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

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 key idea is how many positions the valve has and what the center position does. A 4/2 valve has four ports and two end positions, so it simply connects P to A and T to B to extend or P to B and T to A to retract. There’s no neutral or middle position, so the cylinder tends to move to an end and there isn’t a built-in way to hold it in a mid-stroke without extra components. A 4/3 valve adds a center (neutral) position, giving three positions total. In the center position, the flow to the actuator is typically blocked, which holds the cylinder in place and prevents movement until the valve is actuated again. This is the extra capability that lets you stop the cylinder midway. So, the difference is that the 4/3 valve provides a center/neutral position to hold the cylinder at a chosen position, whereas the 4/2 valve does not. The other statements are inconsistent with how these valves actually operate.

The key idea is how many positions the valve has and what the center position does. A 4/2 valve has four ports and two end positions, so it simply connects P to A and T to B to extend or P to B and T to A to retract. There’s no neutral or middle position, so the cylinder tends to move to an end and there isn’t a built-in way to hold it in a mid-stroke without extra components.

A 4/3 valve adds a center (neutral) position, giving three positions total. In the center position, the flow to the actuator is typically blocked, which holds the cylinder in place and prevents movement until the valve is actuated again. This is the extra capability that lets you stop the cylinder midway.

So, the difference is that the 4/3 valve provides a center/neutral position to hold the cylinder at a chosen position, whereas the 4/2 valve does not. The other statements are inconsistent with how these valves actually operate.