What does this knob do on my Hinomoto do?

[Lagonia]

I got my tractor (first tractor) a few weeks back. Happy so far but I am new to tractors as well. There is a knob under the seat that I do not know what it does. It gos to, what appears to me to be the differential. Picture attached.

BTW, this is a Hinomoto N239

 

[groundcover]

My guess is it controls the speed of the 3pt hitch.

 

[dex3361]

I agree with groundcover.

 

[California]

On many tractors, a knob like that closes the drain-down line from the 3-point. You close it to leave an implement suspended in the air indefinitely.

I'm guessing this applies to Hinomoto too.

 

[Gary Fowler]

YEP, controls the rate of fall for the 3 ph. Dont close it down all the way or the 3 ph wont raise either. Been there, done that accidentally and took a while to figure out why the 3 ph would not raise. Finally heard the hydraulic pump relief valve squealing and figured it out. Never did figure out how the valve got screwed all the way in though.