The A4VSO is a swashplate-type axial piston variable pump designed for efficient hydrostatic drives in open circuits. Its notable features include excellent suction characteristics, low noise levels, long service life, high power-to-weight ratio, and a modular design. It offers a wide range of displacement sizes, from 40 to 1000 ml/rev, and can handle nominal pressures up to 350 bar with peak pressures reaching 400-420 bar.

These pumps are widely used in heavy-duty industrial applications such as ceramic presses, refractory material presses, steel and forging equipment, metallurgical machinery, mining machinery, marine machinery, petroleum equipment, engineering machinery, and machine tool control systems.

The series offers a comprehensive range of control types. The most common include DR/DRG for constant pressure control, LR for hyperbolic (constant) power control, and EO2 for electro-proportional control. Other options include manual (MA), hydraulic (HW, HM, HS, HD), and electronic (EM, EO).