Pokeys air leak

[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"
> > >
> >
>