172122-73100 Main Hydraulic Pump for Yanmar YB251 YB301 Mini Excavator (Point-by-Point Layout)
1. OEM Part Number & Machine Compatibility
Yanmar OEM part number: 172122-73100
Original pump structure: Variable displacement axial piston pump integrated with built-in pilot gear pump assembly
Direct fit mini excavator models: Yanmar YB251, Yanmar YB301
Unified mounting flange, shaft spline and hydraulic port layout for direct replacement on both two machine models
2. Core Technical Specifications
Structure: Combined unit of variable main piston pump and integrated pilot charge gear pump
Matched displacement and internal flow parameters follow original factory hydraulic design for YB251/YB301 platform
Rated continuous working pressure conforms to original system setting, with preset maximum relief pressure for overload protection
Rotation speed range perfectly matched to the original 3TN78L engine equipped on these excavators
Input shaft spline size, installation bolt hole positions and port orientation strictly comply with OEM dimensional standards
Pump housing made of ductile iron; internal pistons, valve plates and wear parts adopt quenched alloy steel for wear resistance and long service life
3. Structure & Functional Description
Main piston pump outputs high-pressure hydraulic oil to drive boom, arm, bucket, left/right travel and swing movements
Built-in pilot gear pump supplies stable pressure oil for pilot control circuit and system oil replenishment
Internal power regulating valve automatically adjusts pump output flow according to actual load variation, preventing engine stalling under heavy digging conditions
Compact integrated structure saves installation space inside the narrow hydraulic compartment of old-generation small excavators
4. Product Core Advantages
Exact 1:1 OEM external casting dimension, plug-and-play installation without modifying hydraulic pipelines or machine mounting structure
Every finished pump undergoes full hydraulic bench testing for pressure stability, flow consistency and internal leakage inspection before delivery
Complete overhaul spare parts are available in stock, including seal kits, piston assemblies, swash plates, valve plates and pilot gear pump components for separate maintenance replacement
Single part number covers two excavator models, simplifying spare part inventory management for repair workshops and dealers
5. Packaging & Global Delivery Details
Input shaft and all hydraulic oil ports coated with anti-rust grease and sealed with protective dust plugs
Whole pump wrapped with moisture-proof plastic film and fixed inside export-grade solid wooden crate to avoid collision and damp damage during long-distance sea or air transportation
In-stock items can be dispatched within 3 to 5 working days after order confirmation
Multiple global shipping solutions available: international air express, sea LCL/FCL bulk shipment and overland truck transportation for Southeast Asian markets
6. FAQ
Q: Can this pump work for both Yanmar YB251 and YB301 directly?A: Yes, part number 172122-73100 is specially engineered for these two models with identical installation dimensions and matched hydraulic parameters, ready for direct bolt-on replacement.
Q: Are individual repair spare parts available for this hydraulic pump?A: Matching full overhaul seal kits, piston shoe assemblies, valve plates, swash plates and standalone pilot gear pump spare parts are all available for partial overhaul and component replacement.
Q: Is this pump a direct OEM replacement for old original pumps on these two machines?A: Yes, it matches all original interface and hydraulic calibration requirements, no adjustment or modification needed during field installation.