To:               TLCAL@tlca.org
Send reply to:    TLCAL@tlca.org
From:             Karl Klashinsky 
Date sent:        Fri, 30 Aug 1996 17:35:50 -0700
Subject:          Lockers - The Next Generation (from Wall Street Week)

Not sure of the date, but this was kind of interesting.  It gets a
little confusing in the middle, when they switch from axle diffs to
the diffs in full-time 4x4 systems, but just ignore that part 8*)

Also, a footnote... I was at Hollister Hills SVRA on the weekend, and
watched a Grand Cherokee try to climb "5 Fingers Hill".  He got about
5 yards up, and *one* of his wheels started to spin, bringing him to a
complete halt.

I assume the dealer never showed him the "part-time" setting, assuming
the Grand has one... 8*)


In the Lab: Putting the `Four' in Four-Wheel Drive ---- 
By Robert L. Simison Staff Reporter of The Wall Street Journal

  A race is on to fix a shortcoming in some four-wheel-drive
sport-utility vehicles: In slippery circumstances, many of the
off-roaders send power only to the two wheels with the least traction
-- leaving their drivers just as stuck in ice and mud as people with
two-wheel-drive cars.

  This will probably change soon, though, thanks to some inexpensive
new uses of old gearing technologies being developed by Asha Corp. of
Santa Barbara, Calif.; Dana Corp. of Toledo, Ohio; and Britain's GKN
PLC, among others.

  At Dana's outdoor test laboratory, engineers simulate icy patches by
putting rollers under the two left wheels of a top-selling,
state-of-the art, four-wheel-drive sport-utility vehicle perched on a
steep hill climb. The driver steps on the gas; the wheels on the
rollers spin ahead crazily; the wheels on dry pavement do nothing; and
the vehicle rolls slowly backward off the rollers.

  On the same hill, another four-by-four, this one equipped with
Dana's new limited-slip device, takes on the same challenge. This
time, the left-side wheels on the rollers spin a fraction of a turn,
then the two wheels sitting on solid pavement take over, powering the
vehicle off the rollers and up the hill.

  Although most sport-utility vehicles now on the market project a
go-anywhere image, "today, the only vehicle you can buy with true
four-wheel drive is a Hummer [the civilian version of the military's
Humvee personnel carrier], and even it has its limits," says John
Hickey, director of engineering for Dana's Spicer Axle division. A
Ford Motor Co. engineer acknowledges: "What we've been selling is very
obsolete and ineffective."

  The limits of today's vehicles lie in the differential -- the box of
gears that permit the drive wheels to rotate at different speeds when
a vehicle turns a corner or goes around a curve. On most of today's
cars and minivans, the drive wheels are in front; on most pickups, the
drive wheels are in back.  Generally, differentials are engineered to
transfer power to the wheel that is turning faster, leaving the other
wheel to follow along without power. The same principles apply to
four-by-fours, which send power to both front and rear wheels through
a similar device called a transfer case.

  All of this is fine for most driving conditions, and even
necessary. If both or all four-drive wheels are turning at the same
speed, a vehicle will bounce and skip its way through turns, chewing
up tires. In the oldest, simplest four-wheel-drive systems -- dating
back to World War I but still available today -- the driver can lock
all four wheels in gear at the same speed for slippery
conditions. Such systems have to absorb a lot of torque, or turning
force, and thus tend to break down. Another big drawback is that on
dry pavement the driver has to shift out of four-wheel drive.

  Given American drivers' pronounced preference for automatic
transmissions, the idea of shifting into and out of four-wheel drive
won't be acceptable in the U.S., engineers say. "Customers are looking
for passenger-car quality, ride and durability, and they want simpler
controls without a lot of decisions," says John Barlage, a
product-engineering manager for the U.S. automotive operations of GKN.

  GKN and Santa Barbara's Asha have invented competing limited-slip
devices to address this challenge. Like a standard differential, the
new devices permit drive wheels to rotate at different speeds for
cornering. But if too great a difference in rotating speeds develops,
power is transfered from the faster-spinning wheel to its
slower-spinning counterpart.

  Previous limited-slip devices were designed to sense a difference in
torque between drive wheels and then transfer a fraction of the torque
being applied on the slipping wheel to the other wheel. However, in
slick conditions, a slipping wheel may be spinning wildly under almost
no torque, and little or no power would be transferred to the
stationary wheel.

