If you have reviewed all these pages and understand how to draw all the valves up to a 4/2 or a 5/2, then drawing the 5/3 or the 4/3 should not present too many difficulties for you.
The purpose of a valve schematic is to show all of the possible positions for that one air valve. This allows the system designer to insert a particular valve into an air circuit diagram, to show system builders what valves to acquire, and the condition of that valve so it can be installed in the circuit in the position necessary when the circuit is shut down.
The completed circuit schematic will also show all the valve actuators necessary for each air valve in that circuit, for the circuit to operate as designed.
On the page "drawing the 5/2 air valve", the final schematic for the 5/2 was as shown in Fig. 53.
Fig. 53 shows both positions of this 5/2 valve and the corresponding flow paths, depending on that valve position. You can see how the flow paths change whether it is the right side or the left side of the valve that is currently in control.
The first number in a valve designation, in this case a five, indicates that this valve will have five ports. The second number indicates the number of positions for that valve, so a 5/3 valve will have three positions, not two as shown in Fig. 53. Where and how does that third position get drawn? Please see Fig. 55, below.
In drawing the three position valve schematic, we essentially split the 5/2 valve schematic in half. We add a space in the center. This is where we will show the flow paths available for the third position possible with the 5-3 (also known as 5/3) valve.
This page discusses 5/3 and 4/3 valves in detail. In it we learn that the third position in a 5/3 valve is a center position. The air control mechanism inside 5/3 valve (usually a spool of some sort) is shifted into the center position inside the valve by one of the two internal spring actuators normally located inside the valve at each end of the internal spool. These springs center the spool into the valves third position.
The internal valve spool might have - O - rings installed on it. It might have a bonded Buna-rubber surface, it might be all aluminum or plastic and slide back and forth inside a tube packed with "O" ring type seals, or it might be a high tolerance, machined metal-to-metal spool. All of these varieties are available from the major valve manufacturers around the world.
Each spool style have their benefits and their negatives and knowing them will help you choose the valve technology that best suits the application. Much information about each valve type will be available from that manufacturer's website, and a prudent valve buyer will take the time to research on those sites.
These three possible central-position flow configuration are note available from all valve manufacturers. If you are looking for a specific 5/3 valve function, you may have to shop around to find the source that makes that version.
In order to complete the schematic for our 5/3 compressed air valve, we have to determine which of these three configurations we need for our valve, and insert the schematic for that flow path between the other two positions.
Here are the schematics for the three positions: