Pokeys air leak

[doug_ngl]

OK, As I understand it, The 2 air gauges on the dash only monitor brake
air pressure (not suspension pressure). Under the bus, about in line (F
to R speaking) there are 2 air tanks, one for the front brakes and one
for the rear...I assume. I think there is also a "wet" tank somewhere,
further toward the compressor I would guess. My LH dash gauge bleeds
down many times faster than the RH one (when I shut the rig down). Now
the questions:
Does the LH gauge monitor the air in the LH tank (sounds logical)?
Which tank is for which end brakes? (LH for front? LH for rear?)
Where is the wet tank located?
Thanks as always, still cold here in Gunnison, Doug
Doug Engel, Gunnison, CO, 1981 FC35SB "Pokey"

[Jeff Miller]

The front tank on the driver-side is the front brake tank (also
called secondary), the front tank on the passenger/curb side is
the "wet tank", the tank in the rear is the rear brake tank or
primary.

Pump the brakes very lightly, only the rear gauge should drop.

- Jeff Miller
in Holland, MI


--- In WanderlodgeForum@yahoogroups.com, "doug_ngl"
wrote:
>
> OK, As I understand it, The 2 air gauges on the dash only monitor
brake
> air pressure (not suspension pressure). Under the bus, about in
line (F
> to R speaking) there are 2 air tanks, one for the front brakes and
one
> for the rear...I assume. I think there is also a "wet" tank
somewhere,
> further toward the compressor I would guess. My LH dash gauge
bleeds
> down many times faster than the RH one (when I shut the rig down).
Now
> the questions:
> Does the LH gauge monitor the air in the LH tank (sounds logical)?
> Which tank is for which end brakes? (LH for front? LH for rear?)
> Where is the wet tank located?
> Thanks as always, still cold here in Gunnison, Doug
> Doug Engel, Gunnison, CO, 1981 FC35SB "Pokey"
>

[Doug Engel]

Thanks Jeff. That helps..and limits my crawling around under the bus. Doug

Jeff Miller wrote: The front tank on the
driver-side is the front brake tank (also
called secondary), the front tank on the passenger/curb side is
the "wet tank", the tank in the rear is the rear brake tank or
primary.

Pump the brakes very lightly, only the rear gauge should drop.

- Jeff Miller
in Holland, MI

--- In WanderlodgeForum@yahoogroups.com, "doug_ngl"
wrote:
>
> OK, As I understand it, The 2 air gauges on the dash only monitor
brake
> air pressure (not suspension pressure). Under the bus, about in
line (F
> to R speaking) there are 2 air tanks, one for the front brakes and
one
> for the rear...I assume. I think there is also a "wet" tank
somewhere,
> further toward the compressor I would guess. My LH dash gauge
bleeds
> down many times faster than the RH one (when I shut the rig down).
Now
> the questions:
> Does the LH gauge monitor the air in the LH tank (sounds logical)?
> Which tank is for which end brakes? (LH for front? LH for rear?)
> Where is the wet tank located?
> Thanks as always, still cold here in Gunnison, Doug
> Doug Engel, Gunnison, CO, 1981 FC35SB "Pokey"
>






---------------------------------
Need a quick answer? Get one in minutes from people who know. Ask your question
on Yahoo! Answers.

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

[Gardner Yeaw]

Jeff,
Are you saying that the rear brakes are applied first and not at
the same time as the front brakes?

Gardner
78FC33
--- In WanderlodgeForum@yahoogroups.com, "Jeff Miller"
wrote:
>
> The front tank on the driver-side is the front brake tank (also
> called secondary), the front tank on the passenger/curb side is
> the "wet tank", the tank in the rear is the rear brake tank or
> primary.
>
> Pump the brakes very lightly, only the rear gauge should drop.
>
> - Jeff Miller
> in Holland, MI
>
>
> --- In WanderlodgeForum@yahoogroups.com, "doug_ngl"
> wrote:
> >
> > OK, As I understand it, The 2 air gauges on the dash only
monitor
> brake
> > air pressure (not suspension pressure). Under the bus, about in
> line (F
> > to R speaking) there are 2 air tanks, one for the front brakes
and
> one
> > for the rear...I assume. I think there is also a "wet" tank
> somewhere,
> > further toward the compressor I would guess. My LH dash gauge
> bleeds
> > down many times faster than the RH one (when I shut the rig
down).
> Now
> > the questions:
> > Does the LH gauge monitor the air in the LH tank (sounds
logical)?
> > Which tank is for which end brakes? (LH for front? LH for rear?)
> > Where is the wet tank located?
> > Thanks as always, still cold here in Gunnison, Doug
> > Doug Engel, Gunnison, CO, 1981 FC35SB "Pokey"
> >
>

[Jeff Miller]

It's been a while, I'll dig into the memory banks.

Two things are at work here:

First, the front brakes on FCs and PTs are 20"sq and the rears are
30"sq, so the rear brakes will use air at 150% of the rate of the
fronts (both tanks are the same size) even with the same application
pressure.

Second, the '78 I believe has a valve (can't remember the name of
the valve) which delays front brake application until the main/rear
brakes exceed a set psi (memory tells me it something like 30psi).
Not sure when it changed, but this was to avoid front wheel lockup
in slippery conditions, common on older trucks. In later designs
ratio valves replaced these valves.

