Do you know the Year when Rover first started using the center
differential in their trucks? Here in the states I know that New
Process was making a full time 4wd transfer case for GM and Dodge trucks
in the early 70s. These trucks are easy to spot and tell apart from
other 4wd trucks of that era by their lack of any front lock out hubs.
But I agree Rover was probably first, I just don't know for sure since
those old Landies very scarce here in Ohio. (I think I've only ever seen
one on the road)
June 1970 saw the introduction of the Range Rover - although it was a very
different vehicle from today. It was designed as a working 4x4 which would
also offer some comfort - in those days Land Rovers etc were pretty basic.
But the Range Rover still had rubber floor covering and plastic seats so
it could be hosed out after a day working on the farm.
The Range Rover kept the same basic body for over 20 years - although the
original was two door only. And the drivetrain up until a couple of years
ago when the old Buick derived V-8 was replaced with a Ford one. The Land
Rover (Defender) can trace its roots back to the '40s, when it was an
interpretation of the WW2 Jeep.
Dave Plowman firstname.lastname@example.org London SW
Yeah, the center diff makes all the "difference" two rovers, which are
both full time 4 wheel drive. Not all wheel. But I can also lock that
center diff and force the 50/50 power split. What is a good breaking
point definition of AWD, vs. 4WD?
no, this is actually not true. Full time four wheel drive does not
neccessarily transfer torque to non-spinning wheels, where as AWD does. AWD
has traditionaly used viscous couplers to accomplish this but electronic
systems are now being used as well. When I posted originally I was looking
for what exactly was used in the E30 IX's, and thanks to all who replied.
Very much appreciated.
Because "full time" is NOT superior for off-road traction. It just
means "always on" so you get to use it in all road conditions. True 4WD
*is* superior in off-road conditions because the transfer case sends
power (equally) to both front and rear axles. So you will get power
from either axle with traction regardless of what the other axle is
doing. However, since the transfer case has no "differential"
mechanism, the front and rear axles can't turn at different speeds,
which means you can't engage it on dry roads if you intend on turning.
Ah.. and there lies the superiority of the Rover, (or at least the
older ones) a center diff that does allow the front and rear axles to
turn at different speeds- or if you are feeling fancy, you can lock the
center diff and force equal power., However, this goes back to the
beginning of the article and the point I was trying to discern...
from John Burns "Find that hard to believe. The system has a chain
driven transfer case
at the back of the gearbox. It's permanent 4wd, nothing fancy. "
and "Full time 4WD = AWD. "
So it would seem to be a concensus that 4wd=awd, yet the awd still does
not have the off road ability of a 4wd, so all Im asking is that the
two terms not be used interchangabley. :)
Sorry, Fred, but you *agree* (with Corey) that a permanent split defines
4WD, yet you say that the 330xi is AWD. To me, those statements are
incompatible. In fact, the 330xi (using ADB) can move when only
one wheel has traction, which is superior to your 4WD explanation.
It's all semantics anyway; what matters is if the system gets you
where you want to go. My 330xi gets me up snowy roads and our
gravel roads quite well. My Toyota T100 4x4 gets me up most forest
roads that need more ground clearance and lower speeds that my 330xi
(AWD) A variation of four-wheel drive (4WD) designed to improve on-road
traction in unfavorable road conditions or for ultra high performance
driving. All-Wheel Drive (AWD) reduces wheel slippage and provides greater
driver control over the vehicle. AWD usually does not require the driver to
actively engage the system and does not have a low range. AWD automatically
splits engine torque between the front and rear wheels as needed. All-Wheel
Drive is generally an on-road system and is not designed for off-road use.
(4WD) A type of drive system in which both front wheels are connected to its
own differential and axles, and both back wheels are connected to its own
differential and axles. Between these two differentials there is a transfer
case which allows you, in the case of part-time four wheel drive, to switch
between two-wheel drive and four-wheel drive. In full-time four-wheel drive
power is sent to both differentials.
full-time four-wheel drive:
A condition where all four wheels are always being driven by the drivetrain.
It may include the option of part-time (that is, shifting into 2WD for dry
pavement) operation, and may or may not have Hi and Lo 4WD speed ranges. The
British term is "permanent four-wheel drive."
real-time four-wheel drive:
An automatic four-wheel drive engagement by means of an electro-hydraulic
clutch or a viscous coupling incorporated in the drivetrain.
Ferguson four-wheel drive:
A transmission system in which power is distributed through a special
viscous coupling differential, 37% to the front wheels and 63% to the rear
Torsen four-wheel drive:
Based on the principle that a worm gear can drive a roller but not vice
versa, the Torsen differential balances different wheel speeds due to
different travel distances, whereas speed differences due to differing
adherence situations are not balanced. A permanently engaged four-wheel
drive incorporating a torsen differential
automatic four-wheel drive:
(A4WD) A driving system that automatically engages 4WD as needed, usually by
monitoring differences in individual wheel speeds and thus sensing when a
tire is slipping.
part-time four-wheel drive:
A manually selectable four-wheel drive
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