My customer has a M-F tractor with a Nimco 2S40272 Joystick valve. I've rebuilt it twice. Uses it and works fine for 10 minutes or so. Starts to stick then locks up (only the bucket tilt). Lift works fine. It is old (2003) but is in mint condition. Nothing loose or sloppy. I have parts sheet and have been very clean and careful. If anybody knows these valves, I can tell you more by part number. Any help appreciated.
Nimco Valve jamming
- Thread starter redsil
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npalen
Elite Member
Sounds like a heat issue causing the spool to bind. Guess I might consider disassembling then lapping the valve using the spool with a little lapping compound and then a thorough flushing and rinsing prior to reassembly. A couple tenths of a thousandth increase in the bore diameter might fix the problem. The lapping would tend to also correct misalignment due to an ever so slight bend in the spool.
Dave M7040
Elite Member
- Joined
- Dec 10, 2012
- Messages
- 2,757
- Location
- Williamstown Ontario Canada
- Tractor
- Kubota M7040 Nuffield 465
I cannot find that Nimco valve on their web site. Perhaps it is too old.
Typically, spool to valve body tolerances are so fine that normal mechanics do not have the instruments to measure the clearances.
Metrology is the science of making measurements at the level of hydraulic valves.
I would suggest a high quality filter on the suction side of the pump.
Why Hydraulic Spool Valves Stick
The radial clearance between the spool and bore in common, garden-variety directional control valves ranges between 3 and 13 microns. If the clearances between the spool and bore become invaded by hard particles (silt) or soft particles (varnish and sludge), more force is required to move the spool.
Why Hydraulic Spool Valves Stick | Hydraulics & Pneumatics
Dave M7040
Typically, spool to valve body tolerances are so fine that normal mechanics do not have the instruments to measure the clearances.
Metrology is the science of making measurements at the level of hydraulic valves.
I would suggest a high quality filter on the suction side of the pump.
Why Hydraulic Spool Valves Stick
The radial clearance between the spool and bore in common, garden-variety directional control valves ranges between 3 and 13 microns. If the clearances between the spool and bore become invaded by hard particles (silt) or soft particles (varnish and sludge), more force is required to move the spool.
Why Hydraulic Spool Valves Stick | Hydraulics & Pneumatics
Dave M7040
oldnslo
Super Member
Is the mounting surface for this valve flat? It is possible for the mounting bolts to slightly twist a casting causing the spools to bind or stick. Try loosening the mounting bolts to see if the valve frees up. If yes that would point towards the mounting surface not being flat and heat like palen states causing the binding due to different growth rate of materials.
Since this is mechanical operated silting from contamination is less of a concern but still possible.
Since this is mechanical operated silting from contamination is less of a concern but still possible.
I'll check it. Being a rebuilding mech, the customer is the one taking it on/off and bringing it to me. On the bench works just fine, smooth sliding, just after 10 mins or so, stops. I'll try lapping it. I have valve grinding compound. What could possibly go wrong?
npalen
Elite Member
Might try lapping a little then clean, flush, reassemble and put in an oven for a while at about 180 F. Might even want to try the oven thing before lapping to see if the spool sticks.
Cool, I mean, hot idea. I'll try heating it slowly. I guess I'll have to take the seals out first! Thanks, fellas for the ideas.