I have a Kubota L2501, with the 4WD HST,. You have to engage the clutch, before you flick the PTO on..
I don't know about Kubotas as I have a Deere.
But a HST or Hydrostatic transmission, at least the Deere I have does not have a clutch.
You shift the tractor into what speed range you want then press the forward or backward pedal and your off.
As far as the PTO all I have to do is pull the PTO knob out and its working.
To run the PTO when I'm not on the tractor (when using a chipper for example) I have to set the parking brake then it'll run when I jump off the seat. If I don't set the parking brake getting off the seat will kill the tractor.
How does this clutch work on a Kubota with a HST?