A device for adjusting the displacement of a fluid pump includes a swashplate supported for pivotal movement about a first axis, and an engine having first and second cylinders. A first piston is located in the first cylinder and secured to the swashplate at a first side of the first axis. A second piston is located in the second cylinder and secured to the swashplate at a second side of the first axis opposite the first side. A plate is secured to the swashplate for pivotal movement about the first axis and is supported for rotary oscillation relative to the swashplate about a second axis. A pump includes a third cylinder and a first plunger located in the third cylinder, secured to the plate for pivotal movement about the first axis and rotary oscillation about the second axis. The plunger displaces fluid from the third cylinder as the plunger reciprocates.