Diff Lock / 4wd

[2710Fan]

I know this topic has been touched on before.

I have a new 2710 about 10hrs in the seat, mostly snow pushing but recently mudding around in the garden. Basically, I have left it in 4wd since I got it. I notice that both rear wheels spin when it becomes traction challenged...I've always thought that you had to engage the diff lock to get both rear wheels to turn. (4wd or not) The diff lock pedal is up...at least as high as the reverse hst pedal. I don't think the diff lock is engaged and there is no trouble when turning.

What do you guys think? Anything to worry about here?

 

[RobS]

2710Fan, having both wheels spin without the diff lock engaged may not indicate any problem at all. When one spins and the other doesn't it indicates a significant traction difference between the tires and the diff will favor the tire with less traction. If you are swimming in mud, both tires are likely about the same traction so they'll both spin if able to. You can test by jacking one or both rears up and trying to turn a wheel or just turn a real sharp corner and observe the tires.

You probably don't want to leave it in 4wd all the time, particularly on hard/dry surfaces (or lawn you don't want torn up). The transfer case that controls the 4wd does not have a differential so it will try to turn the front and rear at the same speed. While turning, they need to travel at different speeds and will make up for it by slipping (and tearing up nice lawns).

I just realized I'm describing what I know about my tractor which could be different from yours. If so, someone will chime in and set us straight. Sorry for the long winded explaination, my head cold is affecting my thinking /w3tcompact/icons/smile.gif

 

[Anonymous Poster]

I had the same experience as you; I have a B7500. Just got it this winter and have been using
it for snow in Upstate NY. Had to use the FEL this weekend to build a berm along the driveway
to stop the river of melting snow from washing me out. I was in two wheel drive, had dumped a
load of gravel along the side - the front wheels were over the edge of the driveway (gravel
driveway) - about two inches lower than the driveway itself. As I backed up, the back wheels
both started spinning and dug a nice hole in the driveway. I had to put it in 4 wheel just to back
up (FEL was empty).

Was nice to have the FEL; I originally wasn't going to get it because of the cost and because I
didn't think I'd need it. I moved a nice size pile of gravel a long ways in about an yesterday. If
I had to do it with a wheelbarrow, I'd only be partway through it by now.

I feel guilty though because I don't even work up a sweat! That was the odd thing about the
snowblower too; I was used to using a walk behind and it would get tiring in in heavy snow. With
the B7500 and the front blower, I would just lean on the steering wheel and chug along. Wouldn't
be tired when I was all done; was nice.

 

[Bird]

I think Rob's answer is as good a one as there is. Pretty easy to check it like he said, and I'd get it out of 4WD on solid surfaces.

Bird

 

[Knight9]

Bird,

I've seen others post on the use of 4wd, but it seems to me I remember reading lots of posts where people indicated that they leave it engaged all the time except for mowing. As a relative newbie to tractors, what is the correct approach?? Obviously 4wd will scuff the lawn more when mowing, but is there a mechanical reason or wear reason you don't want to leave the tractor in 4wd for other uses??

Thanks,
Kevin

 

[Bird]

Kevin, I think Rob explained pretty well that the wheels are not always going to be turning at the same speed, and since there's no third differential (one between the front and rear axle) there's going to be some stress there that has to be released somewhere.

Now just how serious it is, I really don't know. In 1995, I looked at a B7100 rental unit the dealer wanted to sell with 800 hours on it, and commented on the fact that it was in 4WD and he said they just left their rental units in 4WD all the time. My B2710 manual tells about shifting from 2WD to 4WD and then the "Important" note says to use the clutch when shifting, and "Tires will wear quickly if front wheel drive is engaged on paved roads."

Logically, if the tires wear more quickly because the wheels are not all turning at the same speed, there has to be additional pressure on the gears. I can't say how much faster those gears will wear because of it, or whether they may break; I just don't know. But I do know that I don't have any reason to find out. I only engage the 4WD when I need it for the additional traction which is probably less than 30% of the time I'm using the tractor.

Bird

 

[GlueGuy]

I'd go along with what Bird said. If you jack up the rear end (in 2wd), you should be able to check out the differential by turning one wheel. The opposite will normally turn the opposite direction.

Likewise, you should keep it in 2wd except when you need 4wd. I think the manual mentions this (mine did for a B7500). I can really cut my driveway up if I make a sharp turn in 4WD, but 2WD is much kinder./w3tcompact/icons/smile.gif Likewise, there is additional wear on the driveline...

The GlueGuy

 

[dieselpwr]

2710Fan

My NH spins both wheels 95% of the time too... for the very reasons mentioned above. You have to have a significant difference from one side to the other to make favor one wheel. One other easy way to compair them is to get one wheel on a less tractionable surface & one on a better surface & try to really dig in with your FEL while pushing in 2WD. Another way is to get on a gravel driveway or part of the lawn you don't care about & turn a circle as tight as you can. Do it without the diff. lock engaged & then with. You should be able to see the wheel to the inside of the turn slip (& leave marks) when it is engaged. If you don't have trouble turning it is not too likely you have a problem. I have forgotten to disengage the diff. lock on tractors before & believe me, if they are in 2WD & you try to turn with them (slippery or not) they remind you real quick that it is still locked... they don't turn too well./w3tcompact/icons/crazy.gif (thankfully my NH automatically disengages when you regain traction/w3tcompact/icons/smile.gif)

Troy

 

[2710Fan]

Duh...Makes sense now. Thanks for all the great advice.

JB

 

[frank_f15]

2710 FAN i have b2400, just got it in feb, have never had to use dif. lock (yet) as far as leaving it in 4wd, i would suggest u only use it when u need it.when moving snow i leave in 4wd. but be sure to follow advise and use clutch before shifting from one to the other. my motto is never use what u don't need to do the job.