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Topic: Pressure reducing valve? What is this for? (Read 531 times) previous topic - next topic

Pressure reducing valve? What is this for?

When my coach builds air past 110 psi, this starts to leak air. What is it? A regulator/reducer of some sort? It seems to be tied to the throttle system, so I'm just curious how all these parts play together and what I am looking at.
1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Pressure reducing valve? What is this for?

Reply #1 –
That is a pressure regulator that lets you control the outlet pressure. You might be able to disassemble it and replace an O ring or seal instead of changing out the valve. I have no idea of how it would control the throttle. Protech racing might know as he has a similar coach.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Pressure reducing valve? What is this for?

Reply #2 –
Quote from: craneman –
That is a pressure regulator that lets you control the outlet pressure. You might be able to disassemble it and replace an O ring or seal instead of changing out the valve. I have no idea of how it would control the throttle. Protech racing might know as he has a similar coach.

I don't mind replacing it, My local fleet store has one but it's set to 70psi by default while the one that is on there defaults to 60 psi. I'm trying to figure out how accurate i need to be here... do I need to buy a T fitting and put a gauge on it to make sure I am at 60 psi?
1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Pressure reducing valve? What is this for?

Reply #3 –
I think that it's the pressure regulator for the cruise .  Might be throttle.
Either way I don't think that mine leaks.  But never really looked at it over 110 psi. 

Re: Pressure reducing valve? What is this for?

Reply #4 –
I would say not.  Just change it and see if the cruise works. 
My cruise goes WOT , so I have not used it lately :)
I believe that I have a faulty speed input box. Thus the GPS Speedo

If the cable coming out of that box,  goes to the throttle and is slotted.  It's cruise.

Re: Pressure reducing valve? What is this for?

Reply #5 –
It is super loud once it starts leaking. I am pretty sure the previous owners Mechanic just dialed back the governor to hide the leak. I haven't been able to build pressure over 105 and I recall the Mechanic saying he had dialed it back from the default setting when I was inspecting the coach. I have seen some other shotty things around work he supposedly did, which is why I'm just trying to start fresh with known good parts.
1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Pressure reducing valve? What is this for?

Reply #6 –
Quote from: Protech Racing –
My cruise goes WOT , so I have not used it lately :)

One easy to check cause of cruise going to WOT or not returning to lower throttle positions after even a brief WOT is a clogged exhaust port in the Bendix module.  Remove the exhaust port and check for debris.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Pressure reducing valve? What is this for?

Reply #7 –
I don't know about Mike's coach, but Elliott's photos show a Bendix cruise control/air throttle panel.  Different from King Control.

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Pressure reducing valve? What is this for?

Reply #8 –
Quote from: Chuck & Jeannie –
I don't know about Mike's coach, but Elliott's photos show a Bendix cruise control/air throttle panel.  Different from King Control.
Chuck this is awesome stuff, thank you. Very informative in general but also directly answers my question about 60 vs 70psi

1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Pressure reducing valve? What is this for?

Reply #9 –
I've posted lots of various notes about our Bendix system over the years.  A search on the Forum will pull them up.  For instance:

air throttle problem

Williams Controls WM453109 Air Throttle Valve
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Pressure reducing valve? What is this for?

Reply #10 –
Quote from: Chuck & Jeannie –
I don't know about Mike's coach, but Elliott's photos show a Bendix cruise control/air throttle panel.  Different from King Control.

Thanks, Chuck.

Small brain f....t.

Yes, I meant Bendix cruise just as pictured in your post above.

I will go back and correct my post as well.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Pressure reducing valve? What is this for?

Reply #11 –
That is called an inversion valve and splits the pressure between the cruise control and the throttle
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins
 

Re: Pressure reducing valve? What is this for?

Reply #12 –
Quote from: red tractor –
That is called an inversion valve and splits the pressure between the cruise control and the throttle
The leaking device in Elliott's original post is a RV-1 Reducing Valve.

I'm not sure what "That" refers to, but to expound a bit on this point about the Inversion Valve, please refer to the diagram I posted in Reply #7.

The TR-3 Inversion Valve shares two pressure inputs - one from the Brake Valve and the other from the CA-1 Control Module.

The DC-4 Shuttle Valve shares two pressure inputs - one from the Throttle Valve and the other from the TR-3 Inversion Valve.

The purpose of the DC-4 Shuttle Valve is to select which pressure input controls the CC-5 Air Cylinder.  The CC-5 Air Cylinder, of course, moves the fuel lever on the engine.

When the Bendix Cruise Control is engaged, the CC-5 Air Cylinder is controlled by the CA-1 Control Module pressure output, which passes through the TR-3 Inversion Valve and the DC-4 Shuttle Valve.  This control can be interrupted in one of two ways:

1.  If the Brake Valve is opened (brakes are applied) it sends pressure simultaneously to the TR-3 Inversion Valve and to the Stop Light Switch.  The Stop Light Switch sends a signal to the CA-1 Control Module which cancels the Cruise Control "SET" signal.  At the same time, the TR-3 Inversion Valve vents pressure from the air line going to the DC-4 Shuttle Valve.  This, in turn, allows the spool inside the DC-4 to shift, which allows the Throttle Valve to assume control over the CC-5 Air Cylinder.

2.  If the Throttle Valve is opened (throttle pedal pushed down) to a point where the pressure in Air Line #11 exceeds the pressure in the air line going from the TR-3 Inversion Valve to the DC-4 Shuttle Valve, then the sliding spool inside the DC-4 will shift, control of the CC-5 Air Cylinder will be assumed by the Throttle Valve, and the vehicle speed will increase above the Cruise Control set point.  When the Throttle Valve opening is reduced (throttle pedal let up) pressure in Air Line #11 is reduced to less than pressure in line from the TR-3, the spool inside the DC-4 shifts, and the CA-1 again assumes control of the CC-5.

Cheers!
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"