What is latest opinion/position on BX series slow braking (is it an issue or not)?

[AxleHub]

You got this wrong in your other rant too. Braking (via the brake pedal) is connected to any axles that are engaged. When in 2WD, that means it acts on the rear axle only. When in 4WD, that means both the front and rear axles are braked. This is a very basic and very important thing to understand with tractors. You should engage 4WD in any situation where braking is critical, such as on wet/loose slopes, especially when carrying weight in the front bucket, since the rear wheels will have less traction and reduced braking authority. There are many situations when the HST's braking action (or lack of) is secondary to the actual foot brakes, so it's important to understand how braking via the brake pedal works on one or both axles. Please get that straight.

S219, you are THE ONLY one who has ever said front wherls and rear wheels are braked in 4wd. Think what you are saying . . The front and rear are driven by the hst. The brakes do not interconnect with the hst. The hst coasts. The brakes are rear wheel. 4wd does dynamic braking. The brake pedal is not attachef to dynamic braking.

This is not just me saying it. I talked to several kubota long time tractor owners and they all said the same.

 

[s219]

S219, you are THE ONLY one who has ever said front wherls and rear wheels are braked in 4wd. Think what you are saying . . The front and rear are driven by the hst. The brakes do not interconnect with the hst. The hst coasts. The brakes are rear wheel. 4wd does dynamic braking. The brake pedal is not attachef to dynamic braking.

This is not just me saying it. I talked to several kubota long time tractor owners and they all said the same.

No, it just means you're clueless about the driveline. Any axles that are engaged will be braked because the shaft connecting axles is solid. Doesn't matter if the HST is providing resistance or the brakes.

I can explain this to you, but can't understand it for you. But you can test this with your own tractor on a slippery hill with a load in the front bucket, or just do a search here and educate yourself. Let me help you out -- here you will find a few dozen experienced operators saying the same thing as me, so you can rest assured I am not the only one:

http://www.tractorbynet.com/forums/owning-operating/269508-front-brakes-tractor-there-any.html

http://www.tractorbynet.com/forums/yanmar/14082-4wd-4-wheel-brakes.html

http://www.tractorbynet.com/forums/owning-operating/226484-does-4-wheel-drive-4-a.html

http://www.tractorbynet.com/forums/owning-operating/314656-kubota-bx-2370-out-control.html

http://www.tractorbynet.com/forums/owning-operating/174494-always-use-4wd-hills.html

http://www.tractorbynet.com/forums/owning-operating/72080-when-use-4wd-2.html

The same mechanical connection which enables dynamic front axle braking (which you seem acquainted with) in 4WD enables regular front axle braking via the brake pedal. Same exact thing whether it's the HST providing resistance or the brake pads. Because the front and rear axles are connected in 4WD, anything that brakes one axle has to brake the other, thereby extending the contact patch to the tires on the other axle. This is tractor 101 -- get your facts straight and stop spreading dangerous information. People should know to shift into 4WD when operating on hills to get more effective braking from the brake pedal.

 

[k0ua]

S219, you are THE ONLY one who has ever said front wherls and rear wheels are braked in 4wd. Think what you are saying . . The front and rear are driven by the hst. The brakes do not interconnect with the hst. The hst coasts. The brakes are rear wheel. 4wd does dynamic braking. The brake pedal is not attachef to dynamic braking.

This is not just me saying it. I talked to several kubota long time tractor owners and they all said the same.

Here is the deal, When 4wd is engaged there is a hard connection thru the driveline from the rear wheels (where there are actually brakes) to the front wheels. When you press the brake pedal, the rear brakes engage, slowing the rear wheels, and the front wheels too. When you let off of the hydrostat ( a properly working one anyway and the rear wheels slow and so do the front wheels. If you don't believe this, just go down a really steep slippery hill with no ballast on the 3pt, and a nice load in the front bucket. Be sure to be in 2wd and have a nice ride! Well, really you had better do it it 4WD because you will a heck of a lot safer. If you don't know what I am talking about,.. you will the first time you go down a hill in 2wd, and your rear tires are locked up and scubbing on the ground or grass, an you are picking up speed..

