DK45 HST blues

[dfkrug]

Yeah, let's hope it is the servo piston burr that you found. The DK45SE and CT445 are great tractors.

As for testing the servo circuit pressure, you are right that a measurement may not yield enough data to know what is going on. And where is the servo pump located?

I have owned both Kiotis and the equivalent Bobcat, purchased new. I never did get my hands on a Bobcat service manual (paper or PDF CT230) cuz I did not want to pay the big price. The google drive PDF you linked does not work, BTW. Mostly, I want the manuals for hydraulics and electrical schematics. The Kioti manuals I have sure could use some improvement.

 

[Harry in Ky]

I see the link has vanished. Expired at least. I thought I had it downloaded for future reference but that's not working either. Unfortunately my computer skills are still at third grade level. I really don't know what I'm doing much of the time.

The link came from member ptsg back when I was venting frustration on the Bobcat tractor forum some weeks back. I had it open for some time, reading up on different parts when I had time. You might send him a PM, maybe he will send you the file he put up. If so maybe you can do a better job of saving it for future reference than I did.

 

[Harry in Ky]

Yeah, let's hope it is the servo piston burr that you found. The DK45SE and CT445 are great tractors.

As for testing the servo circuit pressure, you are right that a measurement may not yield enough data to know what is going on. And where is the servo pump located?

I have owned both Kiotis and the equivalent Bobcat, purchased new. I never did get my hands on a Bobcat service manual (paper or PDF CT230) cuz I did not want to pay the big price. The google drive PDF you linked does not work, BTW. Mostly, I want the manuals for hydraulics and electrical schematics. The Kioti manuals I have sure could use some improvement.

There is no servo pump. I believe it works off charge pressure, which is steering return flow as I see it. The steering return line leads to a valve body on the right side of the tractor which as I understand it, regulates charge pressure at 250 PSI or so and flow is directed internally to the hydrostat. At least that's what it seemed like to me as I was reading through it. I was mainly looking at/for the servo piston mechanical layout at the time since I was convinced the problem was there, not so much in the hydraulics of it.

 

[tacticalturnip]

@ptsg any chance you still have a link to the manual you provided the OP with previously?

 

[ptsg]

@ptsg any chance you still have a link to the manual you provided the OP with previously?

Sure do. I needed some space on the cloud and ended up pulling a bunch of files out. I'll re-upload this one.

DK35SE_40_45_50.pdf

drive.google.com

 

[tacticalturnip]

Sure do. I needed some space on the cloud and ended up pulling a bunch of files out. I'll re-upload this one.

DK35SE_40_45_50.pdf

drive.google.com

Thank you! Hopefully OP will be waking up to better day now.

 

[dfkrug]

There is no servo pump. I believe it works off charge pressure, which is steering return flow as I see it. The steering return line leads to a valve body on the right side of the tractor which as I understand it, regulates charge pressure at 250 PSI or so and flow is directed internally to the hydrostat.

OK, I see the manual now.

Page 5-7 shows that the 2nd chamber of the dual hyd gear pump supplies flow to a flow divider ("regulate valve" according to Kanzaki/DaeDong), which supplies flow to the PS valve, the PTO control valve, and the 4WD control valve. Charge flow for the HST, including the servo valve comes from the PS valve (as you stated).

When you get this buttoned back up, you may want to assure that all systems that run off the flow divider still work correctly. Since you did find an anomaly on the servo piston, that would seem to be the fault. Possibly quite rare.

I have had the chance to work on a DK35SE that I found for my neighbor 7-8 years ago. A rental unit that was starting to give us problems. Mostly with the safety switches and the PTO control, which used the "regulate valve". Both neighbor and tractor now gone. HST always worked great. Gotta keep that oil clean.

 

[Harry in Ky]

The unit is now back in the case. (which is still on the floor) The few seals we got have been installed, the bulk of the mess has been cleaned up, and I plan to start putting the tractor back together tomorrow. Getting the three pieces back into one doesn't look too bad, but assembling all the rest of the crap around it will be the bigger chore. Lots and lots of overlapping parts, linkages, brackets, etc. Then the sheet metal after that.

The only plus I have is the Bobcat manual being the glorified picture book that it is, there are plenty of photos to study as it goes back together. I doubt that part will go very quickly.

 

[dfkrug]

The only plus I have is the Bobcat manual being the glorified picture book that it is, there are plenty of photos to study as it goes back together.

Well, kudos to you, Harry, for taking on this project. I do think the Bobcat manual is better than the Kioti service manual. I hope the safety switches are not giving you problems.

That DK35SE I referred to was ex-rental, a 2009 model, and had something like 1700 hours on it.

 

[Harry in Ky]

I'm not sure why safety switches would be a problem. They weren't before. That should only affect starting, nothing transmission related.

It's back on four feet again. All the structural bolts are in and hydraulic lines (except the steering valve) hooked back up. I gave up for the day after putting the pedal control linkage back on and concluding I had misplaced the return spring that keeps the controls in neutral when no pedals are being used. I need to find one before the progress will continue.

The real fun begins then. The floor plate, steering column, valve, and all that cowling comes next.

On the plus side. Once the tractor was back in one piece I filled the hydrostat unit right to the top with new oil before I put the overflow pipe back in place. Once filled, it stayed that way, and there are no little puddles of fresh oil under it yet. I take that as good start.