Screws on piston valves

[Gun Freak]

I see some people put screws around the pilot side of barrel sealing piston valves housed in a T. Why is this?

[Demon]

To make them servicable or more compact i think

[deathbyDWV]

Yep it's to keep them more compact but also servicable...

[MrCrowley]

Yup, both of the above. Especially on larger cannons where having a huge adapter that the piston can fit through adds a lot of pilot volume, weight, looks bad, etc.

[Gun Freak]

Hmmm..... I still don't understand why the screws are necessary.

[MrCrowley]

Hmmm..... I don't understand why the screws are necessary.

Because the piston can't fit through a plug/bushing. So if the piston doesn't work (like yours ), you can unbolt the plug and fix the piston. The plug/bushing isn't glued in so it needs bolts to hold it in. You also have to seal it with an o-ring which can be a bit tricky.

Sometimes people like sgort87 or Joel at Spudtech, prefer to have a compact valve, and you can't do that with normal fittings while being able to service the piston.

[Gun Freak]

OHHH. So the piston is housed inside the plug, right? You think that could work on only a 1" Tee? I am upsizing my housing from 3/4 to one inch for better flow... maybe that will help reduce pilot volume and make it serviceable.

[MrCrowley]

OHHH. So the piston is housed inside the plug, right? You think that could work on only a 1" Tee? I am upsizing my housing from 3/4 to one inch for better flow... maybe that will help reduce pilot volume and make it serviceable.

Huh? No...it's housed inside the tee.

You can make a compact, bolt piston housing in any size. These days it's mainly done for compactness as you can easily find and use threaded fittings to service the piston. Only down side with that is they usually make it less aesthetically pleasing, less ergonomic and less compact.

[Gun Freak]

I meant it slides in the plug. Jeez i'm retarded. Ok I'm just sticking with the old design. Just upping the size.

[mark.f]

Most pistons I've seen don't slide inside of a plug, but slide inside of a piece of pipe also glued in the tee.

On valves made with special materials and tighter tolerances (like the Supah valve), the piston simply slides in the tee's socket itself, though this could prove difficult to do without the proper tooling (though certainly not impossible).

And, like they said, the screws are to hold in the plug. One could simply use a female adapter and threaded plug as well, but these get expensive as size goes up, and adds pilot volume and overall valve size.

[Gun Freak]

K thanks Mark. Exactly the answer I was looking for.