I have a 2008 National Model 900A 26ton boom truck. For some reason, the hydraulic capacity alert light stays on. This crane won't even pick up a 5000lb shipping container when the truck is parked right next to it. I lost a job today because of it, and need to get it fixed as soon as possible. If anyone has any suggestions for me, I'd greatly appreciate the help!
Have you checked the oil level in the tank?
Yes, oil level is good. There's got to be a some sort of switch or sensor that's bad, just can't find any information on the system itself.
Have you checked the operators manual. Per law there should be one with the crane.
Yep, should be a pressure switch some place I would think, and as a guess it's plumbed into the boom cylinder circuit?
will it not lift on the winch or boom? Are you sure you don't have the LMI configured wrong and its cutting out?
When I first got mine the pump was dialled way back to about 1/3 of its proper setting it never really showed up unless I was doing a heavy lift . I don't know if it was intentional or just got out of adjustment, but it was like a different machine after it was turned up.
There is no owners manual. I bought the crane in an auction and am beginning to think this is why they got rid of it. The crane will not boom up, scope out, or winch up. Before I bought it, I made sure everything worked with no leaks, and it did...just not with a load. Dualie, you say the LMI could be configured wrong...any idea where it's located? Tradesman, the pump is putting out 3500 PSI, until it gets a load, then it's locked out and shows no pressure. My older crane never had none of this safety crap on it, and just had to have common sense when to lift and when to not lift. Therefore, all these safety switches, sensors, etc. are new to me.
Brad08, my opinion is that what you are describing is a simple problem. It is not complicated. You can find out why a warning occurs, disable or bypass the circuit that produces the warning, and see (without any serious load) whether the crane is operational with the circuit bypassed. I have no idea about the specific, what sensor is where or what, but I have a lot of such experience. During such troubleshooting, you will acquire invaluable experience and will know much more about your crane.
If it's an 08 it almost has to have an LMI display. If it doesn't have a computer it has to have an overload alert. Usually a computer will cut out boom down, boom out, and cable up. If it lets you boom down with a heavy load I doubt it's computer related. But it almost has to have some kind of computer system if it's an 08. I'd look into that first and find out what kinda computer it has