Its angle sets how far each piston strokes per revolution, which sets displacement and therefore flow at a given shaft speed. Tilting it while the pump runs varies flow continuously, and that single control point is what makes pressure compensation and load sensing straightforward to implement.

The ability to drive a second pump from the rear of the first, so one prime mover feeds several independent circuits without a gearbox or split coupling. On power packs and mobile plant it saves significant space, cost and complexity, and it is worth checking for when specifying the first pump.

Very. The slipper-on-swashplate interface and the valve plate both run on extremely thin fluid films that particles disrupt, so meeting the specified cleanliness target is a requirement rather than good practice. Most premature failures trace to filtration or fluid condition rather than to the pump itself.

More so than screw or vane pumps, because the piston stroking generates pressure ripple and the valve plate transition contributes structure-borne noise. On mobile equipment that is generally acceptable; in an indoor installation or a noise-sensitive environment it can be the reason a different pump type is chosen.

It is internal leakage returned to tank, and it rises measurably as internal clearances wear. Measuring it gives a direct indication of pump condition without dismantling anything, and a rising trend flags wear long before the operator notices lost performance at the actuators.

Fixed where the circuit needs one flow and simplicity matters; variable where flow demand changes, because a variable pump delivers only what is needed instead of producing full flow and dumping the excess over a relief valve. In any duty cycle with idle periods the energy saving is substantial.

Good ones. Axial piston pumps are sensitive to inlet restriction and will cavitate if starved, which damages the valve plate and slippers quickly. Adequate suction line size, a clean suction strainer and correct reservoir arrangement matter more than they do on a gear pump.