312D 312D2 259-0814 311-9298 SBS80 Hydraulic Main Pump Assembly Compatible with CAT

1. Product Overview & Wholesale Price Advantage

The CAT 312D / 312D2 SBS80 Hydraulic Main Pump Assembly (OEM Part # 259-0814 / 311-9298 / 10R-8657 / SBS80) is an advanced dual axial piston variable displacement pump engineered for 12-to-14-ton excavators operating under high-load excavation, slope clearing, and trenching works.

• Direct Factory Wholesale Price: $1,950 – $3,350 USD (Direct Source Supply — Save 50%–65% vs Regional OEM Dealer Markups)
• Zero Middleman Markup: Shipped straight from our manufacturing floor with zero distributor extra fees
• MOQ & Bulk Tier Discount: 1 Unit (Tiered volume wholesale discounts available for international equipment fleets & repair dealers)
• Lead Time: 1–3 business days (Large factory stock ready for immediate air/sea shipping)
• Quality Guarantee: 12 Months full replacement factory warranty with 100% dynamic 350 Bar bench test video proof

2. Application Worksite Checklist (施工场景清单)

Precision-matched flow control designed to deliver smooth hydraulic power under continuous field operations:

• Urban Utility Trenching & Pipe Laying: Fine hydraulic metering for smooth boom and arm excavation in narrow municipal ditches with CAT 312D excavators.
• Road Infrastructure Work: Sustained hydraulic working pressure under 350 Bar for rapid bucket loading cycles on CAT 312D2 machines.
• Agricultural Land Clearing: Thermal-resistant seal groups prevent internal oil bypass during long continuous operating hours in hot climates.
• Demolition Operations: Heavy cast iron pump housing built to absorb continuous high hydraulic pressure shockwaves from breaker attachments.

3. Hydraulic Main Pump Troubleshooting & Diagnostic Guide (液压泵常见故障排查)

If your CAT 312D excavator is exhibiting hydraulic system power loss, consult the diagnostic guide below:

• Fault 1: Cold Machine Operates Normally, But Machine Slows Down & Drops Pressure After 1 Hour (冷车正常,热车掉压发慢)
  Root Cause: Thermal expansion wear gap between the piston shoes, cylinder block, and valve plate inside the SBS80 rotary group.
  Solution: Replace with a complete drop-in CAT 312D main pump assembly (OEM 259-0814) or overhaul internal rotary group kit.
• Fault 2: Engine Stalls or Overloads When Actuating Hydraulic Boom/Arm (憋车/发动机过载熄火)
  Root Cause: SBS80 pump regulator power-control spool jammed or hydraulic pilot regulator valve miscalibrated.
  Solution: Recalibrate pump regulator pilot pressure or replace complete regulator valve assembly.
• Fault 3: Hydraulic Oil Leakage From Main Drive Shaft Seal Area (主驱动轴封高压串油漏油)
  Root Cause: Clogged casing drain line causing excessive internal pump housing backpressure, blowing out front drive shaft seal.
  Solution: Flush housing drain lines, replace front drive shaft seal, and check gear pilot pump relief pressure.
• Fault 4: Abnormal Cavitation Noise or Severe Vibration From Main Pump (泵体异响抖动/气蚀)
  Root Cause: Air suction at inlet pipe, contaminated hydraulic tank filter, or worn drive shaft roller bearings.
  Solution: Replace suction line seals, flush hydraulic fluid tank, and replace drive shaft roller bearings.
• Fault 5: Black Metallic Filings Found Inside Hydraulic Tank Filter (油箱内有黑粉或金属屑)
  Root Cause: Severe friction galling on swashplate shoe bronze layer or cylinder block face failure.
  Solution: Flush entire hydraulic piping system, clean main control valve, and install a new CAT 312D main pump assembly.

4. Hot Machinery Replacement Parts Recommendation (5大品类热门推荐表)

Explore our factory-direct replacement hydraulic components compatible with major global excavator brands:

5. Frequently Asked Questions & Technical Support (QA 问答专区)

Q1: How do I verify if this SBS80 main pump fits my CAT 312D or 312D2 excavator?
A: Check your original pump nameplate for OEM part numbers 259-0814, 311-9298, or SBS80 stamp. You can also send us your machine serial number for instant fitment verification.

Q2: My CAT 312D excavator slows down after 1 hour of digging. Will replacing the pump solve this?
A: Yes, thermal slowdown is caused by internal pressure leakage inside the worn pump cylinder block. Installing our new SBS80 main pump restores full hydraulic speed and digging power.

Q3: Is this CAT 312D hydraulic main pump bench tested before shipment?
A: Yes, every single pump undergoes a 5-step factory bench pressure test up to 350 Bar and volumetric efficiency check above 95%. A live test video is provided before shipping.