I thought anything other than a 3 position was regenerative?
Four position is both which is why it is preferable. My understanding from discussions on this forum is the Kubota four position valves function as follows:
Position 1 - neutral tandem center - both work ports blocked and pump unloaded to HPCO
Position 2 - Pump to cylinder, cylinder to tank
Position 3 - pump to cylinder, with cylinder regenerative loop
Position 4 - pump to cylinder, cylinder to tank.
The only position that is using cylinder regeneration is position 3 which is "fast dump". When you go past that to position 4 you have normal speed cylinder/motor control. With the 3 position valve your only have regenerative dump which will not work with a motor.
Dan