By Other day I set up to make 4 easy picks. Well I put stick all the way out to 9 2. Feet and after being told I only going to a another location I brought boom in to 65 feet. I put my 2 way sling on turned around and the boom violently retracted itself about 15'. I shut it down and called my boss. Never had one do that. So what failed.
Did all the sections retract or just one of them? What is the model 2892?
I think it is only section. it is the 2892
If it was only one section it was likely an extension cable that broke. Have you taken the covers off the bottom section yet?
we pulled the boom completely off the crane. boss took it to friends if his that does that
Does the unit have a lot of history of extending while there is a load on the hook?
not since we owned it. I don't like doing that. I put boom out and leave it
Thats good, I know a few guys that will extend or retract under load, but to me that could cause premature failure of the seals on the cylinder and excess wear to the slides and cables.
I put out enough boom to do the job, and don't touch telescope until I fold up for the day. my boss has no qualms about doing that though. then when I am done for the day I raise boom to 80° before retracting. I think it's easier on wear pads and hydraulic system. however if I am mistaken in doing that feel free to correct my thinking
The extend system on that machine is relieved (or should be) and Manitex literature says you can safely extend and retract within the chart subject to friction. As long as you aren't overloaded, you can try, but friction might make it not work. I tend to leave them in place too, but it won't hurt anything. Yes I know this is an old thread.
Never hurts to ease the load on the parts- booming up makes them retract without jumping too. I'm not real clear if the OP's machine is actually broken but assuming all the cables and sheaves are intact, he has a problem with a holding valve or the cylinder. If he has broken cables, well...