Draw a 5/3 or a 4/3 air valve

Drawing a 5/3 air valve; Please, if you haven’t already done so, take a few minutes to look at the other pages on this site about drawing air valves. They are:

If you have reviewed 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 will not be complex.

A valve schematic’s purpose is to show all of the possible positions for that one air valve, to allow the system designer to insert a particular valve in an air circuit, and to show system builders the condition of that valve when it is at rest in the circuit, and the valve actuators necessary to ensure that the valve will work as desired.

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 the valve position. You can see how the flow paths change whether it’s the right side or the left side of the valve that is currently in “control”.

We know that the first number in a valve designation, in this case a five, shows 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 does that third position get drawn? Please see Fig. 55, below.

We split the 5/2 valve schematic, and added a space in the center, where we will add the flow paths determined by the type of 5/3 valve this is.

I do note that “splitting the schematic” is a whole lot easier done electronically. This is why, when drawing valves with pencil and graph paper, a good eraser is essential. Be optimistic! As you get comfortable with drawing different styles of valves, fewer errors will occur and you’ll have to correct fewer mistakes.







On the page that discusses 5/3 and 4/3 valves it is noted 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 two internal spring valve actuators. There is a spring located inside the valve at each end of the internal spool. When no external valve actuator is being exerted on the valve these springs center the spool into the valve’s third position.

The spool is the air-path-control device found inside most 4 or 5 ported valves, and some 3 ported valves. Normally spools are not found in 2 position valves.

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. Each have their benefits and their negatives. Each type might be made by a different manufacturer, and they will attest to the superiority of their design over every other valve manufacturer’s, of course.

The third position in a three position valve can be one of the following: