155-5109 161-6634 Cat Hydraulic Piston Pump 416C 426C 436C 438C

Product Overview

The 155-5109 (interchangeable with 161-6634, 112-6564, 1555109, 1616634, 1126564 and others) is a high-precision, fully interchangeable main hydraulic axial piston pump designed for Caterpillar 416C, 426C, 436C and 438C backhoe loaders. As the core power source of the machine’s load-sensing closed-center hydraulic system, it delivers stable variable flow to support simultaneous loader and backhoe functions. Every unit undergoes 100% simulated operating condition testing to ensure exact dimensional, interface, drive and performance interchangeability with the original Caterpillar pump—enabling true drop-in replacement without any modification.

Technical Specifications

• Model: 155-5109 (Interchange numbers: 161-6634, 112-6564, 1555109, 1616634, 1126564, etc.)
• Compatible Machines: Caterpillar Backhoe Loader 416C, 426C, 436C, 438C
• Pump Type: Variable displacement axial piston (main hydraulic pump, load-sensing system)
• System Flow: approximately 43 gpm (162 L/min)
• System Pressure: approximately 207 bar (3000 psi)
• Hydraulic System Type: Load-sensing, closed-center
• Mounting & Interfaces: Exact match to OEM flange, shaft end and port locations
• Operating Characteristics: Supports loader bucket, backhoe arm, swing and steering circuits
• Interchangeability: Direct drop-in replacement, no plumbing or bracket modifications required
• Testing Standard: 100% simulated real-world duty cycle testing for pressure, flow and durability

Key Technical Advantages

1. Precise Drop-in Interchangeability: Mounting dimensions, shaft end and port locations are identical to the original, allowing true plug-and-play installation and eliminating field modification risks.
2. Load-Sensing Variable Control: Automatically adjusts flow and pressure according to system demand, improving energy efficiency and reducing heat generation under complex backhoe loader duty cycles.
3. High-Strength Materials and Precision Machining: Premium cast-iron housing and precision piston components provide excellent impact resistance and volumetric efficiency under frequent high-pressure shock loads.
4. Stable Output with Low Ripple: Optimized valve plate and piston design reduces pressure pulsation, minimizing system shock and extending the service life of valves and cylinders.
5. Rigorous Duty-Cycle Testing: Each pump is 100% tested under simulated load and temperature cycles to ensure long-term reliability in dusty, vibrating and high-duty environments.

Application Areas

• Main hydraulic system of Caterpillar 416C / 426C / 436C / 438C backhoe loaders
• Loader bucket, backhoe arm, swing and steering circuits
• Engineering machinery requiring stable high-pressure flow for combined operations
• OEM pump replacement or preventive maintenance upgrades

Expert Maintenance Tips

• Confirm machine model and serial number before installation; check shaft and flange alignment.
• After installation, fully bleed the system and inspect suction line seals to prevent cavitation-related early wear.
• Maintain hydraulic fluid cleanliness at ISO 4406 18/16/13 or better and replace return filters regularly.
• Avoid prolonged over-pressure operation; monitor system temperature and noise levels.
• After initial run-in, check for leaks and verify bolt torque; follow OEM seal replacement intervals.
• Keep ports sealed during storage to prevent contamination.