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Hydraulic Capacity Alert System HELP!!!!

Brad08

New Member
Joined
Sep 3, 2015
Messages
3
Location
Texas
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!
 

Brad08

New Member
Joined
Sep 3, 2015
Messages
3
Location
Texas
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.
 

Dualie

Senior Member
Joined
Feb 23, 2007
Messages
1,371
Location
Nor Cal
Have you checked the operators manual. Per law there should be one with the crane.
 

lantraxco

Senior Member
Joined
Jan 1, 2009
Messages
7,704
Location
Elsewhen
Yep, should be a pressure switch some place I would think, and as a guess it's plumbed into the boom cylinder circuit?
 

Dualie

Senior Member
Joined
Feb 23, 2007
Messages
1,371
Location
Nor Cal
will it not lift on the winch or boom? Are you sure you don't have the LMI configured wrong and its cutting out?
 

Tradesman

Senior Member
Joined
Apr 23, 2013
Messages
1,075
Location
Ontario
Occupation
Contractor
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.
 

Brad08

New Member
Joined
Sep 3, 2015
Messages
3
Location
Texas
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.
 

ichudov

Senior Member
Joined
Oct 17, 2014
Messages
432
Location
United States
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.
 

Knepptune

Senior Member
Joined
Nov 22, 2012
Messages
757
Location
Indiana
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
 
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