Air pressure SP36

[williamcharrison]

I was waiting in line on a slight grade at a Flying J with my
foot on the brake (probably 1 minute) and I noticed quite a drop
in air pressure and then my steps came out. I set the parking
brake until pressure came back up and the steps retracted.
Is this normal, and if not, what corrective action need I take?

Chuck Harrison
Akron, Ohio
90SP36

[Pete Masterson]

No, it is not normal. You have an air leak. Below is an excerpt of
the Air Brake Check from the California Commercial License DMV
booklet. While this test isn't required for RVs, it is a good test of
what's considered safe in an air brake system. Note that the fully
charged system should not lose more than 3 psi in one minute with the
brakes held on. It's time for some serious examination of your air
system.



In-Cab Air Brake Check

NOTE: All items marked with an asterisk (*) are critical parts of the
in-cab air brake test and must be demonstrated during DMV testing.
They may be performed in any order. If these items are not performed
correctly, it is considered an automatic failure of the pre-trip test.

Test air leakage rate. (* second test only)

* With a fully-charged air system (typically 125 p.s.i.), turn off
the engine, release the service brake (brakes off), and let the
system settle (air gauge needle stops moving). Time the air pressure
drop. The loss rate should not be greater than:
— 2 p.s.i. or less in one minute for single vehicles.
— 3 p.s.i. or less in one minute for a combination of two vehicles.
— 5 p.s.i. or less in one minute for a combination of three or more
vehicles.
If the loss is too much, check for air leaks and fix.

* With roughly a fully charged air system (typically 100-125 p.s.i.),
turn off the engine. Release all brakes and allow the system to
settle (air gauge needle stops moving). Then apply full steady
pressure to the brake pedal (brake on) and hold. After the system
settles again, the air loss should not be more than:
— 3 p.s.i. or less in one minute for single vehicles.
— 4 p.s.i. or less in one minute for a combination of two vehicles.
— 6 p.s.i. or less in one minute for a combination of three or more
vehicles.
If the air loss is too much, check for air leaks and fix. For testing
purposes, identify if the air loss rate is too much.



Pete Masterson

'95 Blue Bird Wanderlodge WBDA 42

El Sobrante CA
aeonix1@...



On Aug 10, 2007, at 8:43 AM, williamcharrison wrote:

> I was waiting in line on a slight grade at a Flying J with my
> foot on the brake (probably 1 minute) and I noticed quite a drop
> in air pressure and then my steps came out. I set the parking
> brake until pressure came back up and the steps retracted.
> Is this normal, and if not, what corrective action need I take?



[Non-text portions of this message have been removed]

[Howard O. Truitt]

Chuck,
Losing air that fast is not normal check for an air leak. The operation of the
step as you described is normal at least that is the way my step works. If it is
not normal then we are both abnormal and I have been accused of that for years.
Howard T., Sowega, 86 PT40

----- Original Message -----
From: williamcharrison
To: WanderlodgeForum@yahoogroups.com
Sent: Friday, August 10, 2007 11:43 AM
Subject: [WanderlodgeForum] Air pressure SP36


I was waiting in line on a slight grade at a Flying J with my
foot on the brake (probably 1 minute) and I noticed quite a drop
in air pressure and then my steps came out. I set the parking
brake until pressure came back up and the steps retracted.
Is this normal, and if not, what corrective action need I take?

Chuck Harrison
Akron, Ohio
90SP36






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[Non-text portions of this message have been removed]

[pattypape]

This is not good , step extends at a low pressure of about 65 psi.
There is a big air leak someplace,
Spring brakes will soon lock up the rear wheel brakes at a low psi.

