Bosch Rexroth A4VSO Axial Piston Variable Pump
Overview
The Bosch Rexroth A4VSO is a robust axial piston variable pump of swashplate design, built for high-pressure hydrostatic drives in an open circuit. Rexroth describes it in data sheet RE 92050 as a pump for industrial applications, covering sizes 40 to 1000 cm³ per revolution with a nominal pressure of 350 bar and a maximum pressure of 400 bar, rising to 380 bar nominal and 420 bar maximum for selected controls with port plate 36. Flow is proportional to drive speed and displacement, and the displacement can be changed continuously by adjusting the swashplate, which makes the pump the heart of many large presses, test rigs and heavy industrial power units.
Seven Star LLC supplies the Bosch Rexroth A4VSO and its control devices to industrial plants, OEM packagers and maintenance contractors in the Sultanate of Oman and across the GCC. Requests usually come from metal forming and extrusion lines, steel and aluminium plants in Sohar, marine and offshore power units, and hydraulic test benches used by service companies in Muscat. With engineering support in Muscat, our team helps read the existing type code, identify the size, controller, shaft, port plate and through drive, and source a like-for-like replacement or a correctly configured new pump.
Operating Principle
In the Bosch Rexroth A4VSO a cylinder block with axial pistons rotates with the drive shaft. The pistons are supported on a swashplate through slippers, so as the block turns each piston reciprocates, drawing fluid from the suction port S and delivering it to the pressure port B. The stroke of the pistons, and therefore the displacement, depends on the swashplate angle. A control device sets that angle: when the swivel angle is increased the pump delivers more flow at a given speed, and when it is reduced toward zero the flow falls while the drive keeps running. Rexroth lists a minimum high-pressure-side pressure of 15 bar and a maximum rate of pressure change of 16000 bar/s for the unit.
The result is that the Bosch Rexroth A4VSO supplies only the flow and pressure the consumers need. With the pressure controller DR, for example, the pump holds the set pressure and swivels back to a smaller displacement once the system pressure reaches the command value, with a setting range of 50 to 350 bar. For the Bosch Rexroth A4VSO this reduces wasted energy and heat compared with a fixed pump and relief valve, and it allows one pump to handle rapid traverse, pressing and holding phases in a machine cycle. The data sheet also highlights excellent suction characteristics, a low noise level and a pre-compression volume that reduces pressure pulsation.
Engineering Design of the Bosch Rexroth A4VSO
The Bosch Rexroth A4VSO is a modular design. The same rotary group can be combined with a long list of control devices, including pressure controllers DR and DP for parallel operation, hyperbolic power controllers LR2 and LR3, pilot-pressure related hydraulic controls HD, volume-dependent hydraulic controls HM, manual control MA, electric motor control EM, the digital and analog electro-hydraulic control systems HS5 and EO, the secondary speed controls DS and the electro-hydraulic control system DFE1. A through drive allows further pumps to be mounted on the same shaft, and combination pumps A4VSO plus A4VSO are documented in the data sheet.
Rexroth notes that the Bosch Rexroth A4VSO can be installed in any position and is suitable for variable-speed drives. An optical swivel angle indicator is fitted, and a special version allows HFC operation with reduced data. A drain line from the case to the reservoir is required, with a maximum static case pressure of 4 bar absolute, and suction pressure must be at least 0.8 bar absolute for the version without charge pump. The pump is designed for HLP mineral oil according to DIN 51524, with the optimum operating viscosity between 16 and 36 mm²/s and FKM shaft seals for continuous operation up to +110 °C measured at port T.
Key Features
The key features of the Bosch Rexroth A4VSO, as listed by the manufacturer, are summarised below.
- The Bosch Rexroth A4VSO uses an axial piston rotary group of swashplate design for hydrostatic drives in an open circuit.
- Ten sizes from 40 to 1000 cm³ per revolution cover small power units up to very large press drives.
- Nominal pressure is 350 bar, or 380 bar for selected controls with port plate 36, with maximum pressure of 400 or 420 bar.
- Flow can be changed continuously by adjusting the swashplate, and it is proportional to drive speed and displacement.
- A broad range of hydraulic, mechanical and electro-hydraulic control devices adapts the pump to almost any machine function.
- A pre-compression volume reduces pressure pulsation, which supports a low noise level.
- Through-drive options allow additional pumps to be mounted, and any installation position is possible.
