Go Drive & Camp May 2019

10 |May2019go! Drive&Camp

MIC’S MEMOS

R

ecently,Iwas involved

inaconversation

regarding all-wheel

drive(AWD)versus

four-wheel drive(4WD).The

conversation broughthome

some interesting points and

highlightedthe factthatthe

differencebetweenAWDand

4WD is an issue thatelicits many

divergentopinions.

Mainstream 4WDs arevehicles

thatareeither part-time or full-

time 4WD.Anexample ofapart-

time 4WDwould be theHilux

bakkie. Onroad,thedrivemode

is 2WD.Going off-road allows

youtoshiftfrom2H(2WD high

range)to4H (4WD highrange).

When faced with steep climbs

orveryrough,rockyterrain,

youcould shiftto4L(4WD low

range). Shifting from 2Hto4H

or 4L engages the transfer case

attachedtothe gearbox.The

transfer case locks 50% of the

drivetothe frontpropshaftand

50%totherear.

Remember thatwhenavehicle

steers aroundabend,thefour

wheels all turnatdifferent

speeds.The outer frontwheel

turns the fastest and the inner

rear wheel turns the slowest.

While the frontandrear diffsare

open, the diff spider gears can

accommodatethedifference

in speed between the left- and

right-hand side driveshafts.

When the diffsarelocked,

turning becomesveryhard.

Whenyouengage 4H or 4L,

the transfer case essentially acts

likeadifflock andyoucannot

drivethisvehicle onahard

surface. This is duetothe fact

thatwhile turning,thefrontprop

shaftturns slightly faster than the

Thedivision between AWDand 4WD have become

alittle blurred of late,saysMicvan Zyl.

rear and the transfer case cannot

accommodatethisdifferencein

rotational speeds.

FULL-TIME4WDSarealittle

different.Think previous

generationFortuner.Thetransfer

case on thesevehicles can

accommodatethevariation in

speed between the frontandrear

prop shafts when turning while

on tar.Your optionsfor4WD

shifting nowbecome 4H (4WD

high range), 4HL (4WD high

range locked) and 4LL (4WD low

range locked).

When the going getsrough

andyouareno longer on tar,you

can manually lock the transfer

casebymovingto4HL or 4LL.

SO,WHATISthedifference

between 4WD andAWD?

Averysimple waytolookat

it usedtobethefactthata4WD

typicallyallowsyoutomanually

selectthe mode of drivetothe

wheels whereanAWD istypically

avehiclethatautomatesthe

proportioning ofdrivetoany

of thewheels accordingto

circumstances anddemandwith

littleornochoicelefttothedriver.

Essentially,agoodAWD

vehicle puts much of the drive

tothefrontwheels (closestto

the gearbox) ensuring minimal

driveline powerloss. When

thereisaloss of traction, more

powerissenttotherear wheels

tohelp.This can also be split

between the left- andright-hand

wheels.Thesevehiclestypically

haveacentrediff as opposed

toatransfercase.They also

thereforedonot havelowrange

gears or diff locks.You arealmost

entirely lefttothe mercyof the

Micvan Zylist he director of

Ironman 4x4Africa, the sole

importerand distributor of

the fullrangeofI ronman

4x4 products.

ironman4x4.co.za

AWD vs 4WD

programmed electronicstokeep

youonthestraightand narrow.

SomeAWDs mayallowyou

toengagea“4WD”mode which

maytightenthe slip in the front,

rear andcentrediffsbut thatis

not quitethe same as locking

them up thewaya4WD does.

WHILE THISMAYseem

straightforward,theboundaries

between 4WD andAWDhas

becomealittle blurredoflate.

Take theVWAmarok 4Motion

Autoforexample.Unlike the

manual model which has low-

range gears andatransfer

case,theAutohas neither.Itis

aconstant4WD with an eight-

speed automatic gearboxand

someveryfancyelectronicsto

controlitall.

Thefirstcouple of gears are

lowenoughtobesimilarto

someconventional low-range

gearratios onaconventional

4WD with lowrange.The clever

gearboxonly uses these gears

when going off-road.

From whatI’veexperienced,

it is closetoaconventional

transfer case setup andIfor one

would not discounttheAmarok’s

off-road abilitybecause of this.

It is stillaproper4WD.Unlike

typicalAWDs,theAmarok drive

train isrobustenoughtohandle

prolonged 4WD off-road use just

like anyconventional 4WD.