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PaulW
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Other tracton improvers available are:
* The newest AWD system that has become popular is a system the detects front wheel different slippage (Rt vs left). When this slippage is detected
(using the brake sensor) a clutch is engaged to operate the rear axle. Both front and rear differentials are open. This is a low cost approach for the
kind of increased traction one might need on an icy day to get up a sloping driveway. For sure it is not for an off road situation or for improved
highway handling. This system is a throwback first used by Subaru way back when. They used a lever to engage a spline to connect the front wheel drive
to the rear diff. Talk about low cost!!
* Another AWD in use for Chevy, Ford, and Ram on their pickups is a Borg Warner transfer case which allows 4hi, 4low and 4A. 4A is called AWD and
operates by using brake wheel sensors to control a clutch inside the transfer to allow use on pavement and off road. Most times these trucks come with
an electric locking rear differential which is operated by the driver for low speed traction limited situations. it is non operational and speeds
somewhere above 25mph. Some models use a torsen limited slip front differential which is always active. Yup, it is pricy and usually only offered on
the premium priced trucks and also their large SUVs.
* So far as I know Jeep Wrangler is staying with manually controlled front and rear lockers. And they limit use to 25mph or lower.
* Not mentioned are various AWD cars that use AWD for improved pavement performance, usually cars with excessive horsepower and/or 3 or 4 electric
motors driving the wheels. Way complicated electronic controls required.
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4x4abc
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pretty impressive what the Toyota engineers have put together!
in the video though they had an unfair helper - they un-buried themselves downhill
Harald Pietschmann
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David K
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I think it is the German Bosch system Toyota incorporates into A-TRAC/ MTS/ Crawl?
I am just happy to have it. No replacement for skill and experience, but it is sure neat the way it crawls up and over things with ease!
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4x4abc
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here is the correct use of the terms 4WD, AWD etc:
http://www.rubicon-trail.com/4WD101/4WD-AWD-autoAWD.html
[Edited on 2-9-2019 by 4x4abc]
Harald Pietschmann
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4x4abc
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the hardware for traction control is pretty much the same from all the different vendors
what sets them apart is the software
the engineer in the video points out how early their system reacts to wheel slippage
that is good for slow speed off road stuff
but if your market is mainly fast on road guys, you don't want early intervention
since the vehicle is moving along at a good clip, slippage for a few feet does not hurt anyone
I did a comparison test a few years back and I was the most impressed with what the Range Rover engineers had achieved with their software
looks like Toyota is getting there, too
Harald Pietschmann
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David K
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Roy (The squarecircle) in his Land Rover LR3 showed us how well his vehicle's traction control worked climbing the Widowmaker (on the Mission Santa
María road) in 2007. Three years later, my new Tacoma with its traction control did as well... all my previous 4x4 Tacomas had only the rear locking
differential which was very helpful on such grades.
The Off Road 4x4 Tacoma (since 2009) has three levels of traction control which use spin sensors on each wheel and the ABS braking system as well as
cutting the throttle if over-rev'd. There also still is a locking rear differential for "emergecies" (should A-TRAC not work):
TRAC: Engine regulation (throttle cut) and braking of the slipping tire(s). "Limited Slip Lite"
TRAC OFF: No regulation, just braking of slipping tire(s). "Limited Slip Strong"
A-TRAC/MTS: Matches tire rotation across the axle using brakes. Nearly like front and rear locking differentials but without steering issues. Call it
"automatic lockers" perhaps since it locks the tires together only when needed for traction.
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