That is the pressure valve ( like a bike tube air valve. The cap pops off and if you look at the electric pressure switch the air pressure is set at 2 lbs less the the cutoff pressure. You can use a tire pressure gauge to check the pressure. If you believe that your water pressure is good at the...
Not sure if you bought your JD tractor yet but my sister inlaw is selling my brother Mikes tractor 2320. He had a stroke and has cancer and no longer can use it. Front loader, deck , ballast box. Located in Michigan. 1069 hrs