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#1
10-19-2016, 01:26 PM
Join Date: Apr 2016
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#2
10-19-2016, 01:43 PM
Polaris ATV Expert
Retired and loving it!
Retired and loving it!
Theoretically around 1/8 turn rear tire slippage for the front wheels to engage is what Polaris has always said but depends on where you're at,what you're doing. Here's an example of how it works in a perfect setting which is on ice.
The electrical part(awd coil) is always armed so to speak when the button is pushed,but the actual mechanical action needed depends on the speed of the prop shaft leading to the front diff,the front diff locking up to power the front drive shafts.Two identical machines in the same condition could vary a little. Same for the old hub activated awd system. Plus if you're a technical kind of guy,here's what the manual shows.. 
"From the service manual....
AWD Engagement: When the AWD switch is activated, the
AWD coil is powered by a 12 Vdc input which creates a
magnetic field. This magnetic field attracts an armature plate
that is keyed to the roll cage. When the ring gear and roll cage
are spinning (vehicle is moving), the energized coil and
armature plate will apply drag to the roll cage that indexes the
rollers inside the ring gear to an engagement position. While in
the engagement position, the front drive will be in an “overrunning”
condition (not engaged), until the rear wheels lose
traction. Once the rear wheels begin to lose traction, the front
drive will engage by coupling the output hubs to the ring gear via
the rollers. The front drive will remain engaged until the torque
requirement goes away (i.e. rear wheels regain traction).
AWD Disengagement: Once the rear wheels regain traction,
the front wheels will return to the “over-running” condition.
The vehicle is now back to rear wheel drive until the next loss
of rear wheel traction occurs
Engagement and diengagement is all mechanical as long as there is voltage to the armature plate...at that point there is no "decision" process.. "sensing" rear wheel slip is completely mechanical. The front and rear gear sets are a different ratio..the front is geared slightly lower..so with no rear slip the front ring gear is turning a little slower than the output hubs/axles..once the rears slip then the front hubs(splined to the axles) slow down but the ring gear doesn't as it is linked by the prop shaft to the rear diff/axles ect...so the when the front ring gear tries to overspeed the front hubs a set of rollers are forced up ramps and lock the hubs to the ring gear...thus driving the front axles..
And once it is locked..it is pretty much a "locker"...each axle is splined to a hub..those hubs get "locked" to the ring gear by the wedged rollers..
no clutch packs per se that you would find in a limited slip.."
"From the service manual....
AWD Engagement: When the AWD switch is activated, the
AWD coil is powered by a 12 Vdc input which creates a
magnetic field. This magnetic field attracts an armature plate
that is keyed to the roll cage. When the ring gear and roll cage
are spinning (vehicle is moving), the energized coil and
armature plate will apply drag to the roll cage that indexes the
rollers inside the ring gear to an engagement position. While in
the engagement position, the front drive will be in an “overrunning”
condition (not engaged), until the rear wheels lose
traction. Once the rear wheels begin to lose traction, the front
drive will engage by coupling the output hubs to the ring gear via
the rollers. The front drive will remain engaged until the torque
requirement goes away (i.e. rear wheels regain traction).
AWD Disengagement: Once the rear wheels regain traction,
the front wheels will return to the “over-running” condition.
The vehicle is now back to rear wheel drive until the next loss
of rear wheel traction occurs
Engagement and diengagement is all mechanical as long as there is voltage to the armature plate...at that point there is no "decision" process.. "sensing" rear wheel slip is completely mechanical. The front and rear gear sets are a different ratio..the front is geared slightly lower..so with no rear slip the front ring gear is turning a little slower than the output hubs/axles..once the rears slip then the front hubs(splined to the axles) slow down but the ring gear doesn't as it is linked by the prop shaft to the rear diff/axles ect...so the when the front ring gear tries to overspeed the front hubs a set of rollers are forced up ramps and lock the hubs to the ring gear...thus driving the front axles..
And once it is locked..it is pretty much a "locker"...each axle is splined to a hub..those hubs get "locked" to the ring gear by the wedged rollers..
no clutch packs per se that you would find in a limited slip.."
#4
10-20-2016, 03:44 PM
