Water tanker valve

[grassfarmer]

I have a portable water tank (1800 litre)that I use to water small lots of cattle on rotational grazing. I have a small trough mounted on the back about 12"w x 18"l x 14"d and have trouble getting a suitable valve for it. I have tried the Hudson valves that we use on our pipelines but it only fills a drip at a time. I have tried the cheap UFA valves that you are meant to screw a garden hose into but although they fill quicker they tend not to seal resulting in a steady drip. Does anyone have a suggestion of another type of valve? I want high volume, gravity fed from a valve that is physically small enough to fit in my trough. Thanks in advance.

[grassguy]

Could a Gallagher valve work? They have a float attached to the valve by a piece of string, might be able to withstand the cows pushing it around, valve would be down near the bottom of the tank.

[Eastcoaster]

The Gallagher valve works good for me,but it is used in an old bathtub which has more space for the float which may be a problem for you with the smaller tank. Possibly a smaller float with it may be able to be geared up. They do have good flow rate and shut off good.

[dalek]

I'd try making one. I've seen them made with a 2" PVC pipe going to a 4" with a rubber ball in it, just have to look around to find a ball with the right diameter.