Bosch Rexroth axial piston units come in two basic forms — fixed displacement and variable displacement — and as both pumps and motors. Choosing the right combination has a big impact on efficiency, control and cost. This guide explains the differences and points you to the right range.
Fixed vs variable displacement
A fixed displacement unit moves the same volume of oil per revolution. It is simpler, robust and cost-effective, and ideal when the flow (for a pump) or speed/torque (for a motor) does not need to vary during operation. A variable displacement unit can change its swivel angle to deliver exactly the flow or speed the machine needs at any moment, saving energy and giving fine control — the preferred choice for demanding mobile and industrial hydrostatic drives.
Pump or motor?
A pump converts mechanical power from the prime mover into hydraulic flow. A motor does the reverse, converting hydraulic flow back into rotation to drive a wheel, drum, fan or gearbox. Bosch Rexroth offers axial piston versions of both, in fixed and variable forms.
Choosing your Bosch Rexroth range
- Axial Piston Variable Pump — the workhorses for open and closed circuits (A10VSO, A10VO, A4VG, A4VSO, A11V(L)O, A7VO and more). Steplessly adjustable flow for energy-efficient systems.
- Axial Piston Fixed Pump — robust, cost-effective constant-flow pumps (A2FO, A4FO, A17FO, A10FZO) for simpler circuits.
- Axial Piston Variable Motor — variable-speed drive motors (A6VM, A6VE, A10VM, A36VM) for travel drives, fan drives and gearboxes.
- Axial Piston Fixed Motor — compact constant-displacement motors (A2FM, A2FE, A4FM, A10FM) for a fixed drive ratio.
Open vs closed circuit
In an open circuit the pump draws oil from a reservoir and returns it there — common for industrial machinery. In a closed circuit the oil circulates directly between pump and motor, ideal for hydrostatic travel drives. Rexroth axial piston units are available for both; the datasheet on each series page states the circuit type.
Need help choosing? Twin Hydraulics Engineering is a Bosch Rexroth Certified Excellence Partner covering the whole of Malaysia. Send us your application or type code and we’ll recommend the right unit. Request a quote.
The full Bosch Rexroth pump range
Beyond axial piston units, Twin Hydraulics Engineering supplies the complete Bosch Rexroth pump programme. Choose by principle:
- Internal Gear Pumps (PGH, PGF, PGP, PGM) — quiet, efficient pumps ideal for low-noise and variable-speed drives.
- External Gear Pumps (the AZP program — AZPB, AZPF, AZPN, AZPG, AZPJ and multiple pumps) — compact, robust and cost-effective for mobile and industrial hydraulics.
- Vane Pumps (PVV, PVQ, PVH fixed and PV7 / BPV variable) — smooth, quiet medium-pressure pumps for power units.
- Radial Piston Pumps (PR4) — fixed-displacement pumps for very high pressures up to 700 bar.
Not sure which principle suits your application? Contact our engineering team and we’ll recommend the right pump.
