[jdkskyking]

So Wanderlodges have this set up on the LXi models. They use a Chelsea PTO mounted to the Allison.
I am a bit confused as you are talking about a ZF gearbox, but your signature says Allison 4000 series. 

What is your fan hydraulic motor set up? Would think it’s a pilot operated bypass on the fan motor that is controlled by an external controller which receives its commands from the ECM. Actually just read through here and looks like your fan is just controlled by a DC solenoid, not a PWM from the ECM? 
So when you are talking about fixed displacement pumps and fixed displacement motors it’s actually quite easy to set them up. If they are fixed displacement, let’s say the pump is 1 cu inch displacement and the motor is 1 cu inch displacement then that means they will each spin very close to the same RPM. So now you can start doing a ratio to get the fan speed where you want it to be, generally limitation being max fan RPM. The fan manufacturer should be able to provide you with their max RPM, but actually more important is their desired RPM, which is where the fan is most effective. Some fans actually become less effective past a certain RPM, or a diminishing return let’s say. 
I have done quite a bit of research along with another one of our Wanderlodge members and we have upgraded our fan systems to make them more effective. We both went with a PWM controlled system, that can vary the speed of the fan based on an input signal. We are using a fairly accurate and reliable GM coolant sensor that sends its signal to a custom brain box, the box then tells the fan controller what to do with the fan via the PWM signal. PWM by the way is pulse width modulation, which is a fancy way of saying they basically switch the DC voltage to create a square wave form signal.

Hello Jeff, I guess I missed your reply, my apologies.

I’ve made a few changes since my last update.

I installed a standalone transmission cooler with a dual fan system. Initial testing is keeping transmission temperature just under 200°. Many will say the transmission needs the radiator to warm up. I don’t plan on operating the coach in extremely cold temperatures, it doesn’t take long to move the temp needle on the transmission.
The “divorce” of radiator/transmission initially is proving to allow the engine coolant/radiator to be less influenced by hot transmission fluid and vice versa. During the test drives the engine coolant is more stable however…

I took the bus to Caterpillar to have the cooling system evaluated. This was after I thoroughly flushed the entire system and a deep flushing of the radiator. 
The technician believes the engine coolant pump is operating normally. He agreed I need more airflow. Short term solution is a cooler thermostat. 

I replaced the fan blades with new ones and set the pitch to 27.5°. 
Currently, with my 210° thermal switch controlling hydraulic manifold solenoid I’m keeping the coolant temp below 215° during a long grade at 80° OAT. 

I’ve identified a Chelsea PTO and a EATON hydraulic pump. All on order… amazing how long it takes to get new items. 

Many projects underway. I replaced all of the aft control arms/bushings. Probably the only person on the planet that updated the Newell ZF suspension system on their own. Someday I’ll post about that endeavor. I have eight new bushings for the steer axle, I’ll eventually tackle that. 

Something else I’ve discovered is my C-13 compound turbocharger’s waste-gate has a diaphragm in the controller that allows close to 50 psi of boost. AdeptApe explained how to test this system by pinching off a line that controls the waste-gate. 
Doing so significantly improves performance of the turbocharger system. He pulled the original Caterpillar tests of my engine and it pulled 49 psi. Not many Newells with C-13s but this is go to know info for owners. 

So as I continue my efforts I’ll come back to your post for guidance. My plan for hydraulics was to utilize the existing hydraulic manifold to control the fan from the Allison transmission/PTO/hydraulic pump.

The engine driven VICKERS V20 will supply the ZF Steering Gearbox. Gearbox has internal pressure relief system so the plumbing will be relatively simple. The hydraulic manifold steering gearbox line will return to tank so the fan circuit will be the only work being done. 

Yes I reference ZF gearbox, I failed to include “steering”.

Please shoot holes in my theory. I’ll take any and all advice about this journey. 

One last thing, anyone with an aging ZF suspension… don’t forget to have your ZF RAS pressure accumulator serviced. If your accumulator pressure leaks down, life will be miserable with a “floating” tag axle. Newell has added the system to their PMI. 
JK