The pistons suck in fluid during half a revolution and push fluid out during the other half.

Shown on edge on the far right in the animation is a dark stationary disk. It contains two semi-circular ports. It is shown again in a head-on view below, right.

These ports allow the pistons to draw in fluid as they move toward the swash plate (on the backside and not shown here) and discharge it as they move away.

For a given speed swash plate pumps can be of fixed displacement like this one, or variable by having a variable swash plate angle. The greater the slant the further the pistons move and the more fluid they transfer.

Note similarities to, and differences from, the wobble pump, radial piston pump, and bent axis pump.

(This is a 12-frame animation, converted to animated GIF format for Internet use and transmission. (Note: On some Internet browsers it may be displayed much less smoothly than the CD-ROM version, where the frames are timed to a thousandth of a second.))

This shows the port arrangement for this pump.