 

[Johnkn]

For what it's worth, the BX25D I purchased new in December, 2014 stops great when I lift my foot off the pedal. Unlike the Paul Short video (wow, that tractor definately has an issue) stopping mine at speed in reverse is actually harsh and jolting. Stopping in Forward is not harsh, and it stops quickly regardless of range or 2/4 wheel drive. I moved 15 tons of blue stone this week, I would back straight up to the pile in high range, 2900 rpm, full speed. One time I let off the pedal quicky and it jolted me so hard it scared me and had a sensation that the tractor was going to tip over backwards. Good luck..

 

[dodge man]

I own a BX 2350 so my comments might or might not be revelant. I suspect the setup is similar.

First off, mine is the kind that is supposed to stop suddenly and it does but I also had problems with it creeping forward.

This problem is worse when cold. It also worse when just partly pushing the Hst pedal down. If the pedal is floored and let go of suddenly, it stops quickly. It's worse in high range because you are less likely to have the pedal floored, as you feather it mine will often still creep forward.

I've spent quite a bit of time studying the linkage and think the main large return spring isn't stretched very much at light pedal applications, hence poor return.

I disconnected the dampener on mine and that helped, but it's still a problem.

Greasing the linkage doesn't seem to help. I disconnected the linkage from the pedal and it pivots freely, grease or no grease.

I think cutting part of a coil out of the main return spring would cure it. It might also cause problems, such as aggravating the sudden stop, increased pedal effort, and probably other things I've haven't thought about.

Is having the tractor creep forward a safety issue? It seems so to me.

 

[AxleHub]

Here is the deal, When 4wd is engaged there is a hard connection thru the driveline from the rear wheels (where there are actually brakes) to the front wheels. When you press the brake pedal, the rear brakes engage, slowing the rear wheels, and the front wheels too. When you let off of the hydrostat ( a properly working one anyway and the rear wheels slow and so do the front wheels. If you don't believe this, just go down a really steep slippery hill with no ballast on the k0ua3pt, and a nice load in the front bucket. Be sure to be in 2wd and have a nice ride! Well, really you had better do it it 4WD because you will a heck of a lot safer. If you don't know what I am talking about,.. you will the first time you go down a hill in 2wd, and your rear tires are locked up and scubbing on the ground or grass, an you are picking up speed..

Greetings k0ua, I'm quite familiar with the differences going down a slope in 2wd vs 4wd . . In fact I wrote about it twice in earlier posts on this thread (once just a few posts back). So I have some questions for you:

1. You say there is a direct connection between rear and front axles when in 4wd. Is that direct connection hydraulic or mechanical rod ?

2. If a tractor's hst is coasting when not pressured (no dynamic braking) . . Then is there mechanical braking on the front axle ?

3. A. If the answer to question 1. Is mechanical rod and not hydraulic . . How can such widely different tire sizes possibly be rod connected and allow radius turns without damaging any gearing? The answer can't be differential and the answer can't be idler gearing I would assume?

3 B. If the answer to # 1. Is hydraulic but you have no dynamic braking . . Then you'd also have no "mechanical" braking . . correct ???


My point in my questions is simple. Scut brakes are wet disc rear wheel located. If the 4wd creates both a direct connection AND a hydraulic connection then how does a parking brake function when the engine isn't running?