  Dana is preparing to build its Hydra Loc limited-slip differential
for a vehicle maker it won't identify. The Dana product is a version
of Asha's Gerodisc system, developed under license. The Gerodisc uses
hydraulic fluid to transfer power in a slipping-wheel situation. Asha,
an automotive research and development concern, says that it has built
about 25 prototype devices this year for vehicle makers, mostly in the
U.S. and Europe, and that four parts makers have taken out licenses to
build their own versions of the Gerodisc.

  New Venture Gear, a joint venture of Chrysler Corp. and General
Motors Corp., and American Axle Manufacturing Inc., a former unit of
GM, are among those that have licensed the technology.

  Ford says it is working with GKN to develop the British
parts-maker's Visco Lok limited-slip device for installation in future
Ford vehicles. The GKN product uses a different kind of pump than the
Asha product and uses viscous silicon rather than hydraulic fluid to
transfer power from a slipping wheel.

  For consumers, there is one surprising bit of good news: Engineers
in the auto industry say the new limited-slip differentials are likely
to cost $250 to $300 each -- just about the same as today's less
effective devices.

End article

Anyone know if this new "limited slip" is just marketing, or actually
better than current technology?

klash
       |       |       I would have promised those terrorists a trip to
      .|.     .|.      Disneyland if it would have gotten the hostages
     .|||.   .|||.     released.  I thank God they were satisfied with
   .:::::::.:::::::.   the missiles and we didn't have to go to that
                       extreme.
                                     -- Oliver North

To:               TLCAL@tlca.org
Send reply to:    TLCAL@tlca.org
Date sent:        Sat, 31 Aug 1996 15:46:11 +0000
From:             Willem-Jan Markerink 
Subject:          Re: Lockers -- The Next Generation (Wall Street Journal article

On 30 Aug 96 at 17:36, Karl Klashinsky wrote:

> I assume the dealer never showed him the "part-time" setting, assuming
> the Grand has one... 8*)

Never saw a full time 4x4 + T-case without a center lock....
I even dare to say that every US vehicle locks the center diff 
automatically in 4low. Why? Because you would otherwise need a button 
for manual locking on the dash, with the risk of engaging it in 4hi 
on the highway. Even Toyota changed to this on the viscoed/ABS'ed 
80-series after 1992.



> In the Lab: Putting the `Four' in Four-Wheel Drive ---- 
> By Robert L. Simison Staff Reporter of The Wall Street Journal

PS: this is a full copy I assume?
No pictures to please us with?....;-((


>   A race is on to fix a shortcoming in some four-wheel-drive
> sport-utility vehicles: In slippery circumstances, many of the
> off-roaders send power only to the two wheels with the least traction
> -- leaving their drivers just as stuck in ice and mud as people with
> two-wheel-drive cars.


Somehow ignores full time trucks....

>   This will probably change soon, though, thanks to some inexpensive
> new uses of old gearing technologies being developed by Asha Corp. of
> Santa Barbara, Calif.; Dana Corp. of Toledo, Ohio; and Britain's GKN
> PLC, among others.

Mmm....strange....I would have thought GKN (-Viscodrive) headquarters was in 
Germany....even their brochures give reason for this believe.

>   On the same hill, another four-by-four, this one equipped with
> Dana's new limited-slip device, takes on the same challenge. This
> time, the left-side wheels on the rollers spin a fraction of a turn,
> then the two wheels sitting on solid pavement take over, powering the
> vehicle off the rollers and up the hill.

Did they mention the steepness of the hill?

>   Although most sport-utility vehicles now on the market project a
> go-anywhere image, "today, the only vehicle you can buy with true
> four-wheel drive is a Hummer [the civilian version of the military's
> Humvee personnel carrier], and even it has its limits," says John
> Hickey, director of engineering for Dana's Spicer Axle division. A

BS.
They not even restrict this comment to real offroad vehicles .
And with a little arguing, one can even vote against the hummer, 
since it only has a gear driven LSD, not even lockers. There are 
niftier gear trains around in the world....

> Ford Motor Co. engineer acknowledges: "What we've been selling is very
> obsolete and ineffective."

