A7V250HD5.1RZF00 Rexroth Bent Axis Hydraulic Pump 350Bar

Product Overview

The A7V250HD5.1RZF00 is a Bosch Rexroth A7V series bent-axis axial piston variable displacement pump, series 5.1, nominal size 250 cm³/rev. Designed for hydrostatic transmissions in open circuits, the flow is proportional to drive speed and displacement, with stepless variation at constant drive speed. The A7V series spans 13 sizes from 20 to 500 cm³/rev, with a high-pressure range up to 400 bar.

The full order code A7V250HD5.1RZF00 decodes as follows: A7V indicates the bent-axis variable pump series; 250 is the nominal displacement of 250 cm³/rev; HD denotes hydraulic control, pressure related — a pilot-pressure-dependent control that drives the control piston to vary the swash angle for stepless displacement adjustment; 5.1 is the series designation; R indicates right-hand rotation (clockwise, viewed from shaft end); Z specifies splined shaft; F specifies SAE flange port connections; and 00 indicates no auxiliary equipment. This HD control configuration is particularly suited to mobile machinery main hydraulic circuits that require remote hydraulic pilot operation.

Manufactured to exact Rexroth A7V platform specifications, this pump delivers true drop-in interchangeability — identical mounting flange, shaft spline, port positions, and displacement rating. Every unit undergoes 100% simulated operating condition testing before shipment.

Technical Specifications 

• Model: A7V250HD5.1RZF00

• Series: A7V series 5.1

• Design: Bent-axis axial piston variable displacement pump

• Displacement: 250 cm³/rev (variable, stepless from Vgmin to Vgmax)

• Rated Working Pressure: 350 bar (35 MPa)

• Peak Pressure: 400 bar (40 MPa)

• Maximum Speed: 1800 rpm (continuous duty)

• Rotation Direction: Right hand (clockwise, viewed from shaft end)

• Control Type: HD hydraulic pilot pressure control

• Shaft Specification: Splined shaft (Z)

• Port Connection: SAE flange (F)

• Auxiliary Equipment: None (00)

• Weight: 135–145 kg (depending on configuration)

• Theoretical Flow at 1800 rpm (Vgmax): 450 L/min

• System Type: Open-circuit hydraulic system

• Operating Fluid: Mineral hydraulic oil and fire-resistant fluids

Key Technical Advantages

1. High Power Density and Volumetric Efficiency from Bent-Axis Design

The A7V series employs a bent-axis configuration in which pistons act directly on the drive plate through connecting rods, shortening the torque transmission path for higher mechanical efficiency than swashplate designs. The rotary group features a spherical control area that enables automatic self-centering of the cylinder barrel and valve plate during rotation, with reduced circumferential velocity and excellent volumetric efficiency. The improved port plate design reduces noise levels by approximately 5 dBA.

2. Flexible Variable Control via HD Hydraulic Pilot Operation

The HD control is a hydraulic pilot-pressure-dependent control that drives the control piston via an external pilot pressure signal to continuously vary the bent-axis angle. Compared with LV constant horsepower control and DR constant pressure control, HD control offers more direct response, making it ideal for mobile machinery main hydraulic circuits that require real-time displacement adjustment based on operating conditions. An optional pressure cut-off function (D built-on) automatically returns displacement to zero when system pressure reaches the set value.

3. Heavy-Duty Bearing System and Long Service Life

The pump incorporates robust roller bearings that handle high axial and radial loads under demanding conditions. The bearings support hydrostatic unloading, enabling continuous operation at pressures up to 400 bar. According to manufacturer data, average bearing service life is approximately 10,000 hours, beyond which replacement is recommended. Bearing clearance directly affects the internal clearances of the three friction pairs and the hydrostatic bearing film thickness — periodic bearing inspection is therefore critical to pump longevity.

4. Broad Size Coverage with Standardized Interfaces

The A7V series covers 13 sizes from 20 to 500 cm³/rev. Mounting flanges, shafts, and ports use standardized designs (SAE flanges, DIN/ISO splines) for interface compatibility across displacement sizes. The A7V250 directly replaces the main hydraulic pumps in Liebherr R944/R954/R964 excavators, Komatsu PC600/PC650 excavators, Atlas AR160/AR180 loaders, Fuchs MHL380/MHL390 material handlers, Sennebogen 340/350 material handlers, and Demag AC120 / Faun ATF110 cranes.

5. 100% Simulated Operating Condition Testing

Every pump undergoes a comprehensive factory test protocol: continuous operation at 350 bar rated pressure to verify volumetric and total efficiency, 400 bar peak pressure cycling to validate housing and seal integrity, and full-speed-range verification of displacement control linearity and HD control response characteristics. Test documentation is supplied with each unit.

Application Areas

• Large Excavators: Liebherr R944/R954/R964, Komatsu PC600/PC650 main hydraulic pumps

• Material Handlers: Fuchs MHL380/MHL390, Sennebogen 340/350 hydraulic systems

• Wheel Loaders: Atlas AR160/AR180, O&K L150/L180 implement drives

• Large Cranes: Demag AC120, Faun ATF110 main hydraulic drive systems

• Industrial Power Units: Die-casting machines, forging presses, large machine tool hydraulic systems

• Mining & Metallurgical Equipment: Mine transport vehicles, continuous casting machine hydraulic drives

Expert Maintenance Tips

1. HD Control Pilot Pressure Calibration and Verification

HD control depends on an external pilot pressure signal for displacement regulation. After pump or control valve replacement, verify the pilot pressure-to-displacement relationship at rated speed and 50% displacement to confirm it falls within the factory calibration curve. Pilot signal line cleanliness should be maintained at NAS 8 or better — particulate contamination can cause control piston sticking or sluggish response.

2. Proper Use of Case Bearing Flushing Circuit (U-Port)

Pumps of A7V250 size and above are equipped with a dedicated U-port for bearing flushing. Use a hydraulic filter unit to flush oil in through the K1 port and out through the K2 port. Bearing flushing helps control bearing operating temperature and extend bearing life. Recommended flushing flow is 3–5 L/min, with flushing fluid cleanliness at ISO 18/16/13 or better.

3. Periodic Bearing Clearance Assessment

The bearing is the most critical component in a piston pump. Once bearing clearance increases, it becomes impossible to maintain the correct clearances of the three internal friction pairs, and the hydrostatic bearing film thickness is compromised, sharply reducing pump service life. Average bearing life is approximately 10,000 hours; replacement is recommended beyond this interval. Removed bearings require professional instruments for clearance measurement — visual inspection should check for scoring or discoloration on roller surfaces.

4. Mandatory Case Pre-Fill and Air Purging at First Installation

Starting a bent-axis piston pump dry will cause catastrophic wear to the valve plate and piston/cylinder interface within seconds. After installation, fill through the highest case port with clean hydraulic fluid filtered to ≤10 μm until oil overflows. Open the highest case bleed plug and run the pump at idle until bubble-free oil flows continuously. Do not apply load until the system is confirmed air-free.

5. Fluid Cleanliness and Oil Change Intervals

Hydraulic fluid cleanliness must be maintained at all times — the higher the cleanliness, the longer the pump service life. Maintain system cleanliness at NAS 9 or ISO 18/16/13 or better. Replace hydraulic fluid every 1000–3000 operating hours or every six months. Replace the system return filter at 200 hours for the first interval, then inspect or replace every 500 hours.