Downhilll slope problem with an L3200 hydrostatic.

[jgibbens]

I was going down a short hill maybe 30% grade in low gear when my tractor started speeding up with no pedal input. I think it was in 4wd. The fel was on but unloaded. Nothing on the 3pt. The brakes did not help slow me down. I don't think the rear wheels were skidding but it happened very quickly and I didn't think to look for skid marks. When I got near the bottom of the hill, the tractor quickly decelerated to a speed that was right for the amount of pedal input I was giving it. The two dealers in my area aren't giving me any answers. Any ideas what's going on here?

 

[RaydaKub]

My guess is that the 4WD didn't engage, maybe the lever wasn't quite all the way or there could be a mechanical failure that needs to be fixed. I'd go back and look for marks. The description is classic slide-down-the-hill.

Put some weight on the rear end, go back and try it again. First time w/o 4wd. After you've changed your shorts , do it a 2nd time w/ 4wd. There should be a marked difference.

 

[s219]

Sounds like 2wd with brakes locked and sliding.

 

[Mowbizz]

Same thing happened to me in 2wd on my BX25D with a big load of lumber on the FEL...scary! Will always use 4wd when descending hills now, load or no load!

 

[Deano]

Sounds like 2wd with brakes locked and sliding.

I second this!

 

[jgibbens]

Thanks for all the replies. I'll try it again in 2 and in 4 to see if thats all it was. Won't be today but maybe tomorrow.

 

[Grandad4]

Hydrostats use the hydraulic system to transfer power to the drivetrain. Hydraulic fluid for the HST is drawn out of the tractor's fluid reservoir using a sump of some kind. If you are on too steep of an incline, the sump inlet can actually draw air instead of fluid, and the tractor freewheels just as you have described. You have to be on a pretty darn steep grade for that to happen, of course, but it is possible and if your hyd fluid is low, it would obviously happen sooner. Needless to say, it is not a good thing for the tractor to operate it for any length of time like that and it is a real safety issue as well. There was a thread about a fellow who got his new tractor stuck on a very steep trail due to this some years ago.

Having it pop out of gear or not be in 4wd could also cause a runaway, of course, but what you describe with a sudden loss of control, no pedal authority and a recovery as the slope leveled out sure sounds like you found out your maximum grade limit... and are thankfully OK.

 

[k0ua]

The fact that the brakes did not help tells the story.. You slid down the hill. Pressing the brakes will not help at all. You were NOT in 4wd. The fact you had nothing on the 3pt just made it worse. If you had proper 3pt ballast it would not have happened even in 2wd with nothing in the bucket. If you load the bucket with something heavy you reduce the weight on the rear wheels. If you go down a hill with a loaded bucket in 2WD, and you don't have a very heavy ballast on the back you will slide every time in 2wd on a slippery hill.
There is nothing wrong with your tractor. You have just learned a valuable lesson. 4wd no matter what going down steep slippery hills if you wish to retain control.. Once the slippage starts, you cannot regain traction, hitting the brakes is the absolute worse thing you could do. You can drop the bucket to the ground to increase drag and also if you have something on the 3pt (throw out the anchor!) you can lower it to the ground.
As long as you can keep the tractor going in a straight line and there is not a drop off at the end, you can just steer and ride it out like you did.
My very steep gravel covered driveway will cause a runaway every time even with a 750 lb ballast on the 3pt if I have a full load (about 1200 lbs) of gravel in the bucket if I am in 2wd. I MUST be in 4wd to safely go down this hill forwards. Of course If I went down backwards It would be OK in 2wd.

If you have a hill this steep, there is never a reason to not have a significant weight on your 3pt. If you want to repeat your experiment just put a little weight in the bucket, nothing on the 3pt stay in 2wd and go for a ride!

 

[JRL305]

The same thing happened to me with a FEL load of dirt. Our driveway is concrete, steep, and twisty. I didn't have it in 4wd and the rear wheels started to hop as the speed increased. I had to drop the FEL on the concrete to get stopped before I went over the side. I won't do that again. LESSON LEARNED

John
kdfta

 

[Ken45101]

I agree with the 2wd scenario. BTDT, have a broken fence post to show for it!

In a similar vein, I was loading the dump trailer on the driveway, with it hooked to the pickup. Too much weight on the tail of the trailer and it reduced the weight on the truck rear wheels and the truck started to slide! I learned to:
1) park the truck in 4wd,
2) pay more attention in how I load the trailer.