LESSON 07 · INTERMEDIATE · SHORT LESSON
Directional Control Valves
A directional valve selects which lines receive oil. The number of positions and centre connections change circuit behaviour.
What is happening technically?
A 4/3 valve has four ports and three positions. P is supply, T is return, and A and B are work ports. The centre symbol determines unloading and load-holding behaviour.
In practice
A replacement valve with a different centre configuration can change the machine's standby behaviour.
Educational diagram only; not a manufacturing or safety circuit. The pilot line illustrates the line style only.
Symptom → check → solution
If movement, pressure or temperature changes, first identify the conditions in which the symptom occurs. Record existing gauge readings. Base maintenance or circuit examination on causes confirmed by measurements.
Select your symptom in Fault Hunter →Quick check
Which is the correct approach before replacing a component?