Says more about the brand....8-))


> conditions. Such systems have to absorb a lot of torque, or turning
> force, and thus tend to break down. Another big drawback is that on
> dry pavement the driver has to shift out of four-wheel drive.



And I thought US-consensus was *against* full time trucks....the
only counter arguments of fuel consumption and vibrations seem to
come from across the pond....;-)) 

>   Given American drivers' pronounced preference for automatic
> transmissions, the idea of shifting into and out of four-wheel drive
> won't be acceptable in the U.S., engineers say. "Customers are looking
> for passenger-car quality, ride and durability, and they want simpler
> controls without a lot of decisions," says John Barlage, a
> product-engineering manager for the U.S. automotive operations of GKN.

I feel a new, even less conscious generation of drivers heading at 
us....why did they let the markedroids take over here?....;-((

>   GKN and Santa Barbara's Asha have invented competing limited-slip
> devices to address this challenge. Like a standard differential, the
> new devices permit drive wheels to rotate at different speeds for
> cornering. But if too great a difference in rotating speeds develops,
> power is transfered from the faster-spinning wheel to its
> slower-spinning counterpart.

The tech rep of GKN I spoke with quoted an allowed rotational
difference of 20rpm. This is just a little below idling in a stock
truck in low gear, so even in that case it will work. Not much use
for regeared rock crawlers of course. 
And it indeed engages in fractions of a second, presumably faster
than previous visco units (the rep mentioned that the center diff
unit in VW Syncro's could require several seconds to bind up
completely....but owners say otherwise).
Another typical spec was a maximum torque bias of 3000Nm (2205ft-lbs, 
thanks Mike!....;-)), in case of an airborn-wheel/split-ice 
situation. A few calculations easily show that this is a fraction of 
the power available in 4low....albeit I wonder if any halfshaft can 
take that amount in the first place. Seems to be more or less a 
safety measure, to avoid half shaft breaks by the same consciousless 
drivers. Guess law-a-droids have been involved too....;-((


>   Previous limited-slip devices were designed to sense a difference in
> torque between drive wheels and then transfer a fraction of the torque
> being applied on the slipping wheel to the other wheel. However, in
> slick conditions, a slipping wheel may be spinning wildly under almost
> no torque, and little or no power would be transferred to the
> stationary wheel.

Yep, both geared LSD and friction LSD vary the torque to the slipping 
wheel according to respectively either grip wheel or drive shaft.

>   Dana is preparing to build its Hydra Loc limited-slip differential
> for a vehicle maker it won't identify. The Dana product is a version
> of Asha's Gerodisc system, developed under license. The Gerodisc uses
> hydraulic fluid to transfer power in a slipping-wheel situation. Asha,
> an automotive research and development concern, says that it has built
> about 25 prototype devices this year for vehicle makers, mostly in the
> U.S. and Europe, and that four parts makers have taken out licenses to
> build their own versions of the Gerodisc.

Ah, a new one on the horizon....wonder how fast it can engage....and 
how tight....


>   For consumers, there is one surprising bit of good news: Engineers
> in the auto industry say the new limited-slip differentials are likely
> to cost $250 to $300 each -- just about the same as today's less
> effective devices.

Now we only need them in aftermarket applications....
Oh, and I have been quoted a price of more than $1000 for a 
production run of 1000 pieces....

> End article
> 
> Anyone know if this new "limited slip" is just marketing, or actually
> better than current technology?

As for the ViscoLok:
It is smarter than current friction LSD's, doesn't wear out, and I 
think it is able to put more torque to the grip wheel. 
But still: a geared LSD will prevent slip without inducing it in a 
tight corner, the Visco Lok needs slip to operate, and a friction LSD 
binds in corners under heavy torque.

Anyway, most of the technology is explained in my FAQ on Traction 
Adding Devices:

http://www.a1.nl/phomepag/markerink/mainpage.htm

--
Bye,

       _/      _/       _/_/_/_/_/       _/_/_/_/_/
     _/  _/  _/               _/       _/  _/  _/
     _/  _/ illem    _/     _/ an    _/  _/  _/ arkerink
                     _/_/_/  


The difference 
between men and boys
is the price of their toys


[note: 'a-one' & 'en-el'!]

If you have any question, remark, comment, want to share some philosophy or just want to express your opinion about these pages, feel free to send email to: w.j.markerink @ a1.nl