We are considering adding hydraulic variable rate to our JD1770 vacuum planter, pulled by a CaseIH Magnum 7120 & are concerned about whether we get enough hydraulic flow to make it work. We get along fine today with the 7120 & 1770 planter today without the hydraulic drive.

Does anyone have experience with variable rate & this combination?

Would it be possible / necessary to set the planter down early on the headlands (will be running Ag Leader SureStop row shutoffs) & delay the drive engagement somehow to separate the lift cylinders & the hydraulic drive motor?

I know the 1770 manual link would say you need 24.8gpm for lift cylinders in plant mode + 2-5gpm for the vac motor + 2-3gpm for the variable drive = 32.8gpm worst case
I would plan to wait to operate the markers (4gpm) until the planter is down.

Tractor Data link shows only 29gpm capacity

Also, I've been unsuccessful in finding a hydraulic schematic for the drive system. Can we plumb the drive motor downstream in series with the vacuum motor?

Thanks for any feedback!