🔍 Key Concepts

• Positive displacement pumps vs. variable displacement pumps • Construction and operation of gear pumps, radial piston pumps, and axial piston pumps • How displacement per revolution changes (or does not change) with speed and geometry

💭 Think About

• For choice A, think about whether changing pump drive speed changes the pump’s displacement per revolution, or only its flow per unit time. • For choice B, visualize a radial piston pump: where are the pistons, and which component rotates – the cylinder block or the shaft in typical designs? • For choice C, recall what the swash plate or tilting box does in an axial piston pump: at what tilt angle is the displacement per revolution zero, and at what angle is it maximum?

✅ Before You Answer

• Check whether gear pumps are normally fixed displacement or variable displacement designs. • Confirm the typical configuration of a radial piston pump: Are the pistons radial in a rotating block or sliding in a stationary block with a rotating pintle? • For an axial piston pump, verify the relationship between tilting box (swash plate) angle and pump displacement per revolution (zero vs. intermediate vs. maximum angle).