- Long service life and suitability for variable-speed drives make the unit a good fit for energy-saving pump drives.
Industrial Applications
Typical applications of the Bosch Rexroth A4VSO in the region include forging and extrusion presses, steel mill and rolling equipment, aluminium casthouse machinery in Sohar, large hydraulic power units on offshore and onshore oil and gas facilities, pipe-handling and test equipment, and marine systems such as steering gear and deck machinery. Because the same Bosch Rexroth A4VSO frame size can be ordered with pressure, flow, power or electronic control, engineers often standardise on this pump family across several machines to simplify spares in remote locations such as Duqm, Salalah or interior oil fields.
Seven Star LLC supplies the Bosch Rexroth A4VSO alongside the smaller Bosch Rexroth A10VSO axial piston variable pump for medium-pressure duties, pressure valves such as the Rexroth DB10G2-5X/50 pressure relief valve, and filtration such as the Bosch Rexroth R928006678 hydraulic filter element. Customers in Muscat, Sohar and across the GCC use us to coordinate pump, valve and filter supply for the same power unit, with engineering support from our Muscat office.
Technical Specifications
The table summarises Bosch Rexroth A4VSO data from RE 92050 (2023-06-15) for the standard rotary group; values per size are taken from the manufacturer table and apply at the stated conditions.
| Parameter | Specification |
|---|---|
| Model | Bosch Rexroth A4VSO series 1x and 30 |
| Type | Axial piston variable pump, swashplate design, open circuit |
| Sizes (displacement) | 40, 71, 125, 180, 250, 355, 370, 500, 750, 1000 cm³/rev |
| Nominal pressure | 350 bar (port plates 13 and 25); 380 bar (port plate 36) |
| Maximum pressure | 400 bar (port plates 13 and 25); 420 bar (port plate 36) |
| Nominal speed at Vg max | 2600 rpm (size 40) down to 1000 rpm (size 1000) |
| Flow at nominal speed | 104 l/min (size 40) up to 1000 l/min (size 1000); 1125 l/min for size 750 at 1500 rpm |
| Power at nominal speed, 350 bar | 61 kW (size 40) up to 656 kW (size 750 at 1500 rpm) |
| Torque at Vg max, 350 bar | 223 Nm (size 40) up to 5565 Nm (size 1000) |
| Weight without through drive | approx. 39 kg (size 40) up to 605 kg (size 1000) |
| Suction pressure | minimum 0.8 bar absolute, maximum 30 bar (without charge pump) |
| Case pressure | maximum 4 bar absolute static, 6 bar absolute peaks |
| Viscosity | optimum 16 to 36 mm²/s; continuous 10 to 400 mm²/s |
| Hydraulic fluid | HLP mineral oil to DIN 51524; HFC with special version |
| Controls | DR, DP, LR2, LR3, HD, HM, MA, EM, HS5, EO, DS, DFE1 and options |
How to Order
For a quotation on the Bosch Rexroth A4VSO, send Seven Star LLC the complete type code or material number from the pump nameplate, or the required size, control, shaft and port plate. Our engineering team in Muscat will check the configuration against the manufacturer data, share the technical datasheet for download and prepare a formal RFQ response. Seven Star LLC supplies Rexroth pumps and hydraulic components to customers in Oman and the GCC with engineering support.
- Datasheet Bosch Rexroth RE 92050 Axial Piston Variable Pump A4VSO Series 1x and 30 Data Sheet (2023-06-15) Download
Bosch Rexroth hydraulic components listed here
Four items are listed. The A10VSO is an axial piston variable displacement pump of swashplate design for open circuits. The DB10G2-5X/50 is a pilot-operated pressure relief valve, and the MHDBD10K2-1X/315V is a direct-operated relief valve in cartridge form. R928006678 is a hydraulic filter element. Older parts may be marked Mannesmann Rexroth; the type codes are read the same way.Ordering Rexroth parts: what we need
The safest reference is the ten-digit material number beginning with R9, printed on the nameplate beside the type code. Send both, with a nameplate photo. For an A10VSO pump, the full code matters: size, controller type, series, direction of rotation, seals, shaft and port plate. For relief valves, give size, pressure stage and seal material. For filter elements, the material number or the complete element code is enough. We supply to buyers across the GCC.Browse Bosch Rexroth products by category: Safety Relief Valves, Filtration Elements, Pumps.
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