bx takes off down hill.

[rbarker]

The second you hit your brake ( which is the natural response under the circumstance ) the skids start because gravity will over come your tires tread ability to resist momentum.

You're right if it was a skidding incident. I re-read his post, though and it's hard to tell if that's what happened. My thoughts run more towards the poster who thought the weight came off the back wheels thus making hydro and braking essentially useless. With no counterweight the rear gets light real easy with the loader on and a little weight in the bucket. Could have been a combination of the two. I think 4 wheel drive would have helped a lot in this situation since the front wheels would not have been free wheeling. I try to remember to use 4WD whenever I go up or down a hill of more that about 10 degrees, even when just mowing with no loader or BH. But then, I tend to be overly cautious (read: chicken!)

 

[AceDeuce]

I shook my head when I read this post because it's an all too common mistake. Luckily their were no adverse consequences besides a good pucker-moment.

Rule #1: ALWAYS use 4WD on hills, loaded or not. The brake pedal on a CUT only actuates a transaxle brake. That means only ONE WHEEL is effectively braked. The other will spin free or in reverse. When 4WD is engaged ALL four wheels are connected directly to the drivetrain and therefore cannot freewheel (provided you have adequate traction). I'm 99.9% sure that your rear tires lost traction on the hill. Without enough friction force between the tires and the ground... wheeee!

Rule #2: ALWAYS point the load UPHILL regardless of what direction you are going. In your case that would have meant BACKING down the hill with the FEL pointing uphill. This is for better balance.

Rule #3: ALWAYS carry the load as low as possible. Lower CoG = more stability.

 

[copperhead1967]

ok, after reading the replies to my post I think it is a combination of the things mentioned.

I just took off the BH and installed the 5 ft rake. (less weight)

I had doing some general FEL work and have been trying as of late to keep the tractor in 2wd on the gravel driveway. (Less traction)

I usually keep the FEL low when loaded, which I had at the time. However I did not lower the rake as I usually do to keep the weight low. ( not sure what higher weight in the back does on an incline)

I too usually will feather the hydro back a little to control my speed or to stop the tractor. The brakes really aren't too ergonomic for alot of use other than securing the tractor when getting off of it. Your pretty much stabbing in the dark trying to hit them in a emergency situation.

Lessons learned after 406 hrs on the BX.
Leave it in 4wd 99% of the time.
Remember the BH weighs alot more than anything else your putting in its place.
After a long winter remember all the dumb stuff you did in years past.

 

[Pks]

"The brake pedal on a CUT only actuates a transaxle brake. That means only ONE WHEEL is effectively braked. The other will spin free or in reverse."

With all due respect, I would like to point out the previous statement is an overly broad generalization and is highly inaccurate regarding the Kubota B series Compact Utility Tractors. The B series has two wet disc brakes directly coupled to the power flow in each axle. This arraingement allows for independent braking and instant turning by locking of one wheel while the other turns freely.

 

[JoeL4330]

I've posted on the same problem ...very exciting. The problem, as others have observed, is that you are unweighting the rear tires, which lose traction and thus you lose engine braking. Best remedy (other than always backing down) is to use 4wd in such situations, which gives the front wheels engine braking. Weight on the rear helps, but you can be fooled, as I was, by a finish mower (or other implement with wheels) because when you lower it to the ground, you have lost the counterbalance rear weight. SO, 4wd is mandatory, along with seat belt. Incidentally, I don't think dropping the bucket is such a hot idea in those circumstances--with enough momentum, the bucket digging in might send you a** over teakettle...you are already pivoting the tractor around the front wheels as a fulcrum. I might consider forcing it into 4wd in such a situation, knowing that would be hard on the tractor.

 

[techman]

There is actually a circumstance that the hydro could be the problem. If you were low on hydraulic fluid combined with an angle on the tractor, the low pressure charge pump in the hydro could lose oil. This could cause a loss of what is called charge pressure in the hydro transmission. The pistons in the drive motor would be pushed in as they turn and without charge pressure they will not be pushed back out against the swash plate (part of the hydraulic motor-piston assembly). This condition will literally let the hydro free wheel as you may have experienced. In such a situation, pressing the hydro pedal will bring additional oil into the motor and should arrest the free wheeling.

It is not common, but possible if there is insufficient hydraulic oil to keep the hydro at the low charge pressure state. I would check the hydro level to be sure.

paul

 

[AceDeuce]

"The brake pedal on a CUT only actuates a transaxle brake. That means only ONE WHEEL is effectively braked. The other will spin free or in reverse."

With all due respect, I would like to point out the previous statement is an overly broad generalization and is highly inaccurate regarding the Kubota B series Compact Utility Tractors. The B series has two wet disc brakes directly coupled to the power flow in each axle. This arraingement allows for independent braking and instant turning by locking of one wheel while the other turns freely.

I stand corrected. I was referring specifically to CUTs without directional brakes. However, I feel that my comments regarding the thread originator's specific situation still apply. Even if BOTH rears were braked (as would be the case with a tractor equipped as described above) your stopping ability is limited to the amount of traction available. The only interface a tractor has with the ground are the tires. Without sufficient weight on the rear and no brakes or connection to the drivetrain in the front, there may not be enough traction to resist momentum or the force of gravity.

 

[KubotainNH]

I also posted about this recently in the safety section. It's amazing how easily you get used to 4 wheel braking in 4x4. Only having the rear wheels braking can be an eye opener for sure. It's very easy to lighten up the rear enough for slippage down a hill.

 

[RobJ]

If something like that happens you need to remember to use the FEL or the rear implement as a brake. If you lowered the FEL you would have been ok. No way I want to take a high speed ride on a tractor down a hill!!

 

[copperhead1967]

Well if any GOOD can come out of this at least we are all reminded to be safe on our machines. Hope my little ride helped out a few people from experiencing the same thing.