Hydraulic expertise required!

[DiamondDave]

Hi folks, ive got a critical machine down in my work place and my experience with ut is limited, especually when it comes to hydraulics. Situation isnt helped as there are no schematics.


Basically 2 pistons are used to either push or pull(im not sure which) a bar with wedges attached which in turn interacts with some columns with a tape on the bottoms as the wedged bar moves in or out it raises and lowers the columns.

The problem we are having is the columns are not raising high enough. The pistons move about 1 inch then pressure maxes put and dumps to tank. The bar lowers ok works at about 500psi and when fully home hits 2,500 and i presume dumps to tank, when trying to raise it moves an inch then hits the max pressure and dumps.

Im inclined to think something is jamming in the wedge system as it is hitting this 2,500PSI and dumping however my hydraulics knowledge is limited and i wonder could a valve be stuck or passing? We have hecked solenoids are actuating and hey have been pushed manually. Its just to try and write off hydraulics as the issue.

Cheers qnd apologies for the terrible drawings

https://res.cloudinary.com/engineering-com/image/upload/v1554462332/tips/20190405_111510_llb5ki.jpg

]

 

[LittleInch]

Well it would seem that the hydraulics are ok if indeed 2500 psi is your limit.

If you have no data then it's difficult to know if the unit should be working at 5000 or 10000 psi but instead the relief valve is passing at 2500.

Or it could be that the wedges are jammed.

Your call.


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[btrueblood]

Or maybe somebody kicked the machine up from the 2000 psi design pressure, to, you know, improve things. And then the cylinder shafts got bent by being jammed, and now they don't slide through the bearings as well as they should...

 

[DiamondDave]

Thanks for the replies guys.

Yes place is often a disgrace when it comes to drawings. The gauge only goes up to 3,000 IIRC so id assume its dumping correctly.


Btrueblood- you might be on to something one of the old hands suggested messing about with the relief valve to turn up the pressure...... I didnt because i wasnt happy messing about with something that is set at a limit for a reason and didnt want to damage it.

I wonder if thats already been done....

The wedges seem to come fully retracted as it lowers fully it just wont raise the full height.

 

[gerhardl]

Wondering:

1. Will the hydraulic cylinders work properly, and full length, if the pistons are not connected to any load?

If yes, more pressure and/or less load/mechanical damage on the lifting system.
If no, adjusting (limit switch?) or other internal problem on hydraulic system.

2. Has anything in process or application been changed lately? Irregular tampering or altering (as you indicate) may well be the cause. Note: it is not necessary one single thing causing problems.


3. Oil and system clean?