- Jeff Miller
in Holland, MI


--- In WanderlodgeForum@yahoogroups.com, "Gardner Yeaw"
wrote:
>
>
> Jeff,
> Are you saying that the rear brakes are applied first and not
at
> the same time as the front brakes?
>
> Gardner
> 78FC33
> --- In WanderlodgeForum@yahoogroups.com, "Jeff Miller"
> wrote:
> >
> > The front tank on the driver-side is the front brake tank (also
> > called secondary), the front tank on the passenger/curb side is
> > the "wet tank", the tank in the rear is the rear brake tank or
> > primary.
> >
> > Pump the brakes very lightly, only the rear gauge should drop.
> >
> > - Jeff Miller
> > in Holland, MI
> >
> >
> > --- In WanderlodgeForum@yahoogroups.com, "doug_ngl"
> > wrote:
> > >
> > > OK, As I understand it, The 2 air gauges on the dash only
> monitor
> > brake
> > > air pressure (not suspension pressure). Under the bus, about
in
> > line (F
> > > to R speaking) there are 2 air tanks, one for the front brakes
> and
> > one
> > > for the rear...I assume. I think there is also a "wet" tank
> > somewhere,
> > > further toward the compressor I would guess. My LH dash gauge
> > bleeds
> > > down many times faster than the RH one (when I shut the rig
> down).
> > Now
> > > the questions:
> > > Does the LH gauge monitor the air in the LH tank (sounds
> logical)?
> > > Which tank is for which end brakes? (LH for front? LH for
rear?)
> > > Where is the wet tank located?
> > > Thanks as always, still cold here in Gunnison, Doug
> > > Doug Engel, Gunnison, CO, 1981 FC35SB "Pokey"
> > >
> >
>

[Gardner Yeaw]

Jeff,
Thank you for the explanation. Now I think understand why I had
problems with the front brakes grabbing when the rear brakes were
way out of adjustment. Since I had the rears set properly the whole
braking experience is significantly better.

Gardner
78FC33


--- In WanderlodgeForum@yahoogroups.com, "Jeff Miller"
wrote:
>
> It's been a while, I'll dig into the memory banks.
>
> Two things are at work here:
>
> First, the front brakes on FCs and PTs are 20"sq and the rears are
> 30"sq, so the rear brakes will use air at 150% of the rate of the
> fronts (both tanks are the same size) even with the same
application
> pressure.
>
> Second, the '78 I believe has a valve (can't remember the name of
> the valve) which delays front brake application until the
main/rear
> brakes exceed a set psi (memory tells me it something like 30psi).
> Not sure when it changed, but this was to avoid front wheel lockup
> in slippery conditions, common on older trucks. In later designs
> ratio valves replaced these valves.
>
> - Jeff Miller
> in Holland, MI
>
>
> --- In WanderlodgeForum@yahoogroups.com, "Gardner Yeaw"
> wrote:
> >
> >
> > Jeff,
> > Are you saying that the rear brakes are applied first and not
> at
> > the same time as the front brakes?
> >
> > Gardner
> > 78FC33
> > --- In WanderlodgeForum@yahoogroups.com, "Jeff Miller"
> > wrote:
> > >
> > > The front tank on the driver-side is the front brake tank
(also
> > > called secondary), the front tank on the passenger/curb side
is
> > > the "wet tank", the tank in the rear is the rear brake tank or
> > > primary.
> > >
> > > Pump the brakes very lightly, only the rear gauge should drop.
> > >
> > > - Jeff Miller
> > > in Holland, MI
> > >
> > >
> > > --- In WanderlodgeForum@yahoogroups.com, "doug_ngl"

> > > wrote:
> > > >
> > > > OK, As I understand it, The 2 air gauges on the dash only
> > monitor
> > > brake
> > > > air pressure (not suspension pressure). Under the bus, about
> in
> > > line (F
> > > > to R speaking) there are 2 air tanks, one for the front
brakes
> > and
> > > one
> > > > for the rear...I assume. I think there is also a "wet" tank
> > > somewhere,
> > > > further toward the compressor I would guess. My LH dash
gauge
> > > bleeds
> > > > down many times faster than the RH one (when I shut the rig
> > down).
> > > Now
> > > > the questions:
> > > > Does the LH gauge monitor the air in the LH tank (sounds
> > logical)?
> > > > Which tank is for which end brakes? (LH for front? LH for
> rear?)
> > > > Where is the wet tank located?
> > > > Thanks as always, still cold here in Gunnison, Doug
> > > > Doug Engel, Gunnison, CO, 1981 FC35SB "Pokey"
> > > >
> > >
> >
>

[Jeff Miller]

Welks.

I believe that it was '82 that BB started installing automatic slack
(brake) adjusters. All prior need regular brake adjusments and
checking, '82-up should just need the adjusters/adjustment checked.

Many of us adjust the brakes tighter before mountain traveling also.

- Jeff Miller
in Holland, MI


--- In WanderlodgeForum@yahoogroups.com, "Gardner Yeaw"
wrote:
>
> Jeff,
> Thank you for the explanation. Now I think understand why I had
> problems with the front brakes grabbing when the rear brakes were
> way out of adjustment. Since I had the rears set properly the
whole
> braking experience is significantly better.
>
> Gardner
> 78FC33