CAT 391-9892 BEARING-SLV-GD

CAT 391-9892 is a Caterpillar genuine YM series high-pressure pump plunger, compatible with high-pressure reciprocating pumps such as fuel injection pumps and hydraulic pumps. It is used for precise control of fluid volume and pressure, and is suitable for the fuel or hydraulic systems of excavators, loaders, bulldozers, and other equipment. It features high-pressure sealing, wear resistance, and fatigue resistance, making it suitable for the harsh operating conditions of construction machinery.

Core Technical Parameters

Item Details
Part Model CAT 391-9892 YM Pump Plunger (High-Pressure Reciprocating Plunger)

Material High-quality alloy steel (such as chromium-molybdenum steel) base material, surface nitrided/chrome-plated, hardness up to HRC 60-65, wear-resistant, high-pressure resistant, corrosion-resistant, suitable for high-pressure fuel/hydraulic oil environments

Key Dimensions Plunger diameter approximately 20-25mm, length approximately 80-100mm (subject to actual product and manual), clearance 0.001-0.003mm, ensuring high-pressure sealing and smooth reciprocating motion

Compatible Models Excavators 320D/330D, Loaders 950K/966K, Bulldozers D6/D7, Engines C9.3/C13, suitable for fuel injection pumps, hydraulic main pumps, pilot pumps, and other high-pressure pump bodies

Performance Characteristics High-precision external cylindrical grinding, surface roughness Ra≤0.05μm, reducing friction and leakage; nitriding / Chrome plating enhances wear resistance and corrosion resistance; suitable for high-pressure (up to 2000-3000 bar) conditions, ensuring stable flow and pressure.

Structure and Core Functions
Volume Compression and Fluid Delivery: Reciprocating motion within the pump cylinder, achieving fluid intake and discharge through volume changes, providing a high-pressure power source for engine fuel injection or hydraulic systems.

High-Pressure Sealing and Leakage Prevention: Precisely fitted with the plunger sleeve, relying on extremely small clearances to form an oil film seal with fuel/hydraulic oil, preventing high-pressure fluid leakage and ensuring pump volumetric efficiency and pressure stability.

Suitable for Precision Control: Works with injectors, overflow valves, and other components to precisely control fluid flow and pressure, adapting to the power requirements of different engine operating conditions or the operational precision of hydraulic actuators.

Installation and Maintenance Points
Installation Specifications
Clean the plunger and plunger sleeve, removing oil and impurities. Inspect the surface for scratches, rust, and dents to avoid accelerated wear or seal failure after installation.

Use specialized tools for assembly. Do not strike the plunger end face to prevent deformation or surface damage. Apply clean fuel/hydraulic oil for lubrication before installation to ensure smooth reciprocating motion.

Check the clearance to ensure it is within the range of 0.001-0.003mm. Excessive clearance can lead to leakage, while insufficient clearance can cause jamming.

Maintenance Recommendations: Every 2000-2500 working hours, check the plunger surface for wear, corrosion, and scratches, and whether the clearance exceeds the limit. Replace immediately if any abnormalities are found.

Replace the fuel/hydraulic oil filter element regularly to prevent impurities from entering the pump body and damaging the plunger and plunger sleeve.

Store in a sealed, moisture-proof environment to prevent surface rust from affecting the fit accuracy and sealing performance.