What is the difference between a 4/2 way valve and a 4/3 way valve in terms of control of a hydraulic cylinder?

• A. A 4/2 can only fully extend/retract; a 4/3 has an additional function to stop the cylinder midway.
• B. A 4/3 can only extend; a 4/2 can stop midway.
• C. They function identically in controlling cylinder movement.
• D. A 4/2 cannot be used for extension.

Answer: (A)

The main idea here is that the number of positions in a directional control valve controls whether you have a neutral or hold capability for the cylinder. A valve with four ports and two positions can switch the hydraulic flow to drive the cylinder in one direction or the other, but it has no built‑in center or neutral position. That means the cylinder tends to move until it reaches a mechanical limit or until something else stops it; there isn’t a built‑in way to hold the piston at a mid‑stroke just by the valve.

A valve with four ports and three positions adds a center, or neutral, position. In that center position, flow to the cylinder ports is isolated (or balanced in a way dictated by the center design), so the cylinder can be held at whatever position it’s in, including a mid‑stroke, without continuous pressure pushing it one way or the other. This center-off capability is the extra function that lets you pause or stop the cylinder in mid‑travel, assuming the load remains in place.

So, the difference is the added center/off position in the 4/3 valve that allows holding the cylinder in a chosen position, whereas the 4/2 valve lacks that neutral position and cannot deliberately hold mid‑stroke. Extensions and retractions are possible with both, but mid‑stroke stopping is the distinguishing feature of the 4/3 valve.