Can anyone explain how "on demand 4 wheel drive" works?. I understand that if the switch is in "AWD" AND something senses a rear wheel spin of 1/5 turn or so then the hubs are engaged by some electromechanical device. What causes the hubs to disengage. Does it pop out as soon as the wheels stop spinning? Why isn't it herky jerk. Is there any particular reason not to leave the switch in this position all the time. Why not. I would love a great expanation of how this works. Thanks a lot.

 

This is how we discovered ours works, different from what the manual says.
You turn awd on, the back wheels spin, the fronts lock in and you are in awd. On all 3 of the scramblers that I have been associated with they stayed in awd until you turned the switch off, and sometimes had to back up a little for the awd to disengage.
You could leave the awd switch in all the time if you wanted but it is not necessary unless you are in a situation that you need awd. The quads are more difficult to turn and handle when in awd.

 

When the AWD switch is depressed, the front wheels should disengage when traction is regained in the rear. That's how it's supposed to work, and that is exactcly how mine works.

 

To oversimplify the way the front hubs work, think of them as on a ratchet. When you turn the AWD switch ON, a magnet locks in the ratchet, so that the front wheels can travel faster than the rear (such as turning, or going down a slick hill in low range after the EBS kicks in [img]i/expressions/face-icon-small-smile.gif[/img] ). However, the 'ratchet' doesn't allow the front wheels to turn more than (I think)) 5 or 10% slower than the rear, so as soon as the rear wheels start to spin, the front will grab, often so quick & smooth you won't even feel it. Turning the switch off disengages the magnet, letting the ratchet freewheel. In reverse, you must press the over-ride button to engage the ratchet, something to remember.

It isn't truly a ratchet, it uses a magnetically actuated hilliard, but it does the same thing. There is no 'sensor' to let it know when the rear wheels spin, it just 'grabs' whenever the front wheels aren't turning fast enough in relation to the rear.