Re: Les cars

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: farna@xxxxxxx
" 
" That's probably GM ala Allison, or a GM auto designed for big trucks
" (not sure if GM owned/created Allison at the time). With an auto the
" more speeds the bigger and heavier the thing is. I believe the 1940s
" eight speed was a pair of the old Dual Range Hydramatics back to back
" in a single case, and eventually became the Allison used in big trucks
" today. The Dual Range was a big heavy auto, two of them connected would
" be a monster! 

heavy - yes.  strong?  not necessarily.  remember how much an iron
warner weighs compared to a th400 or tf727, which are both
considerably stronger.

yes, allison was a gm div back then.  the first allison auto i know of
was a -6- spd in the '60s, with microscopic ratio splits.  i've since
learned that the detroit diesel [another gm div back then] it was most
probably teamed with, is very 'peaky' and doesn't have a broad useful
rpm range.

amc link: after ww2 the army saw they needed to standardize their
support vehicle fleet.  part of that was a competitive drive-off to
pick the m35/m44 et al 2.5t truck supplier.  reo won; the contract
passed to studebaker, who sold the contract and truck plant to kaiser
willys when they exited the car business.  kaiser was bought by amc,
who turned the truck operation into amgeneral.  that in turn was sold
- still with military contracts, still in south bend - in the early
'80s when renault came on board, because of restrictions on foreign
ownership of defense suppliers, i don't know to whom.  recently it has
come into gm ownership, at least in controlling part.  they inherited
the humvee along with it and have spun off a couple of trucks based on
their own chassis but styled to look like the 'hummer'.

but - backing up - korea happened and reo couldn't ramp up fast
enough, so gm got contracts to make their design as the m135.  it has
the same 302" six used in gmc pickups [and loved by early rodders]
teamed with the same 4sp hydramatic used in cars.

" I've got a feeling that the six, seven, and eight speed vehicles are
" actually three and four speed transmissions with an OD added. The
" gearing is spaced so that gears can be split with the OD and the
" computer does all the shifting.

that would only be the simplest way to design the tranny.

" I know the GM six speed is the three
" speed plus OD with split shifting. There is usually no need to split
" first gear, which would make a seven speed (four plus split shifted OD,
" no split in first). 

are you referring to the new 6L80?  i don't know the details, but...
some company whose web address i can't recapture has
1. a 6-sp controller for the 4L80e [o/d in every gear], and
2. a wide ratio planetary [3.06:1 1st iirc], making the splits useful.

i'd be worried about blowing the o/d up in 1st-o/d though.  that's 3x
the torque the o/d was intended for.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh@xxxxxxxxxxxxxxxxx                       and think what none thought