[hypoxia]

Called Newell, they use TES-295 Mobil Delvac 1 ATF in the RAS system.  They also loan out their hydraulic charging station!  Said it weighs 60-80# so the shipping would be up there.  I stopped at a hose supply, they said the threads on the hydraulic block are 16mm X 2.0 and to be very careful if using a high pressure pump since it could easily over pressurize the system.  Hydraulic pump on order.  Accumulator order was cancelled by Find it Parts, their source would not ship them since they are pressurized.

[jdkskyking]

The accumulator I ordered from FinditParts has been cancelled by them and my money returned. Apparently they can not get accumulators.
Not good…

[jdkskyking]

Found this document tonight. 

Centering Cylinder Function.pdf Size: 73.89 KB  Downloads: 8

My gut tells me not to overthink the rear cylinder. 
It is critical that the forward and rear cylinders are synchronized using the gauge tools and that there is no air anywhere in the system. 
Beyond that, one side does the turning, the other is a damper. The accumulator maintains equal pressure in all four chambers when the forward master cylinder is in the straight forward position. In the straight forward position the entire system is in equal pressure.
Axle caster and tires toe-in, help center the axle to go straight forward when the turning is done.  My opinion.

REVISION - NEW INFORMATION 

BOY WAS I WRONG… NOT A DAMPENER AT ALL… THE DESIGN ABSOLUTELY HAS A CENTER-POINT AND THE CYLINDER KNOWS WHERE IT IS.

CENTERING CYLINDER IS AN UNDERSTATEMENT. YES, THE CYLINDER WILL SEEK TO CENTER THE TAG AXLE AND INFLUENCE THE STEER AXLE AS WELL. 

IN A NUT SHELL, WITH THE WEIGHT OFF OF THE TAG TIRES AND THE STEERS ON PADS, I STARTED THE ENGINE AND TURNED THE STEERING FULL LEFT AND SHUT OFF THE ENGINE. 
IMMEDIATELY THE THE STEERING WHEEL WANTED TO ROTATE BACK TO THE RIGHT. WHEN I FINALLY LET GO OF THE WHEEL, IT ROTATED RAPIDLY BACK TO CENTER. I PERFORMED THE SAME EXERCISE TO THE RIGHT WITH THE SAME RESULTS. 

I WILL POST MORE INFORMATION ABOUT THE OLD CYLINDER I DISASSEMBLED. I WILL NOT ATTEMPT TO EXPLAIN HOW IT WORKS. I’TS PFM TO ME?.

[hypoxia]

The accumulator I ordered from FinditParts has been cancelled by them and my money returned. Apparently they can not get accumulators.
Not good…

They are available but since they are pressurized they are Hazmat.  I understand that...  I was told the ones Newell is ordering now are not pre charged and that they will do that.  I have Nitrogen so that is not a factor here.

[jdkskyking]

ZF Rear Centering Cylinder disassembled. 

   

[hypoxia]

I just realized the fluid used in the RAS, Mobil 1 Delvac ATF is TES-295 the same as used in the hydraulic system and transmission so I added that to my post on the fluid.

[hypoxia]

I ordered an Accumulator which should arrive in a couple of days.  There was a Hazmat shipping charge.  Currently promo code SPRING24 gets 10% off. 

[hypoxia]

Accumulator arrived from Iron Wing Sales, it's the same part with the VOLVO 3987649 Label which is one of the cross reference part numbers on the Bosch list.  Still waiting for the pressure sending unit.
   

[jdkskyking]

Jim,
Once you removed the label does the bottle have the same data stamped on it? 
My gauge set arrived. 
I just ordered the accumulator. 
Great to have options. 
JK

[jdkskyking]

Food for thought. 

           

I had a local hydraulic shop put this together for me. 

It’s for the rear centering cylinder chambers that always have accumulator pressure, the two lines farthest from the actuator rod. 

Most coaches have four hydraulic lines running from the hydraulic manifold down the rear cylinder. 
Only three are necessary. 
This setup includes a bleed valve. 

When I decide to do this mod I’m also going to add a bleed valve at the accumulator connection.