Hydrostat Whine

[TJP89]

So, my new CK was delivered about a week ago, and I got a brushhog for it last week. This weekend I went through the woods with the set up widening and rerouting trails. As some of you may remember, width was an issue, and I'll say I'm glad I went smaller, as there are still spots I can't get to. Anyway, taking a break from mowing, I used the tractor to take the garbage out (don't laugh, I had a lot of garbage, a really long driveway, I'm lazy, and I'm sure I'm not the only one). On the driveway I put the tractor in High and was surprised by the racket the hydrostat made. I was at about 2300 RPMs with the pedal about 2/3 the way down and the whine was just as loud, at the seat, as the engine. The drive way is flat and there was virtually no load. Now, I know the HST makes this whine, the lawn tractor does it as well, but is this loud normal or is there something going on here? The tractor was well warmed up so oil circulation was not an issue and there were no performance issues at all. So tell me, am I just being paranoid or is there reason for worry?

 

[lockhaven]

I am on a dial up connection so giving the links is not possible for me. Search the forum last year or so there were numerous discussions about the whine in the hydrostatic transmissions. I have a geared so personally cannot help.

 

[whistlepig]

If you can find a hydro static that doesn't whine please tell me who makes it.

 

[k0ua]

They all whine. Some have found that some of the whine is amplified by a resonant condition in the ROPS. The Kubota Bx series are noted for that, and some have shot them full of expanding foam and claims it makes a big difference. The smaller the hydrostat tractor the louder the whine. I don't know why, but this seems to be true. My DK is the largest hydro tractor I have owned ( I have had 3), and it has less whine than the other smaller ones. (one NH, and one Kubota)

 

[KiotiKowboy]

My DK50 HST really has minimal whine. Usually, it's because I've engaged high-range without running up the rpm sufficiently. I rarely get the thing above 2K rpm. Perhaps the cab shields some of the noise? In any event, I hardly notice it.

 

[TJP89]

Yes, I know the hydros whine, I have experience it myself on smaller machines. Just wondering if the whine should be equal to the engine noise. I would guess that it's OK, but not sure. The whine also shows in MED and LOW under heavy load, but not that loud, and the same in HI at slower speed, and I know that's normal, but when I really start to speed up, the noise really gets bad.

 

[Gary Fowler]

They all whine, it is when you don't hear the whine that you should be concerned with, that is just before you need to start walking back home. Yes some whine more than others which I think is resonated noise more than different design of the HST components and yes the whine is more noticeable in higher gears than in lower gears.

 

[SSdoxie]

The whine is result of internal lube oil (case drain) flowing in the HST pump and motor. That flow is proportional to the working pressure in HST and amount of replenishing flow being fed by the charge pump. The higher the working pressure and/or the lower the charge pump flow the louder the whine. Charge pump flow is regulated by the engine RPM, it is fixed displacement pump. Working pressure of HST varies with load on the tractor and what speed range used. High range is almost 4 times faster at full pedal stroke than low range so at same pedal stroke trying to move the same load High range would require HST to work at close to 4X the pressure. My personal feeling is if using High range the engine should be at PTO engine RPM minimum.

 

[Coyote machine]

So, my new CK was delivered about a week ago, and I got a brushhog for it last week. This weekend I went through the woods with the set up widening and rerouting trails. As some of you may remember, width was an issue, and I'll say I'm glad I went smaller, as there are still spots I can't get to. Anyway, taking a break from mowing, I used the tractor to take the garbage out (don't laugh, I had a lot of garbage, a really long driveway, I'm lazy, and I'm sure I'm not the only one). On the driveway I put the tractor in High and was surprised by the racket the hydrostat made. I was at about 2300 RPMs with the pedal about 2/3 the way down and the whine was just as loud, at the seat, as the engine. The drive way is flat and there was virtually no load. Now, I know the HST makes this whine, the lawn tractor does it as well, but is this loud normal or is there something going on here? The tractor was well warmed up so oil circulation was not an issue and there were no performance issues at all. So tell me, am I just being paranoid or is there reason for worry?

High range is really only useable for traveling at a higher speed on a flat road than possible in medium.
Medium is going to be your go to gear for most everything you do. This is IF you have a three speed HST and not a hi/lo two speed....
The DK series 40 HP tractors had a squeal on some, including mine, at 10-12 hours of use. There is a kit that Kioti developed that completely eliminated the squeal on DK-40's. I can't say if it would solve the issue on your model or not.
Thread was something to effect of : DK-40 Squeal in reverse. It goes on for many pages, but does find the problem's solution.
It may or may not peretain to your model's squeal/whine/wine.

