[jdkskyking]

Yep, I just verified accumulator pressure. Still holding steady at 15 bar.

There are several steps we can take to improve our ability to bleed the system of air by adding bleed valves in certain locations. I stand by my concern that the master cylinder can’t be bled unless the hydraulic connection ports are as close to 12 o’clock as possible. ZF specifically states that if the cylinder can’t be oriented properly then the cylinder must be bled properly then installed in its operating location.

I have both cylinders internal pieces and don’t believe that flowing fluid through the system using the MINIMESS fittings will rid the system of all air unless bleed valves are installed at key locations such as at the accumulator top, rear cylinder side that centers the tags, and the front cylinder’s ports. By adding additional MINIMESS and using a multi step process of bleeding, there is a better likelihood of ridding the system of air. 

My front cylinder was re-oriented and the system has been serviced so many times that it might have less air in the system than before. I’m happy with the current performance but the game changer was getting all three axles working together. 
All the accumulator does is ensure there is ample pressure in the system to keep the TAG straight going down the road. That a simplistic statement but and yes there’s benefits when the rear tires work in concert with steers while maneuvering but if you don’t have a good straight ahead rolling bus… the rest is useless.  

We’ve figured out the ZF RAS mysteries and now the mission will be improving our system.

[jdkskyking]

I see the nitrogen pressure should be 10 bar, 145 PSI and hydraulic pressure should be 15 bar, 217 PSI according to page 11 of the attached ZF Servocom RAS manual.  Is this the wrong manual?

(Eventually I had Newell set my hydraulic pressure to 15 BAR per ZF. The system has been working perfectly. I was told the 275 psi was a mistake. I was also told the 250 psi is used because of leak down. I disagree otherwise the pressure sensor would not be 230 psi. I will eventually need to install a pressure sensor of around 200-210 psi. I believe there are failed pressure sensors because there is not an isolation valve to protect the sensor during the process used to pressurize and bleed the system.)

[hypoxia]

I see the nitrogen pressure should be 10 bar, 145 PSI and hydraulic pressure should be 15 bar, 217 PSI according to page 11 of the attached ZF Servocom RAS manual.  Is this the wrong manual?

(Eventually I had Newell set my hydraulic pressure to 15 BAR per ZF. The system has been working perfectly. I was told the 275 psi was a mistake. I was also told the 250 psi is used because of leak down. I disagree otherwise the pressure sensor would not be 230 psi. I will eventually need to install a pressure sensor of around 200-210 psi. I believe there are failed pressure sensors because there is not an isolation valve to protect the sensor during the process used to pressurize and bleed the system.)

I pressurized to 16 bar 232 PSI (ZF Specifies 15 +1/-3 bar) and adjusted the Noshok 300L pressure switch to around 170 PSI.  The dash light did not come on when I depressurized the system.  It turned out  the wires on the DIN plug were connected to terminal 2 & 3 which is Normally Open.  I changed it to terminal 1 & 3 Normally Closed, now the dash light illuminates below ~170 PSI ~12 bar.

[[email protected]]

I was able to find and purchase the links for the sway bar but have not been able to
find the 2 steering links for the front steer axle. I have coach 752 2005.

Thanks

[jdkskyking]

Contact:

Jessica Taylor

Precision Transmission

(239) 693-7477

She can work with Corletta Davis at ZF to help you find the entire ZF Sway Bar Link assemblies.

Tell her to review the order for Jeff King

[jdkskyking]

Quick update/reminder about my ongoing project. 

It’s been many years since I started this journey and I’m starting to bring it all together.

The project will resolve several intertwined problems and challenges.

My 2005 Newell with a Cat 13 ACERT and Allison 4000 transmission. 

A single hydraulic pump, VICKERS V20 to supply the ZF Steering Gearbox and Cooling Fan Hydraulic Motor. 

FACT: The V20 does not provide the hydraulic system with the needed flow to operate the two components. 

Resolution: Split the system. The engine driven VICKERS V20 supplies the ZF Gearbox only. 
Add a hydraulic pump for the cooling fan hydraulic motor circuit driven by a transmission mounted PTO. 

I’m getting closer to achieving my goal. 

   

   

The WHY…

In reality, the ZF Gearbox needs a dedicated hydraulic pump (flow) to function “properly”. What is properly? Continuous hydraulic flow irregardless of the wants and needs of a cooling fan circuit… I’m confident the ZF Gearbox performance, the “feel” going straight forward will improve… less hunting… 

In reality, the cooling fan blades need to be “pitched” properly to draw air through the radiator stack and provide enough airflow through the engine bay and out the rear hatch to prevent excessive heat buildup. Final blade pitch will be 30° up from the original setting of 20° (due to the limitations of a single hydraulic pump expected to serve two systems). 

Theory and Reality… Pain and Suffering… Practical Application…

The $tory of my Journey… 

Live and Learn 

More to come. 
JK

[arcticdude]

Are you using a wet spline pto or a greased spline?

The greased spline on some Birds has a “fretting” issue that damages the splines. Supposedly a wet spline system doesn’t experience fretting issues. I don’t know if any owners have had a wet system long enough to actually test that theory of wet splines being better.

Frequent greasing can also reduce the damage, though the interval bantered about is 3500 miles for routine greasing.


I must add the units affected so far are all Series 60/Allison combos, while none of the C-13/Allison units have yet to show any fretting occurring.

[jdkskyking]

Yes sir. 

Chelsea 267 PTO with a wet spline setup. Taps off of a transmission sump pressure source to the PTO case and then up to the flange. 

   

A friend had a CC with the same PTO and pump. His was mounted in a completely different position than I could because there was only six flange/bearing cover mounting position. 

In the end my pump will be inverted. I’m guessing the grease flange is a different configuration. 

DANFOS/EATON X20 421AK00110C pump.

[arcticdude]

Sounds like you’ve got a great plan going. It will be great to hear your results!