Question - New Holland TN75DA Hydraulics

   / Question - New Holland TN75DA Hydraulics #1  

jc_hudson

New member
Joined
May 21, 2024
Messages
4
Tractor
New Holland TN75DA
Hey everyone, looking for some help understanding the hydraulic arrangement on my TN75DA. Tractor currently has 2 Mid-Mount valves for the FEL that are controlled via joy stick and 2 rear remotes that are controlled via two separate levers (both are dual action, top valve has float).

My ultimate goal here is to tap into the high pressure circuit to power a hydraulic top link via a 12V dual solenoid valve. Short of taking things apart and testing/exploring, I have exhausted all of my resources trying to figure it out definitively from the service manual and parts diagrams.

Main questions:

  1. In the pictures, am I correct in my understanding of the high pressure flow?
  2. If yes to #1, is it feasible to tee into the port for the lift control valve as shown in picture #4 for the top link valve?

Attachments:
  1. Marked up picture of rear remotes
  2. Hydraulic System Diagram from the service manual
  3. Page from the service manual describing the hydraulic system
  4. Marked up picture with proposed plumbing arrangement
  5. Page from service manual detailing the aux. valve block & lift control valve

Any input will be greatly appreciated!


H1.jpg


H2.jpg


H3.jpg


H4.jpg


H5.jpg
 
   / Question - New Holland TN75DA Hydraulics #2  
I believe you're correct on identifying the line that feeds the 3 pt hitch, however, you can't Tee pressure lines on open center hydraulic systems.

Doing so, means the fluid will take the path of less resistance. What would happen is that every time you wanted to adjust the top link, the fluid would just go through the 3 pt valve because that's the path of less resistance.

What you need to do, is to take that line out. Run a new hose to the new valve. And then another hose from the new valve back to the 3 pt valve to feed it. Make sure you get a valve that can handle the flow of the tractor and that can handle high pressure on the Tank port.
 
 
Top