PVD-1B-28P-8G3-5161A Nachi Split-Flow Piston Pump 34cc 24.5MPa

Product Overview

The PVD-1B-28P-8G3-5161A / PVD-1B-29BP-11G5-452 is a Nachi PVD-series dual split-flow axial piston pump engineered for 3–3.5 tonne class mini excavator hydraulic systems. Featuring a precision swash-plate design with two independent displacement chambers, it delivers equal synchronized flow to the left and right travel motors, ensuring excellent straight-line tracking. The unit offers 100% drop-in interchangeability with genuine Nachi pumps—no piping or mounting modifications required. Every unit undergoes full simulated operating-condition testing to guarantee high volumetric efficiency and reliability under high pressure and variable speed.

Technical Specifications 

• Model: PVD-1B-28P-8G3-5161A / PVD-1B-29BP-11G5-452 (PVD-1B series)
• Maximum displacement: 17 × 2 = 34 cm³/rev
• Rated pressure: 24.5 MPa (245 bar)
• Peak pressure: Series standard 24.5 MPa
• Maximum speed: 2700 rpm
• Rated speed: 2500 rpm
• Minimum speed: 900 rpm
• Control: Constant horsepower (constant torque) control as standard; optional gear-pump feedback
• Mounting flange: SAE B 2-bolt
• Shaft: Z=13, centering diameter approx. 101.6 mm
• Weight: approx. 15 kg
• Design features: Internal drain (no external case drain line required), dual split-flow configuration, optional rear-mounted single or dual gear pumps

Key Technical Advantages

1. Precision-machined swash plate and valve plate keep port-to-port flow variation below 1%, delivering highly synchronized flow to left and right travel motors for superior straight-line stability.
2. Axial-piston architecture maintains high volumetric efficiency even in the high-pressure range, minimizing internal leakage, heat generation, and fuel consumption.
3. Standard constant-horsepower control (with optional gear-pump feedback) keeps pump drive power within the engine power curve, effectively preventing engine stall.
4. Long-life bearings and wear-resistant rotating group combined with internal-drain design reduce external leak points and improve overall machine reliability and serviceability.
5. 100% interchangeability plus full operating-condition testing ensures exact match of mounting dimensions, ports, and control characteristics with original Nachi PVD-1B units, minimizing downtime.

Application Areas

Designed for 3–3.5 tonne class mini crawler excavators including Caterpillar 302.5, Kubota KX61-3, Yanmar Vio30 / Vio35, Hitachi EX35 / ZX30 / ZX30U-2 and equivalent models as the main hydraulic pump for travel, swing, and working equipment (boom, arm, bucket). Also suitable for comparable small excavators and construction machinery hydraulic circuits from other manufacturers.

Expert Maintenance Tips

1. Before installation, verify rotation direction (P = right-hand) and spline match; ensure precise flange centering and avoid radial or axial overloads.
2. Fully bleed the system before first start-up. Use hydraulic oil meeting or exceeding ISO 4406 18/16/13 cleanliness; recommended viscosity 22–68 cSt.
3. Periodically monitor case temperature and any leakage. The internal-drain design eliminates the need for an external case drain line, but free case oil return must be maintained.
4. When changing filters and oil, inspect the valve plate and pistons for wear. Perform preventive maintenance at the end of design life or when flow decreases to maximize hydraulic-system longevity.