Need explanation with spool valve symbol

Dear atomation experts,

Can you please help me by explaining how spool valve with the attached symbol works?

I know that spring (b) returns the spool valve into initial position (P->A, T->B).
When the el.magnetic coil is energizedm, then the connections are: P->B, T->A).
When voltage is not present, the spring returns the spool in initial position. This Q is probably a symbol forI manual oprations.
When it is possible to use Q?

This is very uncommon symbol and I don't know where this can be applicable.

Thank you.

It is just a manual override for the valve to allow manual checks of operation.


It can by useful if you are having problems with the valve not appearing to change position. Using the manual override it can help you diagnose if the fault is electrical or mechanical.

To add to Jonnie,

The closest thing I can find symbol wise is below...
https://www.parker.com/literature/L...000-2_Products/PDN1000-2US_Technical-Data.pdf

On the first page, in the middle there is "Manual - General Symbol" which looks like the |= shown in your picture.

@mikas_m: Just for the sake, this is my favorite place where you can find the best info about hydraulic&pneumatics, this is an ebook from them:
https://design.informabi.com/fluid-power-basics?code=UM_NX7UMB3

Thank you guys, very helpful. I'm now sure it's a manual override.
There is a number on the spool valve: 4WE6D51/AG23xxxx(unreadable), but I cannot find datasheet for it.
There is however one interesting thing. if I push it manually, I would expect the spring to return it to initial position, but this is not happening.
How to test if the spool valve is working (for example, what is active resistance to be expected If I measure with multimeter)?
I know also it is for max 31.5 MPa. What would be appropriate equivalent?

Thank you

You may have to contact Rexroth for the datasheet/info as that doesn't appear on their website.

31.5MPa is 315Bar or about 4500PSI