Five-Port / Four-Way Directional Valve

Five-Port / Four-Way Directional Valve

Four-way valves are also available with five external ports, one pressure port, two
actuator ports, and two exhaust ports. Such valves provide the same basic control of
flow paths as the four-ported version, but have individual exhaust ports. In the fluid
power field this is referred to as a "five-ported, four-way valve." This type of valve
brings all flow paths to individual external ports. The pressure port is connected to
system pressure after a regulator. Actuator ports are connected to inlet and outlet
ports of a cylinder or motor. Each exhaust port serves an actuator port.

Four-Way Directional Valve

Four-Way Directional Valve

Perhaps the most common directional valve in simple pneumatic systems consists of
pressure port, two actuator ports and one or more exhaust ports. These valves are
known as four-way valves since they have four distinct flow paths or "ways" within
the valve body.
A common application of four-ported four-way directional valve is to cause
reversible motion of a cylinder or motor. To perform this function, spool connects
the pressure port with one actuator port.
At the same time, the spool connects theother actuator port with the exhaust port. This is a four-ported four-way valve.

Three-Way Directional Valve

Three-Way Directional Valve


A three-way directional valve consists of three ports connected through passages
within a valve body that are shown here as port A, port P and port Ex. If port A is
connected to an actuator, port P to a source of pressure and port Ex is open to
exhaust, the valve will control the flow of air to (and exhaust from) Port A.
The function of this valve is to pressurize and exhaust one actuator port. When the
spool of a three-way valve is in one extreme position, the pressure passage is
connected with the actuator passage. When in the other extreme position, the spool
connects the actuator passage with the exhaust passage.

Two-Way Directional Valve

Two-Way Directional Valve

A two-way directional valve consists of two ports connected to each other with
passages, which are connected and disconnected. In one extreme spool position, port
A is open to port B; the flow path through the valve is open. In the other extreme,
the large diameter of the spool closes the path between A and B; the flow path is
blocked. A two-way directional valve gives an on-off function.

Functional Types of Directional Control Valves

Functional Types of Directional Control Valves

One method of classifying a directional control valve is by the flow paths that are
set up in its various operating conditions. Important factors to be considered are the
number of individual ports, the number of flow paths the valve is designed for andinternal connection of ports with the movable part.
There is function type of directional control valve :
1. Two-Way Directional Valve
2. Three-Way Directional Valve
3. Four-Way Directional Valve
4. Five-Port / Four-Way Directional Valve

Directional Control Valves

Directional Control Valves

To change the direction of airflow to and from the cylinder, we use a directional
control valve. The moving part in a directional control valve will connect and
disconnect internal flow passages within the valve body. This action results in a
control of airflow direction.
The typical directional control valve consists of a valve body with
four internal flow passages within the valve body and a sliding spool.

Shifting the spool alternately connects a cylinder port to supply pressure or the
exhaust port. With the spool in the position where the supply pressure is connected
to port A and port B is connected to the exhaust port, the cylinder will extend. Then,
with the spool in the other extreme position, supply pressure is connected to port B
and port A is connected to the exhaust port, now the cylinder retracts. With a
directional control valve in a circuit, the cylinder's piston rod can be extended or
retracted and work performed.

Sizing a Cylinder

Sizing a Cylinder

These pressure, force and area relationships are sometimes illustrated as shown
below to aid in remembering the equations.

To determine the size cylinder that is needed for a particular system, certain
parameters must be known. First of all, a total evaluation of the load must be made.
This total load is not only the basic load that must be moved, but also includes any
friction and the force needed to accelerate the load. Also included must be the force
needed to exhaust the air from the other end of the cylinder through the attached
lines, control valves, etc. Any other force that must be overcome must also be
considered as part of the total load. Once the load and required force characteristics
are determined, a working pressure should be assumed. This working pressure that
is selected MUST be the pressure seen at the cylinder's piston when motion is taking
place. It is obvious that cylinder's working pressure is less than the actual system
pressure due to the flow losses in lines and valves.
With the total load (including friction) and working pressure determined, the
cylinder size may be calculated using Pascal's Law. Force is equal to pressure being
applied to a particular area. The formula describing this action is:
Force = Pressure * Area
Force is proportional to pressure and area. When a cylinder is used to clamp or
press, its output force can be computed as follows: F = P*A
P = pressure (PSI (Bar) (Pascal's))
F = force (pounds (Newtons))
A = area (square inches (square meters))

Reading Pneumatic Schematic Symbol

Technical Drawing Sheet ( JIS B 0001 )

This is simple guide for about size of technical drawing paper.