 

[k0ua]

The connection is purely mechanical, it is the drive shaft that goes from the rear to the front differential. If you put the tractor in 2wd you break that mechanical connection. The drive shaft still turns driven now by the front wheels, but either dynamic braking or wet disc braking will not be applied to the front wheels. By the way this has nothing to do with hydrostat either, this is still true for geared machines. The same exact things apply. Dynamic braking is applied thru the drive train and engine compression when you let off of the throttle the tractor slows down and when in 4wd the front tires are helping hold back the tractor. If in 2wd, you only have the rear wheels holding back the tractor, AND if the bucket has a heavy load and the 3pt is empty, look out.
But in 4wd the front wheels/tires will help grip the road. Same thing for applying the wet disc brakes, while they are only on the rear axles, they will apply braking force to the front wheels thru the drive shaft if the 4wd connection is made.

Remember the hydrostat is just a hydraulic pump and a hydraulic motor in front of a standard 2 or 3 speed transmission. From the hydro motor on back they are the same as any other gear tractor. Since the "parking brake" and the service brakes are the same brake, and they have nothing to do with the hydrostat, what difference does the engine running have to do with anything.

 

[s219]

The connection is purely mechanical, it is the drive shaft that goes from the rear to the front differential. If you put the tractor in 2wd you break that mechanical connection. The drive shaft still turns driven now by the front wheels, but either dynamic braking or wet disc braking will not be applied to the front wheels. By the way this has nothing to do with hydrostat either, this is still true for geared machines. The same exact things apply. Dynamic braking is applied thru the drive train and engine compression when you let off of the throttle the tractor slows down and when in 4wd the front tires are helping hold back the tractor. If in 2wd, you only have the rear wheels holding back the tractor, AND if the bucket has a heavy load and the 3pt is empty, look out.
But in 4wd the front wheels/tires will help grip the road. Same thing for applying the wet disc brakes, while they are only on the rear axles, they will apply braking force to the front wheels thru the drive shaft if the 4wd connection is made.

Remember the hydrostat is just a hydraulic pump and a hydraulic motor in front of a standard 2 or 3 speed transmission. From the hydro motor on back they are the same as any other gear tractor. Since the "parking brake" and the service brakes are the same brake, and they have nothing to do with the hydrostat, what difference does the engine running have to do with anything.

This is all 100% right and I couldn't explain it better myself.

The main thing an HST does is put a hydraulic pump/motor between engine and the transmission, controlled by your foot, which gives variable and smooth control over the amount of power/rotation sent to the transmission. Everything else is mechanical and similar to a gear tractor. Brakes are part of the mechanical transmission/axle/differential system and act on whatever wheels/axles are connected to them. On almost every tractor I have driven, engaging the parking brake means pressing the brake pedal down and then locking it in place, so it simply locks the brakes. It's extremely simple.

All of the HST is upstream of the transmission. It has nothing to do with axles or gears or 4WD or brakes, nothing at all. It is simply a hydraulic "coupling" between the engine and transmission. Just a way to hydraulically deliver the engine's power to the transmission that allows variable and smooth control.

 

[dodge man]

If you have your tractor in 4wd, the brakes work on the front tires through the drive train. This is a statement of fact, not really open to debate. If you don't understand why, don't worry about it, you don't need to understand it all to run a tractor.

 

[Grandad4]

3. A. If the answer to question 1. Is mechanical rod and not hydraulic . . How can such widely different tire sizes possibly be rod connected and allow radius turns without damaging any gearing? The answer can't be differential and the answer can't be idler gearing I would assume?

Just to respond to this question in addition to the excellent explanations already provided, there may be additional step-up or reduction gearing in the transmission output going to one of the axles and the ring and pinion gear sets in the front and rear differentials will also be quite different, with the rear set having much more reduction since the larger rear tire does not need to spin as many times as the front does to travel the same distance.

As noted, the 4X4 mechanism is really independent of which type of transmission setup is used, although on SCUT's like a BX or GC, which are nearly all HST, the drivetrain is very small, so the whole transmission, gearbox, 4x4 mechanism and rear differential live in very close quarters underneath the driver's fanny. If there's an illustrated parts manual available for your GC, you should be able to see diagrams of the drivetrain components that will help you visualize what's going on.