Recently took unit to local Bobcat service dealer when the switch on my control panel would not enable me to switch the aux control on. Prior to taking unit in the hydraulic thumb would sporadically close on its own then continue trying to close placing a continuous load on the hydraulic system (seemed like a solenoid/coil or control valve was sticking open). If I toggled the aux switch off/on from the panel the thumb would start functioning properly again, but after a bit of use the situation would repeat. I suspect I have a control valve, solenoid / coil sticking open and concerned this may cause my new $1200 control panel on/off switch to burn out again. Looked at various hydraulic control and electrical diagrams on https://www.bobcatpartsonline.com/ but am not knowledgeable enough to know what parts diagram I need to look at. Not sure even what keyword to search the diagram for (coil, solenoid, ...).
Good day John I tried opening the link it came up with an error, I can understand your concerns and will try to help. Is the installation by Bobcat or a third party? If you can post any photos of the parts involved, we can possibly make a reference diagram easy to follow. Kind regards Uffex
So in looking at the Hydraulic Circuitry (Manifold) (S/N 563011001 - 563014292) on https://www.bobcatpartsonline.com it seems the two coils / valve assemblies nearest the accumulator control the aux function. But which one typically controls the thumbs clamping function assuming my hydraulic lines are correctly connected? I'll probably try cleaning both as i suspect this is a directional system. good video on how to inspect, clean and diagnose a coil / valve assembly on for others that might need to do so.
Hi john Is the C top valve on Utube the same as yours?
Like this illustration
Not exactly. Mine does not have a spring mechanism that returns the directional valve. Other than that the valves are pretty similar. Having watched several videos on how control valves function, I'm betting I have a bad coil, a bad control switch on the control joystick or some sort of electrical short which continuously sends electric to the coil to close the hydraulic thumb. I'm less convinced the valve is sticking open because when I turn the aux function off / on via the panel the issue stops. If that valve were stuck open it would likely stay open even after the electric signal to the coil were shut off. Because the coil operate correctly for awhile I'm guessing the issue is a short or bad control switch on the joystick.
I took both coils off yesterday and there was no visible damage to either of the aux function coils. The stems also looked clean with no visible scarring, although I didn't remove the actual valve assemblies as I didn't have new o-rings which the earlier video recommended replacing should you ever remove one. I'll call my local Bobcat dealer who recently replaced my main control panel to see if they've seen anything similar occur on excavators.
Hi John If you get hold of a multimeter select DC voltage push the pins into the socket of the solenoid plug . switch it on off you should see voltage. If you suspect the coil, switch it with one you know is working. The vast majority of electric circuits will between the coil and switch have a relay (Common good practice) a wiring diagram would help us establish if that holds firm with your machine.The relay protects the switch it could be that it is the relay that is giving the trouble. If you have a diagram post it we can be sure what we are dealing with. Kind regards Uffex
Hi John we have made an easy read of the hydraulic, we have no wiring diagram for your machine if you would like to share we can make that also. Kind regards Uffex
John Miller What was the problem in the end. I am currently working thru the same issue