible Brand | Caterpillar |
| Applicable Models | 312D2, 312D2 GC, 312D2L, 312E, 313D2 Excavator |
| Application | SBS80 main variable axial piston pump for Caterpillar 312D2-series hydraulic system |
| Material | Precision alloy steel rotating group and pump housing |
| Product Color | Industrial finish |
| Working Temperature | -25°C~+60°C |
| Key Function | Generates main hydraulic system flow and pressure for Cat 312D2-series all-function operation |
| Condition | 100% New Aftermarket OEM Quality |
| Packaging | Wooden Case Reinforced Carton Neutral Packing Customized Box |
391-9442 cross-references to 3919442 and 387-2606 across 312D2 production ranges; all three numbers apply to the same SBS80 pump application.
Regulator pre-set to 312D2 LS differential specification, preventing the standby pressure hunting that occurs when generic SBS80 pumps are installed without 312D2-specific regulator calibration.
Power-limit spring pre-load set to 312D2 C4.4 engine torque curve, preventing engine overload under combined hydraulic load.
391-9442 covers 312D2, 312D2 GC, 312D2L, 312E and 313D2 - the full Cat 312 second-generation excavator range.
FAQ
Q: How do I confirm the 391-9442 pump is the source of 312D2 flow loss?
A: Test combined case-drain flow from both pump sections at rated speed and pressure. Both sections above OEM spec confirms rotating group wear. Isolated high drain from one section may indicate a valve or relief circuit fault.
Q: What is the difference between 391-9442 and 387-2606?
A: 387-2606 is a cross-reference for the 391-9442 SBS80 pump application on 312D2 and 313D2. Both refer to the same pump specification. Confirm your specific machine serial number range with our team if uncertain.
Q: Should I flush the 312D2 hydraulic circuit before fitting the new 391-9442?
A: Yes. Drain the tank, clean the interior, replace all filter elements, and run at low pressure for 30 minutes before applying full load. Debris from the old pump will score the new rotating group immediately if not removed.
Q: How to confirm 391-9442 is correct for my 312D2?
A: Match part number 391-9442, 3919442 or 387-2606. Confirm machine is 312D2, 312D2 GC, 312D2L, 312E or 313D2. Provide machine serial number for cross-reference.
Q: What quality options are available?
A: We provide original, OEM and high-quality aftermarket versions with stable supply capability.
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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