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Air Dryer

Hi everyone just had the air dryer replaced 93 GV DD now the cutoff on the air gauge is 130 prior it was 110 is 130 too high? So air pump on at 90 off at 130.

Thanks
Woodie
Woodie Lee Jr
93 U300. 40'
6V92ta

Re: Air Dryer

Reply #1 –
That is not to high. You should have better brakes with the higher pressure.
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: Air Dryer

Reply #2 –
As I understand it, Air Pressure RELEASES the brakes, Spring pressure applies them. So, higher pressure just means release faster if anything.
Future Foretravel Owners
2019 Jeep Cherokee Trailhawk
Retired USAF, Retired DOD Civ's
FAA A&P, Indust. Eng., Acft Depot Lvl. Maint.
Larry and Becky Rountree

Re: Air Dryer

Reply #3 –
Quote from: master2301 –
As I understand it, Air Pressure RELEASES the brakes, Spring pressure applies them. So, higher pressure just means release faster if anything.

Yes and no.

Yes PARKING/EMERGENCY BRAKE is spring applied, air released.  But suspect little difference between 100 and 130 PSI for overcoming spring pressure.

SERVICE BRAKES  are air applied.  So, more air pressure means more braking for the same amount of pedal pressure.
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: Air Dryer

Reply #4 –
And then only thing that makes the brake pedal hard to push down is the little spring under the pedal. So, increasing the pressure from 100 to 130 won't make any difference in the pedal effort.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Air Dryer

Reply #5 –
Quote from: master2301 –
As I understand it, Air Pressure RELEASES the brakes, Spring pressure applies them. So, higher pressure just means release faster if anything.
Our coaches are equipped with spring brakes on the rear brakes only. When the air is exhausted the spring cans apply parking break pressure. Nothing like applying the brakes. If you are rolling slowly and set parking brake you will slow to a stop. The air pressure applied when the parking brake is released pushes against one of two diaphragms to collapse the spring.  It stays this way the entire time you are driving. It does nothing else till the parking brake is set releasing air.  Just a couple of psi on the service brake chamber will fully extend a unloaded cylinder. I was amazed at how little pressure it takes. Higher available brake pressure would be okay with me, however compressor life is reduced do to operating at higher loads/pressure.
Scott

Re: Air Dryer

Reply #6 –
I run mine at 125-130 also. It does stop better. You will find more leaks.

Re: Air Dryer

Reply #7 –
Quote from: Pierce & Gaylie Stewart –
And then only thing that makes the brake pedal hard to push down is the little spring under the pedal. So, increasing the pressure from 100 to 130 won't make any difference in the pedal effort.

Pierce

Yes, I should have stated it more clearly.

The pedal pressure to achieve a given amount of brake pedal deflection will be the same.  And the the opening of the valve sending air to the service brakes will be the same if the same amount of pedal deflection.

But, at higher air pressure, that same opening of the valve apply more force to the brakes, so the brakes be applied HARDER.

So, it would not take as much pedal deflection/pedal effort to achieve the same amount of braking.
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: Air Dryer

Reply #8 –
I'm a little skeptical about 120 vs 130 psi in our tanks and having better brakes. Yes it may feel that way because the distance your pushing the pedal. Normal stopping brake application is probably under 20 lbs. Under extreme or emergency stopping you may apply to full application but you would never hold this unless you  were headed for a brick wall.  Something is out of adjustment or there is a defect in your braking system if feel you have better brakes with 130 or more psi.
Doug W.
96 36' U270 CSGI #4946
04 Toyota Tacoma 4x4
PNW

Re: Air Dryer

Reply #9 –
I agree.  I am NOT suggesting an increase from OE governor PSI setting. In the 150,000+ miles we drove our Foretravel, the factory set pressure was just fine.

Just trying to address the question being discussed.
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: Air Dryer

Reply #10 –
Changing the subject a little-- what is the part number for the park brake valve on the dash?
Chris
1999 U 320 DGFE
Build Number 5523
Chris & Elka Lang
In the field, Lonoke AR