</font><font color="blue" class="small">( He said something about disks inside the hydrolics/transmission and with no hydrolics the disk plates would lock up hence, locking up the drive train. The possible condition, he explained, was that your basically driving along and if the hydrolic system fails.... your stuck, no pushing the tractor like a manual transmission. )</font>
Kubota hydrostatic transmissions are basically an integrated
variable displacement hydraulic pump and motor. The motor
drives a conventional multi-gear transmission which also
allows the gears to disengage in the neutral position.
Thus even in the case where the hydraulic motor somehow
managed to lock-up, the motor shaft would be disconnected
from the rear differential in neutral.