New problem with broom - lost hydraulics

[dstig1]

So I was using my broom to clear the 4" of snow we got overnight and was going along fine. I get down the drive and back up and at the top use my momentary switch to swing the angle from right to left (it was full right and I wanted to go full left) and it moved left and then stopped dead. This is done with a diverter that pushes on a double acting angle cyl to swing the broom head. Done it plenty of times, but held the switch down longer than normal for the full side to side swing. Now I got nuthin'

Had the wife look at the PTO shaft while I was in the seat (can't leave the seat or kills the tractor) and she says it is spinning plus I can hear it. Gage right after the pump reads dead zero. Not even a blip when you engage the PTO. Broom won't spin and can't angle the cylinder either, not surprisingly with zero pressure. I pulled the whole thing off the tractor but haven't dug into anything yet. I did check fluid in the tank, and it is at normal level. Temp was pretty low on the fluid (as in not overheated but was around 70 F not not cold and thick either). I'm thinking internal pump failure, but this thing has less than 20 hrs on it so far. (Go look up my build thread in Build It yourself if you like.). I think the only next step is to drain some fluid, remove the pump and open it up to see if there is anything in there that blew up. I am puzzled by this as it has been working fine and I wasn't over-speeding it or anything crazy, plus the hydraulics have a pressure bypass valve at 2000 psi, so it should just bypass and not explode if overloaded.

Anything in particular to look for or any ideas what may have caused this? More to come but it may be a bit until I can get it drained and apart.

 

[Doaaj50]

Do you happen to have any pictures of where you were measuring the pressure at?

If a pump is really at 0 psi the shaft would be broken or not spinning for some reason. Typically you would have some flow out of the pump and should build up some pressure. A shaft can break but unless it has some sort of defect, running the pump at relief pressure should not do that type of damage.

Was there any noises that you heard when then system stopped working?

Any diagrams that you could provide would also be helpful. I am not as familiar with Kubota systems.

 

[oldnslo]

If I remember correctly the diverter is tied into the motor circuit. Does the swing cylinder hold position now or can you move the broom by hand? Just wondering if swing cylinder could have failed internally and jamed the diverter now allowing flow through cylinder vs the motor. Long shot but should be simple to check.

Other thing is confirm pump is spinning and that a key or something didn’t fall out so PTO shaft is turning but pump is not.

 

[dstig1]

Do you happen to have any pictures of where you were measuring the pressure at?

If a pump is really at 0 psi the shaft would be broken or not spinning for some reason. Typically you would have some flow out of the pump and should build up some pressure. A shaft can break but unless it has some sort of defect, running the pump at relief pressure should not do that type of damage.

Was there any noises that you heard when then system stopped working?

Any diagrams that you could provide would also be helpful. I am not as familiar with Kubota systems.

If I remember correctly the diverter is tied into the motor circuit. Does the swing cylinder hold position now or can you move the broom by hand? Just wondering if swing cylinder could have failed internally and jamed the diverter now allowing flow through cylinder vs the motor. Long shot but should be simple to check.

Other thing is confirm pump is spinning and that a key or something didn’t fall out so PTO shaft is turning but pump is not.

Yes, this is fully self-contained and does not interact with the tractor hydraulics. The PTO drives the pump on this. The diverter is therefore tied into the motor circuit, as that is all there is for the entire system.

I have not tried swinging it by hand but it did not seem to want to move on it's own while carrying it around on the FEL. The diverter should lock the cylinder fluid passages so I do not expect that it would be movable normally when the diverter is at normal motor position. And the fact that there is zero movement at the pressure gage tells me there is no flow at all. Normally I see near 500-1000 psi when spinning the broom in air. Pressure gage is immediately after the pump (after a 6' hose) right at the pressure relief valve.

I have not yet tried turning the pump by hand but need to. It is a splined shaft and appeared to be intact.

No major noises that would indicate an explosion that I noticed. Probably a clunk or something was all.

Everything was covered in snow and soaking wet, so i was going to wait for it to dry out first and then take a look more closely. Just looking for any thoughts ahead of that on what to look for/consider.

Thanks for the thoughts.

 

[oldnslo]

Dave
Agree on diverter being a slim chance but typically gear pumps don’t just completely fail. I did not follow your build post completely but is there any valves to start and stop or reverse the broom? If yes these could be suspects also.

 

[mrmikey]

Shaft didn't spin on the splines by any chance?

 

[dstig1]

Found the failure point. Pump splined shaft looked ok but a little dinged up plus some smeared metal in the splines. Couldn't turn it by hand (still connected) so I doubt anything internal is bad. Went and stuck a finger in the PTO shaft spline coupler and it was totally smooth, so the coupler spline sheared off. Next question is why?

I put power to the diverter and heard both circuits click with 12 v on each side so I'd guess it is not jammed up.

Need to order some parts now and see what I can do to repair the shaft. But no idea why it failed yet. Maybe my welding annealed it too much or something.

 

[oldnslo]

Interesting failure, if you try to file the PTO internal splines do they seem soft?

Welding could have annealed them.

 

[dstig1]

Looking up the parts I bought to weld up into the shaft coupler, it says "Made from machinable & Weldable Cold Rolled Steel" so that means unhardened mild steel. Methinks that is not strong enough for this application... Not sure where to find anything better so I have a lot of searching to do. This was one of the hardest things to find the first time around, so I may have to replace with the same and just be more careful (and keep a spare on hand)...

 

[oldnslo]

If the pump has a standard spline I believe companies like Dana Spicer, Muncie and others make yokes for them. If you have drive line (shaft) company in your area they could possibly provide one or make a drive shaft for you.