AA2FM250/60W-VSD527

The AA2FM250/60W-VSD527 axial piston unit is produced by Bosch Rexroth as part of the A2FM Fixed Motors series. It serves as a constant-displacement hydraulic motor for closed or open-circuit drives where stable, high power density is required. The displacement is 250 cm³ per revolution, so each shaft rotation moves a fixed fluid volume that simplifies flow calculations in machine cycles. At its nominal speed of 2700 rpm the motor accepts an inlet flow of 675 L/min, enabling compact high-speed drives in mobile or industrial equipment. Continuous operation is supported at a nominal pressure of 350 bar, and the motor can develop 1393 Nm of torque at that pressure to turn heavy loads without an external gearbox. The housing and rotating group tolerate a maximum pressure of 400 bar for temporary overload conditions, while the circuit must maintain at least 25 bar of high pressure to keep internal components firmly seated and lubricated.

The design allows a total pressure differential of 700 bar between high and low ports during dynamic events, yet internal leakage is limited by a peak case pressure of 10 bar and a continuous differential case pressure of 2 bar to protect seals. A case volume of 2.5 L provides sufficient space to absorb thermal expansion of the hydraulic oil and to smooth pulsations. The rotating assembly has a moment of inertia of 0.061 kg·m², reducing drive-train acceleration demands, and a rotary stiffness of 73.1 kNm/rad to maintain shaft alignment under load. Rapid load changes are handled by a rate of pressure rise of 9000 bar/s when a pressure relief valve is installed and 16000 bar/s when it is omitted, giving the motor flexibility in circuits with different damping strategies. Together these characteristics define predictable performance in equipment requiring robust, fixed-displacement hydraulic actuation.