DK40SE Squeal When Moving in Reverse.

[Coyote machine]

Hang in there Coyote Machine.

If you can't wait then here are some details of the fittings. The banjo bolts are M18x1.5 thread. I used M18x1.5 to #10 JIC with #10 JIC fittings on a hose. The hose is rather long though as I use it for testing and did not custom fit it to application. Make some measurements. Remove the banjo bolts and hard line (see attache photo). Head to you local hydraulic shop and get some parts. If you do this please post pics of your bolts and hard line.

I don't plan to keep this setup and will reinstall the hardline with the new banjo bolt. If the pressures are correct and no squeal then I will publish that part number. To piece together a bypass kit will cost you over $100. The bolt is $10 and a simple swap with minimal oil spill.

Thanks for the details, Tom; I can wait, if I have to for the part #'s. I just want to help you help us all verify repeatability of 'killing' the squeal:thumbsup:

In the meantime, I have to go play with my brand new Igland GR-20 log grapple!! And then my new Woods BB72X 72"Brush hog mower...
I can't wait for the destruction to begin...

 

[dfkrug]

I am happy to report after many hours of hard work with the tractor I have not heard a single squeal. I am noticing some very faint chirping and whirring though. The chirps occur while accelerating or traveling uphill mostly going forward. Reverse is scary quiet. I don't recall hearing this before but its hard to say cause I don't recall listening for it. I can also here the gears whirring now and I don't recall that before. Maybe it was masked by other noises because it seems much quieter all around in the cab. This may just be paranoia or over sensitivity after the 7 Month ordeal with the squeal. The sounds are not loud at all actually they are quieter than the power steering and loader circuits. I just hope this is normal and not a sign of damage from the 100 hours of restriction, low flow and cavitation.

Good work, Tom.

If low charge pressure caused the squeal only in reverse, I still have to
wonder why you did not get any squeal in froward.

 

[dennis52]

Really impressed, not only by the engineering skills but the professional way you have presented your findings to the forum.

 

[Coyote machine]

Good work, Tom.

If low charge pressure caused the squeal only in reverse, I still have to
wonder why you did not get any squeal in froward.

FWIW, I get squeal in both directions, including forward.

 

[tnewbern]

I am not so sure its the low charge pressure as much as the restriction. Think of what happens when you force the fluid through a restricted opening. There is excess friction creating heat and sometime aeration. This flow is forced directly into the the pump pistons. Don't forget that forward and reverse are out of phase with each other and see things very differently Hydraulically speaking.

I am not so sure that forward is free from this disturbance. It might not present in the same way or oscillate. A slight difference in fluid dynamics and you go from a squeal to just noise. Take a bottle and disturb the air above the opening. If you get it just right you get a nice tone but if you are even the slightest bit off nothing but a bunch of huffing.

Sorry I have not posted the full details yet. I was debating letting go what I found so far for the very reasons unfolding. I decided to do so because I thought others may have some pressure numbers or able to get them. I was also hoping other would check and see it they had the same hardware from the factor. If others pressures are OK or have different hardware (squeal suffers or not) it would be vital information for formulating a solution. Hang in there everybody we have waited months already whats another week. The parts are on the way and hopefully a real solution.

Tom

 

[dourobob]

Hang in there everybody we have waited months already whats another week. The parts are on the way and hopefully a real solution.

Tom

Tom
I (along with many others here and hopefully the folks at KIOTI) admire your patience and your tenacity (along with your engineer's approach) in getting to the bottom of this aggravation with a solution that is valid, verifiable and repeatable.

Looking forward to what you discover in the next week.

Bob

 

[Kiotikarl]

FWIW, I get squeal in both directions, including forward.

I also get it in both directions, in reverse while snowblowing 15-20 inchs of snow this winter the tractor would also jerk in reverse. I also saw that while it was squealing if i would activate de loader joystick there would be less noise.

 

[dfkrug]

Don't forget that forward and reverse are out of phase with each other and see things very differently Hydraulically speaking.

I don't know what you mean by that. In the two different brands of HSTs that I have rebuilt, the FWD and REV circuits seem to be identical.
The flow direction is simply reversed by tipping the swash plate in the
other direction. I would have opened up a DaeDong HST, but I can't find
any broken tractors of that brand.

It makes sense that others are seeing squealing in both FWD and REV. Note
that the LOADS in FWD may not be the same as in REV.

 

[tnewbern]

I have not rebuilt any of these guys or for that matter any HST's what so ever. I am no expert and only speaking from a practical point of view but here is my reasoning.

The pump always turns in the same direction. The angle of the swash plate controls the direction and volume of flow. This flow is through a block and the 2 paths are not identical. The motor and pump are side by side and offset. The pump ports are oriented horizontal and the motor ports vertical. So the lengths and turns are directions are different and so are the flow dynamics. If the reverse circuit happens to be just the right length (tuned) to the disturbance it will oscillate (squeal). For forward the length is different and the circuit is no longer tuned to the disturbance and the noise is much more subtle as there is no oscillation.

This may not at all be whats happening and this is all theory. I am sure I am over analyzing this but its beyond my control I am obsessive. Even though my squeal is gone I can't sleep until I know why and can prove it. I will rest much easier when Coyote Machine and the rest of us are squeal free.

 

[kattywumpus]

Hang in there Coyote Machine.

If you can't wait then here are some details of the fittings. The banjo bolts are M18x1.5 thread. I used M18x1.5 to #10 JIC with #10 JIC fittings on a hose. The hose is rather long though as I use it for testing and did not custom fit it to application. Make some measurements. Remove the banjo bolts and hard line (see attache photo). Head to you local hydraulic shop and get some parts. If you do this please post pics of your bolts and hard line.

I don't plan to keep this setup and will reinstall the hardline with the new banjo bolt. If the pressures are correct and no squeal then I will publish that part number. To piece together a bypass kit will cost you over $100. The bolt is $10 and a simple swap with minimal oil spill.

Not trying to discourage your troubleshoot, and I appreciate all your work and documenting. Just be aware hardline banjo fitting between the HST filter and HST pre-charge port was completely removed from my tractor. This is the same fitting in your picture. This included the banjo bolts. This was noted in an earlier posts. Kioti engineer install a flexible hydraulic line with two 90s, which you can get for free from Kioti if you call them. Replacing the hardline banjo fitting did help but did not completely resolve the issue. For me the problem is very temperature dependent. During cooler temperature, below 65 no squeal, but above 65 degree it comes back.

Note: during Kioti visit the engineer did mention the possibility of replacing the pre-charge hard line between the cooler and the filter to further boost the pressure to the HST. My understanding from Kioti is the pressure at the HST in-port for my tractor is within specification, but since I don’t have a pressure gauge I can’t verify it. Since the in-port pressure was within specification Kioti didn't feel this pre-charge line needed replacing.