# Operating in four wheel drive



## ddossey (May 3, 2010)

I have varied terrain on my property and frequently have to switch to all wheel drive while mowing in order to keep in smooth operation. Generally I switch back to two wheel fairly quickly. Are there guidelines for operating in all wheel drive and is it harmful over an extended period of time? Thanks. :usa:


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## Hoodoo Valley (Nov 14, 2006)

Generally speaking, it's best to only use it when needed, but so long as the wheels can slip a little IE not on concrete or pavement, it won't hurt to do as you are now.


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## MBTRAC (May 28, 2012)

Generally most CUT's&/or tractors under 100HP are FWA :Front Wheel Assist (distinguished usually by smaller front wheels than the rear), rather than true 4WD's/AWD's (where the front/rear wheels are the usually the same size & can take equal loads on the axles/drive train).

A FWA system should be preferable only engaged when all tractor wheels are in a straight line on slippery surfaces (this avoids potential axle/diff "wind up" damage). Or if the front steering axle is not aligned straight, only when absolutely required for as limited time as possible - turning sharply when FWA is enaged on high traction surfaces will ultimately cause damage over time, another thing,if bogged don't allow 1 front wheel to spin in the air & then bounce on the ground as the resultant "chatter" can really stress the driveline (instead, to recover build up a earth/rock "ramp" under this wheel)- happy to provide further details if required. 

In the photo below are two of my tractors - blue is an Iseki TX2160 c.18HP Front Wheel Assist/Rear Diff lock only, red is a Mercedes Trac800 c.80HP 4WD/AWD (though to add to complexity this is also selectable 2WD/4WD, can be driven as a constant 4WD on high traction surfaces due to the selectable Diff locks - None or Front&/or Rear&/or Cross Axle engaged)


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## Country Boy (Mar 18, 2010)

Generally you only want to use the front wheel assist on loose surfaces like dirt, gravel, grass, etc and never on pavement. In a FWA system, the front tires tend to spin about 5% faster than the rear to keep them pulling, and doing that on concrete will damage the drivetrain over time. On concrete, there is no ability for the tires to slip to make up for that 5% extra speed, so it puts an incredible amount of torque on the front drive train. If you are off the pavement, you can generally use the FWA long term if it is needed. At least on farm tractors, I will keep it engaged in the field if I think it will be necessary from time to time such as when chisel plowing or working land in spring. It gets turned off when done with the job and I start heading home.


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## ddossey (May 3, 2010)

Thanks for the help! I did not know the difference between FW Drive and FW Assist and particularly the different "speed" of the front and rear and the do's and don't's. This is all good information and very helpful.
DDos


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