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© 1996-2006 Harald Pietschmann

Four wheel drive systems "Part Time 4WD"

 

Main mode is 2 wheel drive for everyday pavement use. Usually only rear wheels * are powered. When needed (usually beyond pavement) 4WD can be engaged. 4WD is used part of the time. When 4WD is engaged front wheels are powered as well - if the vehicle has manual hubs on the front wheels, they need to be locked first. There are two different settings for 4WD - "high" and "low"  4WD "high", sometimes called high range, cannot be used on dry pavement with a "part time " system. For extreme situations 4WD "low"is available, it cannot be used on dry pavement either. 4WD "low", also called low range, does not provide more traction, however, it provides two to three times more torque at about half or a third of the speeds in high range.  * In some cases front wheels are powered instead Part Time 4WD requires: a transfer case two drive shafts two axle differentials two powered axles   Part time 4WD has no center differential ! how to properly use part time 4WD  how to shift into 4WD when to engage the hubs Useless on pavement or high traction surfaces full time 4WD - all wheel drive - automatic 4WD - combination systems | 2WD use of traction | 4WD layouts | crawl ratio | 4WD components | do you need 4WD? | Learn from professionals to get the most out of your 4WD: 2005 hands-on 4WD seminars