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 .