I hope this is the right forum area to be posting, I'm new to all this. I see a lot of useful replies and a wealth of knowledgeable people here that I have a few questions for. A new to me JLG 120HX (1996) boomlift followed me home from an auction recently. It had the swing lock pin installed (as it should for transport) but the pin was VERY tight. So I assumed there may be a swing problem and I was right..... It swings CW but not CCW (from either set of controls). All other functions seem fine and the unit is generally in excellent shape. Thanks to good JLG manuals on the internet I did some basic troubleshooting. I get +12 to terminals 3 or 10 depending on which way I want to rotate and these voltages are getting up to the solenoid bank. So it would appear I have a solenoid issue. Bank 1 is Boom elevate and bank 2 is the swing and they are identical so I unplugged the harness and swapped them temporarily, the problem stayed with the swing motor. I measured the resistance of the solenoids - 3 of them were ~5 ohms and one (the one that didn't work) was ~10 ohms. The part number appears to be 7012728 which retails for amounts between 328 and ~680 $ from various on line US sources. I thought perhaps the coil would be separate (and therefore much cheaper!) from the actual solenoid but it doesn't appear to be. My questions are - can the coil be purchased separately? If not, is the replacement of the complete solenoid a complex task? I will have to check around with the various dealers in the Edmonton Alberta area and see who has it and how much.... not opposed to mail order but this far north, I'd like to get it working fairly soon while we still have nice weather so if I can get one locally that would speed things up, but the price is always a consideration. This unit will not be used commercially, I purchased it to maintain my amateur radio towers and antennas as age and other issues are creeping in and I don't look forward to climbing towers nearly as much as I once thought I did.... Thanks for any insights you may be willing to share to my questions. Don
If swapping the wires from one function to another leaves the actuator still not working in a particulat direction it is pointing out that the problem is downstream from the wiring. This leaves the solenoids, valve or actuator suspect. The solenoid coils can be swapped from side to side as well. Before spending cash on a coil, check to see if the coil is bad by swapping sides to see if the problem follows the coil or stays in the actiator. If after swapping the coils the problem stays in the same direction as before it will be in the valve itself or in the actuator. Swap the hoses on the swing motor to see if the problem follows the hoses or stays with the actuator. If it stays with the actuator, the problem is in the actuator. If the problem follows the hose, the problem is in the valve. If the problem stays with the actuator: The actuator (swing motor) assembly has a counterbalance valve manifold assembly attached to it. Inside this valve assembly is a shuttle valve that provides oil to release a swing parking brake. Please verify the brake is being released when activating swing in both directions. If the problem follows the hoses, then the valve needs a looking at. We can cross that bridge after doing the other tests first. You will
Thanks for the suggestions. I swapped the solenoid assemblies between the boom elevate and the boom rotate functions, on the side easiest to reach. Now it rotates in both directions fine AND the boom goes up and down fine as well. I have been testing it all around the yard at low heights and it hasn't had any issues. I want to thoroughly exercise this - have if fixed the issue or merely delayed it? Both solenoids drew the same current (~2.5 amps) on a bench supply and seemed to have the same force when activated. Both went in and out smoothly, certainly nothing obvious that I could see. The wind is howling today so we'll go work on some other projects closer to the ground. Don
Welcome to HEF ve6jy. :drinkup If everything is now working as it should then I'd tend to leave things alone as it would be hard to determine what the problem is/was since all things work proper. BTW, if you're not familiar with the 120HX, are you aware that there is a procedure to test the boom extension safety lock out system? It's an easy test, only takes a few minutes, and should be done before each work shift before working the machine.
Just a quick followup: I used the lift a fair bit last fall and only once over the winter, but it's working just fine and has never failed to activate any of the hydraulic functions. And yes, I have done the boom extension lock out test several times and that works as expected. I sure appreciate JLG putting all their manuals and wiring diagrams etc freely on the net, it sure is nice - and it influenced my decision as to what brand to go after. I wish I could say the same about my Grove MZ 116, it has some idiosyncrasies in the control wiring and/or responses. I sure haven't been able to scare up anything on the net like a decent wiring diagram for it. Regards, Don