I have a question about the on demand 4WD system, i know the rear wheels have to turn (spin) 1/4 more than the front for the front to kick in, but once the front kicks in, and the rear wheels stop spinning does it go back to 2WD?? If it does, than wouldn't that be a pain in the snow, when the wheels are spinning and then gripping??

Just curious, because I'm seriously thinking of getting a sportsman in the not to distant future.

 

Once the 4 wheel drive is on it is fully locked untill you press the button again.

 

But when you slide the 4WD switch to on it's still in 2WD until the rear wheels spin, so are you saying once the rear wheels spin, then 4WD is locked in until you switch it off??

 

you guys are kidding right?

No - the rear wheels don't spin to engage the front wheels. Try to think of the front hubs as big rachet wrenches. The front axles (inside the hub) turn at the same rate as the rear axles. If the rear wheels slip, the front wheels torque with the front axle. It takes less then 10% of a single rear tire rotation for the front hubs to "ratchet" into locked position (about 7 inches?). This is a considerably better system as the front wheels are free to turn at different rpm for turning etc. and only when needed, engage to the front axle. This is turned off and on using a electro magnet that torques against a armature plate the rotates the roller cage moving 5 rollers inside the hub up the ramps of a device that looks like a large hex nut. When the rollers move from center of the ramps - they contact the outer ring and lock the hubs. You can see parts diagrams at polarisindustries.com - ATV's - Tech center - parts manuals.

 

You cannot tell when the 4WD system engages. It is very smooth and very good.
The system is excellent. The true 4WD capabilities on the Polaris machines are far better than most 4WD systems on the market. Last weekend I easily cruised through a set of ruts with my STOCK Sportsman that a 2002 Honda 450 with 26" vampires and a stock Kawisaki 650 got stuck in. The excellent 4WD system plus the incredible ground clearance makes the Sportsman an INCREDIBLE/AWESOME off road machine.

 

Polaris ATVs have an 18 - 22% difference in ratio between the front and rear tires with the rear tires having a lower ratio. This means that the rear tires must spin 18-22% faster than the front tires for the front hubs to "wedge" and the ATV to become 4WD. If someone was to install larger rear tires this would make the ratio difference greater and therear tire would have to spin even more than 18-22% for the front hubs to engageThe reason for this is so that when the ATV is in 4WD and turning, the inside front wheel is still turning at least the same speed as the rear wheels and the hub will not engage

 

AWD overview
With the AWD activated the bike operates in 2 WD untill rear tires lose traction.
When the rear wheels lose tracion the front wheels rotational speed will decrease,causeing the front drive axle speed to exceed front wheel speed. Restricting the rotation of the drive clutch roller cage,whitch will cause the rollers to climb the ramps of the cam,and become squeezed between the ramps and the ring in the hub
When the hub clutch assembly,wheel hub,and drive axle are engaged, the front wheeles will drive and stay engaged until rear wheel traction is regained ,the front wheele will over ride thehub clutch,pushing the clutch rollers towards the lower part of the cam,disingaging the clutch.

 

Thanks for the reply's!!

My main question was just if the quad stayed engaged in 4WD after the rear wheels regained traction, now i know that it goes back to 2WD, but i also know more about the on demand system know, THANKS!

p.s. WhoDatInDaMud, no i'm not kidding, but thanks anyways.

 

I find the awd on my 99 335 sportsman so subtle that it is hard to tell if it even works. I find in snow it will start to fishtail then the front wheels will kick in and staighten out, but I think they disingage after traction is restored in the rear. I do know I idle through mud holes while the other brands come out spinning.[img]i/expressions/face-icon-small-happy.gif[/img]

 

The front will disengage after they are done providing the added traction. As soon as they are 'unloaded' they will free wheel again. So, 2 wheel drive is just that... front wheels will never spin. With 4x4 switch 'on' it is STILL in 2wd until there is the slightest of rear wheel slip, and then the front wheels lock to the axles... then, when unloaded, you are free wheeling again, or in 2wd until the next time the rear slips.