155-5109 CAT Hydraulic Piston Pump for 416C 428C Backhoe Loader

Product Overview

Technical Specifications

• Cross Reference Part Numbers: 155-5109, 185-5918, 155-6657, 1555109, 1855918, 1556657 (Caterpillar OEM replacement)
• Pump Type: Variable displacement swash-plate axial piston pump, open circuit with closed-center system
• Geometric Displacement: 74 mL/r
• Rated Continuous Working Pressure: 250 bar (aligned with original system relief setting)
• Peak Intermittent Working Pressure: 320 bar
• Rated Operating Speed: 2200 rpm (matched to engine rated output speed)
• Maximum Allowable Speed: 2400 rpm
• Rated Flow: 162.8 L/min (@2200 rpm, at full displacement)
• Control Mode: Load Sensing + Pressure Compensation control
• Shaft Extension: Standard spline shaft, matching original power input interface
• Mounting Flange: Original standard 4-bolt mounting flange for full direct interchangeability
• Housing Material: One-piece high-strength gray cast iron
• Reference Weight: Approx. 40 kg
• Compatible Fluid: ISO VG46 high-quality anti-wear hydraulic oil
• Operating Oil Temperature Range: -20℃ to 90℃
• Compatible Machines: Caterpillar 416C, 426C, 428C, 436C Backhoe Loaders

Key Technical Advantages

1. Micron-level Precision Machining & 100% Direct Damage-free Interchangeability

   Core friction pairs including cylinder bore, valve plate and slipper are processed with CNC honing and super-finish grinding, with dimensional tolerance controlled at micron level. The mounting flange, shaft parameters and port positions fully replicate original drawing standards, enabling direct replacement of original Caterpillar hydraulic pumps without modifying mounting brackets, connecting pipelines or control oil circuits, greatly reducing maintenance labor and retrofitting costs.

2. Load Sensing Variable Control for Energy Saving and High Efficiency

   The dual variable mechanism of load sensing and pressure compensation precisely adjusts displacement and pressure according to the real-time load demand of actuators, outputting hydraulic power on demand and eliminating energy loss and oil temperature rise caused by unnecessary overflow. Compared with fixed displacement pump systems, it reduces hydraulic energy consumption by more than 15%, effectively improving overall fuel economy and adapting to long-time continuous operation scenarios.

3. Heavy-Duty Material Configuration for Impact Resistance and Long Service Life

   The drive shaft is made of high-strength alloy structural steel with carburizing and quenching treatment, reaching surface hardness of HRC58-62 with excellent torsion and impact resistance. The valve pair adopts a high-strength cast iron and copper alloy matching scheme with outstanding wear resistance, withstanding frequent pressure shocks during digging operations. Paired with heavy-duty rolling bearings, it effectively prolongs the service life of the pump in dusty, high-vibration construction sites.

4. Full Working Condition Factory Testing for Stable and Reliable Performance

   Each pump passes 100% simulated bench test before delivery, covering multiple inspection items such as rated pressure holding, peak pressure shock, high and low speed cycle, oil temperature rise verification and internal leakage detection. The one-piece high-strength cast iron housing delivers strong vibration and impact resistance, operating stably within a wide temperature range of -20℃ to 90℃, adapting to complex field working environments and reducing on-site failure risks.

5. Optimized Flow Channel Low-noise Design for Improved Operating Experience

   The internal oil channel is optimized by computational fluid dynamics design to reduce hydraulic shock and cavitation noise. The kidney-shaped groove of the valve plate adopts a buffer damping structure to reduce pressure pulsation during high-low pressure chamber switching, controlling operating noise below 82dB. It also has a built-in pressure overload buffer mechanism to absorb instantaneous system pressure shocks and protect the pump body and downstream hydraulic valve blocks and cylinders.

Application Areas

• Municipal engineering: Hydraulic power systems for backhoe loaders in road construction, pipeline excavation, site grading, emergency repair and other operations
• Infrastructure construction: Earthmoving equipment for housing construction, earthwork projects, river dredging and other scenarios
• Agricultural infrastructure: Small construction equipment for farmland water conservancy, land consolidation and rural road construction
• Ports and yards: Engineering vehicles for cargo handling, equipment maintenance and bulk cargo transfer
• Mining auxiliary: Auxiliary operation equipment for site cleaning, material transfer and slope trimming in open-pit mines

Expert Maintenance Tips

1. Installation Calibration and Air Exhaust Specifications

   Ensure the coaxiality error between the pump shaft and engine power output shaft is ≤0.1mm during installation, to avoid premature wear of shaft seal and bearing caused by excessive radial force. Thoroughly clean the ports and connecting flange surface before installation, and prevent impurities such as iron filings and dust from entering the pump body. Fill the pump housing with clean hydraulic oil and exhaust internal air through the housing exhaust port before first startup to avoid dry friction damage to the valve pair and slippers.

2. Hydraulic Oil and Cleanliness Requirements

   Use high-quality anti-wear hydraulic oil compliant with ISO VG46 standard, with oil cleanliness reaching NAS grade 8 or above. The system return filter accuracy shall not be lower than 10μm. Ensure the suction pipeline is perfectly sealed to avoid air intake and cavitation, which would cause early pitting of valve plate and cylinder block. Normal operating oil temperature should be controlled between 30℃ and 70℃; long-term operation above 90℃ will accelerate seal aging and oil deterioration, and a cooling device is required for high-temperature working conditions.

3. Regular Maintenance Interval

   Check oil level and cleanliness every 500 working hours, inspect pipeline leakage and loose connections, and clean the suction filter. Replace hydraulic oil and return filter every 2000 working hours, and clean tank bottom deposits at the same time. It is recommended to disassemble and inspect the wear condition of internal friction pairs, check bearing clearance and variable spool flexibility every 4000 working hours to predict failure risks in advance.

4. Common Troubleshooting Key Points

   If output pressure is insufficient, first check whether the suction filter is clogged or the system relief valve setting is too low, then inspect whether the load sensing control spool is stuck or the valve pair is worn. If abnormal noise and vibration occur, focus on checking whether oil is aerated, bearing is worn, or installation coaxiality exceeds the standard. Do not operate the pump with oil shortage or air intake for a long time, to avoid irreversible damage to the pump body.