Determining valve type from drawings

[Steve_112]

I'm having some difficulty determining which type of valves the following are.
I believe the first 1 is a pressure relief valve. However i don't understand the sectioning philosophy, some things just aren't sectioned that i'd expect to be, therefore I'm finding it hard to gauge which surfaces contribute to the opening force.

As for the second one it seems its a flow control valve, but i don't know what is happening in section B.

Any help would be appreciated, thank you.
Steve

 

[Q_Goest]

Hi Steve. The first one is a pressure relief valve as you say. It's a cartridge type that screws into a manifold block similar to the manifolded set of valves in the block below it. Port P is your inlet, high pressure port and port T is your discharge, lower pressure port. The poppet is shown directly below the letter T and discharge pressure is acting on the back of the poppet, tending to close the valve along with the spring. Inlet pressure from port P is acting on the underside (left side) of the poppet tending to open the valve. I would assume these are all hydraulic cartridge valves.

The second one is some sort of flow control valve as you know. The top most hole is shown in the left hand view with what appears to be an orifice screwed into it. The section is looking just past that so they don't show the orifice. There's a vertically drilled hole that you can't see in the left hand view because it's just below the plane that the view is sectioned from. That verticle port is shown in section B-B and connects the top most hole to the hole leading to the valve shown in section B-B. Note that the valve shown in section B-B is above the plane that the left hand view has been sectioned in so you won't see that valve in the left hand view. But you do see the port labled A in section B-B - that's the circular hole that the section line is running through just below that orifice. In section B-B, you have letter T showing the port T in the left hand view. And the lower most hole in section B-B is the lower most port running horizontally in the left view that has a valve on the left and port P on the right. Note that there are no hidden lines being shown in either of the views because those hidden lines would only make it more difficult to decipher the drawing.

 

[Steve_112]

Thanks very much for the quick response, i just have a couple of questions.
Is the 2nd valve pressure compensated, i can see that if the pressure on port P was to rise we could move the spool and waste flow to the reservoir, but what about A. Would we move through the valve in section B to relieve flow to the tank and thus maintain a constant pressure.

As for the 1st valve, is the active surface the black arrow, if so what are the roles of the red and yellow surfaces.

Sorry for a lot of questions drawing interpretation has never been my strongest point.

Thanks,
Steve

 

[Q_Goest]

Hi Steve. I don't know what all the valves do as a set. I'm not that familiar with this particular valve either. Regarding the small bit on the end of the relief valve, I'd assume that's just for guidance of the poppet. It's probably just a bushing to keep the poppet centered and only allows movement in the axial direction.