🔍 Key Concepts

• fixed-displacement vs. variable-displacement hydraulic machines • how speed of a hydraulic motor is related to flow rate and displacement • difference between controlling speed and controlling torque/pressure in hydraulics

💭 Think About

• Ask yourself: with a fixed-displacement motor, can the amount each revolution uses change, or is something else changed to alter speed? • Which option describes something that is actually adjustable in a radial piston motor design, and which options sound more like variable-displacement pump features? • Think about the basic formula: motor speed depends on how much fluid per minute goes into the motor and how much volume it uses per revolution.

✅ Before You Answer

• Identify which choices talk about displacement (volume per revolution) and which talk about flow rate (volume per minute). • Confirm that in a fixed-displacement device, the displacement does not change during operation. • Make sure the choice you pick directly affects rpm (revolutions per minute), not internal recirculation or geometry that would be fixed in a "fixed-displacement" motor.