Hacker News new | past | comments | ask | show | jobs | submit
tufy123 | on: Unlocking any car from X brand in most of the world
^ this. 4wd is used on offroads and locks all wheels together, transfering equal power to all wheels. AWD varies power using different technologies, from a simple Haldex that transfers power back when front wheels slip to complex sensor controlled individual wheels. Some are front-biased (generally but not exclusively cheaper ones), some are rear-biased (mainly in sports cars) and some are true AWD, depending on the needs and expected pricing of the vehicle.
ErroneousBosh | parent
Not quite, no. It only locks all the wheels together if you also have axle lockers.

You might have something like a Series Landrover transfer box where in 4WD mode the front and rear axles are locked together and in 2WD mode only the rear axle is driven.

But does that make a Defender, RRC, or Disco with LT230 transfer box which has a lockable diff AWD or 4WD? The centre diff supplies power to both front and rear all the time, but can be locked in slippy conditions otherwise if one wheel spins *none* of the wheels get drive - the axle and centre diff will both spin.

Then what about the later Borg-Warner transfer box in later Range Rovers, where you still have a centre diff and epicyclic gearbox to set high and low range, but there's no diff lock - there's a massive viscous coupling that turns it into a ridiculously stiff LSD.

loading story #50428188