My skid-steer uses a couple of hydraulic spool lockouts to keep the joystick from being operated without the key being on. One solenoid was in the habit of going out intermittently for some time, leaving me with only a half-operable joystick, before I got into it & discovered it wasn't some loose-connection issue. When I did pull out the offending coil, I had no replacement on hand, so I scrounged a coil off of a shelved electric-hydraulic pump - just a typical 12V accessory-electric-hydraulic pump. It worked fine, and I set about looking for an ebay bargain on two coils, thinking it was probably wise to have a spare on hand for the other one. Those coils came in the mail, but with my temp setup working OK, the priority for swapping the newly-arrived one in for the scrounged one dropped pretty low on my to-do list. Some months later, I started smelling hot insulation, and pretty soon could feel that the other coil was cooking-hot. When it started blowing plastic bubbles out the sides, I decided to move that item up on my to-do list again, and swap both the coils out for the surplus ones I'd ebayed almost a year ago, giving myself a pat on the back for my foresight in getting two of them on hand for this. But MUCH to my dismay, though both solenoids are electrically functional (the coils are continuous and have some electromagnetic pull), neither one has anywhere near the strength to operate the lockouts. I swapped my scrounged one back in, thinking I must have screwed up on my wiring, but again, that one worked fine, making half of the joystick operable, with a distinct 'click' when power was applied. The new ones will not even twitch when energized/free on the stem, while my temp one will scoot itself right into position and make the valve workable. So I'm guessing that, for some reason, not all 12V solenoid coils are created alike, even if they fit extremely-similar hydraulic valves? Anyone have any detailed knowledge of this, eg how to select, without having to ferret out an OE replacement? Are there listings of differing pull-strength ratings? Dave
Of course they are not all alike, and also there is the possibility unless marked with the voltage that the coils you got off Ebay are not in fact 12V. I doubt you will find any such ratings on coils, to my knowledge they're all specifically designed to work with a particular valve model or series.
The first step is always to call the dealer and see what your up against for price before wasting time and money otherwise try googleing any numbers that are on the old coils or the numbers your dealer gives you
If I were in MN, I'd call (or drive to?) the dealer, ASV...in Hawaii, not so much, and of course when something like this comes up, as it always seems to, on a Saturday, there's no calling any dealer... Yes, all coils involved here are labeled 12V, same core size, about the same weight and volume, so I'd expect them to have about the same pull, because there's no "fine control" going on with them. These are binary (on or off) devices, so why some would be markedly weaker than others, but be otherwise physically similar escapes me. I see immense price variation between apparently-identical coils when googling for replacements ($20 to $175), but like I said, my random pirated coil worked fine as a replacement, so overspending for an OE version is clearly an option - and one I want to avoid. --Dave
ok here is my take on this. If you got a 12v system you need a 12vcoil! now that being said I do not know if they are rated for how much force they will produce but if they are that would completely be a function of how big the wire size and the number of turns of wire in the coil. How hard it pulls may be the part of the problem on why a given coil will not work on you solenoid. And of course there is always the possibility that you valve may be binding with junk or wear and a normal coil just wont cut it requiring the replacement of valve and coil! Ok next no all coils are not the same! I think the biggest thing you need to look at from what you are describing on the coil melting is that is the coil a CONTINUOUS DUTY coil or is it an INTERMITTENT DUTY coil. There is a huge difference and a Intermittent duty coil when used in continuous duty will fry just like you describe!
The coils should have an amperage rating along with a voltage rating on the tag on the coil. I believe a used coil would also need to be tested with a meggar for bleed off to ground. The thing I have looked for in the past was the size of the center post on the valve has to be just slightly smaller that the center hole on the coil. I've used a local hydraulic valve supplier to find compatible coils for non OEM valves.
Actually it was the OE coils that gave out, not any of my random replacements. First one went out with an 'open' in the coil almost a year ago. Second one has been 'boiling' plastic out the sides and towards the core, which made it necessary for me to use a gear-puller to get the damned thing out. That said, yes, duty-cycle is surely something to look into, though typically insulation isn't rated less than 105C - well above boiling temperature - so just the fact that it's too hot to touch doesn't mean it's gone bad, either.
Thanks, John. None of my coils (now four different types) have any useful ID information on them other than the very-basic 12V designation, with the OEs having nothing but a date-code on them along with the voltage. Yeah, you'd think there'd be better ID. Some for sale cite their current-draw which should be proportional to their magnetic strength, but that doesn't mean they're rated for continuous-duty, so I'd still be guessing. And yes, all my coils (scavenged and ebay-brides) are core-wise identical, though there seem to be slight variations in the length of the core - which don't affect performance visibly. A washer will fill the gap if needed, but it's not really necessary from what I've seen, because the pull of the coil tends also to pull them ON to the shaft anyway, so there's no slippage to be concerned about. Mine are actually not for valve-operation, per se, but for lockouts that lock the joystick, preventing it from being moved in either direction when power is off. I think they may not move spools at all, just lock them in place when not powered. Since I posted earlier, I found I was in a bind - I really needed to use the loader/forks to get some heavy stuff out of my truck, but didn't have a second coil to use to get it operable again. Then it occurred to me that I could probably pirate still another random coil off of my truck's dump-bed pump (electric-hydraulic) and see if it would work, and presto, it did, though it's a completely different design from either the original coils or the other scavenged one that works. It was a real PITA to have to swap out those coils, since I was one short of being able to operate both dump and loader, and the coils can't come out without first removing hoses, but it was the only way to get the job done. I mention that this 2nd "random coil" worked because it's more anecdotal evidence that many are indeed interchangeable - though duty-cycle is still a question in my mind. I can probably get mfr info on these points come business hours Monday... Not sure I can link to photos hosted by Flickr, but here's my attempt... from left, there's the twin ebay-failures (very weak pull), the middle is the failing OE coil (note bubbling plastic), fourth is a 'Delta Power,' (the latest to be pirated), and the fifth a Hydraforce, which I pirated almost a year ago from a disused pump that needs it back. https://www.flickr.com/gp/99860246@N03/SR1ceo
Well, I take it all back, sort of. The pair of ebay coils really DO work, as it turns out. But only if I install what I'd assumed were optional-accessory stamped-metal shrouds, which for all appearances are just protective covers, made of light-gauge steel, with the convenience, for some installations, of providing a threaded port for a 1/2" EMT fitting to neatly house the 12V feed via electrical conduit. But it occurred to me last night that those shrouds /just might/ also help to contain the mag field and concentrate it within the core. My crackpot theory was proven out, because they're now both reinstalled, with shrouds this time, and they work like charms. https://www.flickr.com/gp/99860246@N03/K13xZ2 I gotta circle back now to my initial assumption likely being correct: all same-voltage coils made for this generic purpose (hydraulic valve control) ARE interchangeable, with the caveat that you've gotta match the core diameter and come close to the same coil-length to suit your application, and of course the OD can't run into any obstructions around the installation. Duty-cycles on all that I've looked up are 100%, so that's not an issue. My three random-scrounged coils are sufficient for me to have confidence to again simply look for the best surplus/NOS bargain again next time, which is likely not going to be from the OE dealer. -Dave
Right on! :drinkup
If you have an ohmmeter you can check the resistance of the coils against the originals. Cat coils are usually around 23 ohms.