Erratic Hydraulics
- Thread starter TRH
- Start date
J_J
Super Star Member
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- Sep 6, 2003
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- 18,928
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- JACKSONVILLE, FL
- Tractor
- Power-Trac 1445, KUBOTA B-9200HST
Ever how fast it is now, the regen is going to shove a lot more fluid in there. A smaller valve may solve your problem. Do you really care about fast dump?
It's not so much about fast dump as it is plain old gravity. When dumping the bucket, as the load comes past the center of gravity, the rod side of the cylinder, which was low pressure return oil, becomes pressurized by the weight of the load. The hydraulic system cannot keep up with this sudden change in "demand" and a vacuum forms in the piston end of the cylinder. The regen function allows the cylinder to refill itself, avoiding the delay experienced when the system has to refill the piston end. Yes, if you take great care and go slow, you will almost never have this problem. You can also throttle the maximum dump speed by installing a restriction orifice in the return line.
Gary Sweat
Platinum Member
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- May 9, 2010
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I like the fast dump but not the possibility that I am creating a vacuum in the cylinder or having to wait for it to catch up. If regen corrects or helps to eliminate that then that is what I am looking for. It might also solve TRH's symptoms. For now I just have to feather the valve and wait for it to finally dump.
I've been watching the pressure gauge and if I dump it fast, the pressure is zero. It stays at zero for a few seconds until the pump catches up. If I feather it, I can keep about 5 lbs on the gauge so I know I am not creating a vacuum. It's either a regen or a larger gpm pump and so far I have not found a way to put a bigger pump on the tractor.
Sorry TRH, I didn't mean to jump in with my problem but I do appreciate the advice from everyone.
I think we're missing the point.
The original post stated there was an issue dumping, stoping, then not able to continue dumping. Similar issue with the loader raise circuit. It's really not a regen issue.
I would be more inclined to think there is a flow or intermittent flow issue.
A 1900 has a steering priority valve on the hydraulic pump. At 1000 rpm and below, almost all hydraulic flow goes to the steering.
The original post stated there was an issue dumping, stoping, then not able to continue dumping. Similar issue with the loader raise circuit. It's really not a regen issue.
I would be more inclined to think there is a flow or intermittent flow issue.
A 1900 has a steering priority valve on the hydraulic pump. At 1000 rpm and below, almost all hydraulic flow goes to the steering.
Gary Sweat
Platinum Member
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- May 9, 2010
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- 519
Wouldn't that only apply if he is turning the wheels while using the loader? I don't fully understand the priority valve but without steering movement how would any oil be flowing to the steering?
Gary Sweat said:
On this setup, the priority valve always sends the first 2-2.5 gpm to the steering gear, regardless of steering or not. The "excess" flow then goes to the main hydraulic system. When the engine idles down, pump flow decreases to the point all flow goes to the steering. This was always a problem with these models, when releasing the throttle pedal while dumping or lifting, usually in a tight spot, or inching up to a truck.
Hooked_on_HP
Veteran Member
Since the backhoe works fine the hyd. system is working properly. I would check the quick disconects for the loader hyd. hoses first. Un hook and inspect and reconnect if they look ok. Check the position of your TPH lever. On my 1900 with the backhoe on the tph lever needs to be all the way down. As others have stated make sure you don't have frozen pins on the bucket.
Bill
Bill
RickB
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- Just a Scag
The OP also mentioned that the original hyd oil was contaminated and the suction screen needed cleaning. It would not be out of the realm of possibility to think that the screen was plugged a second time from garbage not flushed from the transmission and rear axle during the first drain/fill cycle.
AKKAMAAN
Veteran Member
A priority valve "secures" a certain max flow to steering independently if pump is delivering a higher flow. Power steering is supposed to be designed to work normal at lowest possible pump flow (engine at low idling rpm).
So if power steering is designed to work with a "normal" speed at a flow of 4gpm, pump must be able to deliver that flow at idling, 600rpm. This is a safety requirement for power steering on tractors. Accordingly pump flow at 1800rpm will be 12gpm...