Variable Axial Piston Pump Bosch Rexroth A6VM, Components Control Function and How it works? The A6VM series by Bosch Rexroth is a variable displacement axial piston pump with a bent-axis design, suitable for hydrostatic drives in both open and closed circuits. It features high efficiency and robust performance under demanding conditions. A minimum pressure of 25 bar absolute on the high-pressure side (A or B) is required to prevent damage. Proper hydraulic fluid selection, as per the Bosch Rexr