 

[HEC]

My cab sure doesn't hide any whine on my B2650 and for some reason it is louder when using cruise control , can't figure that one out . Like others have mentioned the noise must be resonating off something . I don't know why they bother to put a radio in these things as I can't hear mine all that good . I usually wear ear protection when working the tractor at any rate .

 

[ksbrdmkr]

The "whine" has let me know when I have ignored the 4wd light and nor clicked off the 4wd when on the road.

 

[Buggs67]

I've read here where people experience less whine with different UTF. IDK. I'm just about to change my fluids and wouldn't mind less whine.

 

[Coyote machine]

I've read here where people experience less whine with different UTF. IDK. I'm just about to change my fluids and wouldn't mind less whine.

Good luck with fluid change getting rid of the whine. All I know is the DK-40 squeal in reverse instantly goes away, never to return, with the kit that Kioti developed for the issue.:confused3:

 

[k0ua]

Good luck with fluid change getting rid of the whine. All I know is the DK-40 squeal in reverse instantly goes away, never to return, with the kit that Kioti developed for the issue.:confused3:

Yes it does. The kit is nothing more than a T fitting and a 2 foot piece of high pressure hose dead ended. It is a lot like the dead ended pipes that plumbers put on supply lines to stop "water hammer" from happening.

 

[KiotiKowboy]

OK ... I was in the DK50 today, cabbed, for an hour or so and paid special attention to the HST. Unless I lugged the rpms, the HST was almost unnoticeable. Maybe I'm just lucky.

Someone mentioned fluid - I use the TSC Travelers UTF. I felt it was a higher quality than the Xtreme the dealer sold.

 

[k0ua]

OK ... I was in the DK50 today, cabbed, for an hour or so and paid special attention to the HST. Unless I lugged the rpms, the HST was almost unnoticeable. Maybe I'm just lucky.

Someone mentioned fluid - I use the TSC Travelers UTF. I felt it was a higher quality than the Xtreme the dealer sold.

I rarely can hear mine over the engine unless I am really loading it in Med or HI

 

[Coyote machine]

Yes it does. The kit is nothing more than a T fitting and a 2 foot piece of high pressure hose dead ended. It is a lot like the dead ended pipes that plumbers put on supply lines to stop "water hammer" from happening.

It's been a while, but IIRC, the T is a new/different/revised piece from what OE fitting was and it allows flow to the length of hyd hose. Once in place all hydro squeal is gone.

OK ... I was in the DK50 today, cabbed, for an hour or so and paid special attention to the HST. Unless I lugged the rpms, the HST was almost unnoticeable. Maybe I'm just lucky.

Someone mentioned fluid - I use the TSC Travelers UTF. I felt it was a higher quality than the Xtreme the dealer sold.

If you had the squeal in reverse it would be very apparent - there is no mistaking it if it's present. It's NOT about the fluid type used, it IS about the internal valve(s) on some of the DK series, and the retrofit kit is the absolute cure. Can't speak specifically to the CK series - that noise/whine/ issue could be similar cause/effect or not.

 

[k0ua]

The squeal in reverse is nothing like the normal hydro whine.. The squeal in reverse sounded like fingernails on a chalkboard, more or less. It was very rare on my DK35se, I had to run it hard in hot weather for a couple of hours nonstop, then it would start. But I have run it for many hours nonstop in 90 degree heat and the problem is gone after the instal of the kit.

 

[Coyote machine]

The squeal in reverse is nothing like the normal hydro whine.. The squeal in reverse sounded like fingernails on a chalkboard, more or less. It was very rare on my DK35se, I had to run it hard in hot weather for a couple of hours nonstop, then it would start. But I have run it for many hours nonstop in 90 degree heat and the problem is gone after the instal of the kit.

Wasn't saying they were the same noise. What I stated above is that if the squeal in reverse is present on a particular tractor one doesn't have to do anything but drive it and the squeal will show up, especially in reverse. Other whines, from a hydro, are in a different category, they may come and go, and can't be heard at the other end of most neighborhoods, like the reverse squeal can.

 

[coobie]

Good luck with fluid change getting rid of the whine. All I know is the DK-40 squeal in reverse instantly goes away, never to return, with the kit that Kioti developed for the issue.:confused3:

100 percent agree.My Kioti dealer installed the kit CM is speaking of and the whine was totally gone.