TEMPS: Downhill in a PT-42 Series 60/Allison

[bumpersbird]

Pete,

On your Allison control pad or I should say I have, D,N,R on one side
on the other side I have one arrow up, one arrow down, and MODE.

Mode is either off or on. It is a preset program designated by the
builder as to how the transmission operates. The mode off is a
factory default setting.

In my case when in MODE ON the coach just runs mostly in 6th at
highway speeds and only down shifts once the engine has allready drop
under something like 1300 RPM. So she's already bogged down. It's
great on the flats.

With MODE OFF she tends to shift a bit too much in cruise. Hit that
overpass and she drops to 5th right now. Keeps the speed set on the
silver leaf exactly, and if it's a long haul uphill the RPM's stay up
and she'll drop to 4th. and just rip up a hill.

I would say in MODE OFF the is tranny working harder, and in MODE ON
the engine is trying to throw power at the tranny. I would like
something in the middle. I guess thats why I started hitting shift
buttons. If I'm cruising down the freeway and in MODE ON and in
cruise, if she doesn't shift befor loosing too many RPM I'll do it
for her.

The arrow keys let you shift gears up or down. Of course you have to
be in the correct RPM range befor she will change gears.

It seems as though my jake is sensitive even a small overpass will
set it off if it's in cruise. The motor spins up just in time for the
jake to cut in.

By the way it will do this going uphill to. Does anyone know why that
happens?

Kurt Horvath
95 PT-42 WLWB
Fayetteville TN




--- In WanderlodgeForum@yahoogroups.com, Pete Masterson
wrote:
>
> In slightly rolling hill country, I use the cruise control and set
> the jake to "low" ... it will keep the coach in a reasonable speed
> band. On more gentle slopes, the jake will slow down the coach by
> about 5 mph before the cruise control kicks in to accelerate.
> Probably uses more fuel in that situation. I generally turn off
the
> cruise control in rolling hills as it's not very good at
maintaining
> an even speed in that situation, since it doesn't anticipate the
next
> up-slope, so I can do better by letting the coach gather a little
> extra speed at the bottom of a hill to let the momentum help with
the
> next upgrade.
>
> Kurt, what is this mode 1 and mode 2 you're talking about? I
hadn't
> heard anything about it. (I'll have to go looking for my Allison
> manual -- I'm pretty sure I have one in the blue box somewhere.)
>
> On my coach, when I'm under jake brake operation the up-shift
doesn't
> occur until 2400 RPM. The engine book explains that "under power"
the
> maximum RPM is 2100 but under no power, the engine is allowed to
go
> to 2400 RPM. (I try to avoid letting it run up above 2100, as much
as
> possible anyway.)
>
> I note that when it's at or above 2100 RPM and I step on the
> throttle, then there's a big delay while the transmission up-
shifts
> before the power comes back on.
>
> As you say, 1800 to 2000 RPM is a pretty good sweet spot for the
jake
> brake.
>
> Pete Masterson
> '95 Blue Bird Wanderlodge WBDA 42
> El Sobrante CA
> aeonix1@...
>
>
>
> On Jun 17, 2008, at 2:35 PM, bumpersbird wrote:
> > <snip> By the way if you run with the cruise on turn off the
> > jake brake. It will activate and fight the cruise control. At
least
> > it does on my coach.
> >
>