is its possible for a hydraulic valve to stick

[jackww]

hello every one ,i was wondering is possible for a hydraulic valve to stick open ,on the sway control of petti bone lull type forklift? we were recently unloading a bundle of standing seam roof panels and all **** broke loose as they were coming up over the gable end of the building.the driver swears that the controller got stuck causing the lift to roll. how ever the last thing i saw be fore taking cover was this operator looking mighty comfy and relaxed.it appeared he was leaning on the joy stick in a trance and didn't even realize the machine was gonna roll until the ground man started shouting......thanks

 

[kennyd]

Welcome to TBN

Anything is possible.

 

[J_J]

Did you notice if he had a set of earphones on, possibly listening to his Ipod or whatever? Just the weight of your hand and arms could pull or push a lever if you are thinking about other things.

 

[Renze]

yes, floating debris in hydraulic systems can cause valves to stick...

But operators allways blame the machine for their own stupidity.. Just talk to the guys at any warranty department: A guy i knew, checked warranties for VW. He inspected an engine and took oil samples, the engine seized and they wanted a new engine under warranty.

Oil sample proved to be clean, fresh oil !! Conclusion: engine was seized up due to running it without oil. Fresh oil from the jar, couldnt cover this up

 

[Taylortractornut]

They can and do stick, is it a manual valve that connects to the lever or through a linkage. I ran a crane one time that the linkages to the valve banks were a bit worn. They had the clevise type linkages. One of the pins backed out a bit from wear and hung on another pin. It worked like a detent and hung the function causing a minor incident. Trash inside the the valve spool will cause the same thing. Often times the inside liner in the supply hose will get trapped in the spool.

 

[Soundguy]

yep.. anyhing can happen..

think of toyota and gas pedals

soundguy

 

[beenthere]

But I don't thing the toyota was a mechanical linkage problem. They have a computer controlled (by wire) not-talked-about electronics problem maybe.

If there is mechanical linkage on the lift valve, then it may stick...but would remain stuck (IMO).

It might have stuck, but the operator should have then pulled it back. I too think he was making an excuse for being distracted.

 

[Soundguy]

could be a good mix of both.

soundguy

 

[J_J]

I would think that most any kind of debris could jam a spool, and most peope think that a spool will return to neutral automatically. If the pin to the lever should break, after going to detent, could give the same results, run away hydraulics, or until the valve goes into relief. . If you can get to the spool shaft with a tool and pull it back to the neutral, you might save the day. If this a motor spool valve, and it gets jammed, think of what could happen if that controls the wheel motors for the machine.

 

[Mace Canute]

Back when I was a teenager on the farm, I had a hydraulic valve stick on our tractor just from heat. It was a very hot day and I was cultivating, and I was making several very short back and forth swaths in one particular area where I had to lift the cultivator up (then drop it again) several times in succession, only a few seconds between operations. Towards the end of the dinking around, the control lever started to become more and more difficult to move, almost to the point of totally seizing. Once I got out into the open again and the valve had time to cool down somewhat, it was back to normal. Never happened before that and never happened again after. Could it have been debris? Possible, but it didn't seem to fit the cause as well as over heating did.