Bill 88 FC Michigan


--- In WanderlodgeForum@yahoogroups.com, "williamcharrison"
wrote:
>
> I was waiting in line on a slight grade at a Flying J with my
> foot on the brake (probably 1 minute) and I noticed quite a drop
> in air pressure and then my steps came out. I set the parking
> brake until pressure came back up and the steps retracted.
> Is this normal, and if not, what corrective action need I take?
>
> Chuck Harrison
> Akron, Ohio
> 90SP36
>

[Bob Lawrence]

The rear spring brakes lock up at 60psi per DOT. You probably have the
rubber valve torn in the can.
I just replaced both of mine (no problems, just precaution). The now
have double cans to put on so you have a backup.
When driving my 18 wheeler a couple of years ago going down a mountain
ineastern Washington, one of the cans on the tractor sprung a leak and
every time I put on the brakes, you could hear the hissing. Managed to
make it down by really relying on the jake brake. Had it changed out on
the side of the road.
It is not a big job, but I wouldn't try it yourself as the brake can
spring needs to be caged to release the brake.
Drive slowly to a truck place or have them come out to you.
Bob Lawrence
84 PT36
Tacoma, Wa.

>
> I was waiting in line on a slight grade at a Flying J with my
> foot on the brake (probably 1 minute) and I noticed quite a drop
> in air pressure and then my steps came out. I set the parking
> brake until pressure came back up and the steps retracted.
> Is this normal, and if not, what corrective action need I take?
>
> Chuck Harrison
> Akron, Ohio
> 90SP36
>

[williamcharrison]

Hi Bob,
The cans you mention, are they the brake actuators located outside
the rear wheels?
Chuck Harrison
Akron, Ohio
90SP36

--- In WanderlodgeForum@yahoogroups.com, "Bob Lawrence"
wrote:
>
> The rear spring brakes lock up at 60psi per DOT. You probably have
the
> rubber valve torn in the can.
> I just replaced both of mine (no problems, just precaution). The
now
> have double cans to put on so you have a backup.
> When driving my 18 wheeler a couple of years ago going down a
mountain
> ineastern Washington, one of the cans on the tractor sprung a leak
and
> every time I put on the brakes, you could hear the hissing. Managed
to
> make it down by really relying on the jake brake. Had it changed
out on
> the side of the road.
> It is not a big job, but I wouldn't try it yourself as the brake
can
> spring needs to be caged to release the brake.
> Drive slowly to a truck place or have them come out to you.
> Bob Lawrence
> 84 PT36
> Tacoma, Wa.
>
> >
> > I was waiting in line on a slight grade at a Flying J with my
> > foot on the brake (probably 1 minute) and I noticed quite a drop
> > in air pressure and then my steps came out. I set the parking
> > brake until pressure came back up and the steps retracted.
> > Is this normal, and if not, what corrective action need I take?
> >
> > Chuck Harrison
> > Akron, Ohio
> > 90SP36
> >
>

[Bob Lawrence]

Why yes, they are. Easy to spot, only round cans inboard of rear
wheels.Bob Lawrence
84 PT36
Tacoma, Wa.
>
> Hi Bob,
> The cans you mention, are they the brake actuators located outside
> the rear wheels?
> Chuck Harrison
> Akron, Ohio
> 90SP36
>
> --- In WanderlodgeForum@yahoogroups.com, "Bob Lawrence"
> wrote:
> >
> > The rear spring brakes lock up at 60psi per DOT. You probably
have
> the
> > rubber valve torn in the can.
> > I just replaced both of mine (no problems, just precaution). The
> now
> > have double cans to put on so you have a backup.
> > When driving my 18 wheeler a couple of years ago going down a
> mountain
> > ineastern Washington, one of the cans on the tractor sprung a
leak
> and
> > every time I put on the brakes, you could hear the hissing.
Managed
> to
> > make it down by really relying on the jake brake. Had it changed
> out on
> > the side of the road.
> > It is not a big job, but I wouldn't try it yourself as the brake
> can
> > spring needs to be caged to release the brake.
> > Drive slowly to a truck place or have them come out to you.
> > Bob Lawrence
> > 84 PT36
> > Tacoma, Wa.
> >
> > >
> > > I was waiting in line on a slight grade at a Flying J with my
> > > foot on the brake (probably 1 minute) and I noticed quite a drop
> > > in air pressure and then my steps came out. I set the parking
> > > brake until pressure came back up and the steps retracted.
> > > Is this normal, and if not, what corrective action need I take?
> > >
> > > Chuck Harrison
> > > Akron, Ohio
> > > 90SP36
> > >
> >
>