Operation in 4 Wheel Drive?

Soundguy · Dec 25, 2004

I would agree.. unliss the jinma have limited slip diffy's.. '4wd' is more like '2wd' . If one front and one rear are off the ground.. tractor won't move. Lock the rear, and one front can still slip.. 3wd..

Soundguy

Brad_Blazer · Dec 26, 2004

It might be a moot point if you have a locking differential but sometimes it helps to apply a little brake to a spinning rear wheel.

bluechip · Dec 26, 2004

Of course this is not a configuration that is unique to Jinma, KAMA or chinest tractors. Most MFWD tractors are like this.
Brad, good point on the brake, that is how many of today computer controlled 4wd systems work, brake the spinning wheel and the remainint one has to turn...

There are a few tractors like the KIOTI DK65 that have front and rear diff locks so you can really dig in with all 4 wheels at once, but it is not normally necessary.

greg_g · Dec 26, 2004

( I would agree.. unliss the jinma have limited slip diffy's.. '4wd' is more like '2wd' . If one front and one rear are off the ground.. tractor won't move. Lock the rear, and one front can still slip.. 3wd..)

Thanks Chris. When put that way, I can now grasp the concept Chip was trying to describe. But I'm curious why - after several hundred hours in 4WD, on three different tractors, in low traction conditions - I've never once observed only ONE front tire turning/spinning.

So I'm going to jump off from where you said "...unliss the jinma have limited slip diffy's...". If the front drive is in fact "open" as Chip describes, why even worry about using 4WD on hard surfaces? Only one front wheel would be driven, the other would just be along for the ride.

It's been my understanding that it is BECAUSE the front drive IS of limited-slip design, that 4WD should be disengaged before driving on hard surfaces. So what am I missing?

//greg//

dieseln · Dec 26, 2004

Sorry - my misconception on a 4wd 'lock' feature on older jimnas... i'll stop using the 4wd on pavement.

bluechip · Dec 26, 2004

The problem from driving in 4wd on hard surface is not in the front or rear diff, but there is NO differential in the transfer case. one front and one rear wheel WILL recieve the power and will be propelled based on the gear ratio regardless of the real rolling ratio of the tires. That can be impacted by inflation, or even the tolerance of the molding process of the tires themselves. No 4wd on hard surface, something has to be able to give and something will, ON pavement it is likely to be something made out of metal that gives, in dirt it is the dirt.

Soundguy · Dec 26, 2004

( that 4WD should be disengaged before driving on hard surfaces. So what am I missing?
)

I also believe the jinma 4wd should be disengaged for hi traction driving. In fact.. just about every 'gear' type fws I've ever seen says to disengage on hi-traction surfaces. I have however seen some FWA systems, or independent hydro drive systems that are ok for hi traction.

It's my guess that while the front wheels can slip side to side.. there is still a possibility of driveline run up from front to rear.. meaning either scuffed tires.. or stressed yokes and shafts.

I obvously don't have one to look at.. or even a manual.. but that would be my 'guess'. so no solid facts here either.

Soundguy

johnk · Dec 26, 2004

Here's a little link on 4 wheel drive that drives to explain things.............

http://www.4x4abc.com/4WD101/def_turn.html

Harrygoodwrench · Dec 26, 2004

Thank you very much John K!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

This thread was going on and on with with useless arguing about 4WD. This is not your AWD car so DON'T use 4WD on hard non slip surfaces, OKAY GUYS,,,,,,,,,,,,,,lets get on with more important things.