🔍 Key Concepts

• Hydraulic follow-up (servo) control for an axial piston pump swashplate • How shifting the spool valve changes which side of the servo piston gets pressure (P) and which gets return (T) • The mechanical feedback link that recenters the valve after the swashplate moves

💭 Think About

• When part "3" is moved to the left, which passages are now connected to P and which to T on each side of the servo piston? Use the blue/red flow paths in the illustration. • Given that pressure is applied to one side of the servo piston and vented on the other, in which direction must part "2" (the piston) move, and how does that motion act on the tilting box control arm? • As the control arm moves, how does the feedback linkage affect the position of part "1" relative to part "3" — does it move together instantly, or does it move after the piston and arm have started to travel?

✅ Before You Answer

• Identify clearly which component is 1, which is 2, and which is 3 on the illustration before choosing. • Trace the hydraulic path from P to the piston chambers and from those chambers to T for the new position of "3". • Verify whether the feedback mechanism is designed to cause immediate, equal movement of parts "1" and "3", or a delayed (lagging) follow-up movement that recenters the valve when the desired swashplate angle is reached.