How in samhill do 24 bolts attaching the boom to this truck just shear off? http://kutv.com/topstories/local_story_249144326.html
Thats happend to a couple of ladder trucks in the fire department too. Talk about bad luck
Its easy enough to do if the rotex bearings are gone it puts extra stress on the turn table bolts and something lets go. Same thing happens with log loaders the bolts that hold the house to the undercarriage lets go and the house falls over. The bolts snap off once one starts its like dominos. My brother seen it happen at a log sort guy running a heal boom loader reached over to pick up a log and the house flopped over.
It's too bad the thumbnail won't enlarge on the report, I'd like to see the bolts. Most bolt failures are due to one of two reasons, either the bolt is overloaded or the bolt has come loose. I would think for safety's sake there is enough margin built in to this machine that overloading wasn't the cause. I'd be willing to bet the bolts loosened and broke over time to the point where catastrophic failure resulted.
I assume the bolts on that bucket truck holding the boom on must have been hammering probably loose enough to cause movement and it eventually popped the head off the top of the bolt.
This is why I like rotary actuators better I''m sure the bolts were not kept properly torqued because there was no easy way to access them. Problem with those things is that even though there are a lot of bolts only a couple of them see a mojority of the stress, and eventually break, then they just keep popping all the way around. This is why people should build equipment with rotary actuators.
I always wondered why these types of fasteners were not dye indicator types...the so called bleeding bolts. I know they are common in the aircraft industry.
That's an interesting idea. Never heard of bleeding bolts. Do they just change color or what? May not be able to see them with the way some of these bull gear things are set up.
I've never heards of these bolts, but have heard of squirt washers. Basicaly they have a preset torque and release paint when you reach the torque. We have to use them on docks or bridges if we use impacts to bolt the girders together. When the job has hundreds of bolts its better than going over them with torque wrenches.
That sounds like something that you would use when fisrt installing bolts if I'm understanding correctly. The problem here is more with maintaining them than initially torquing them.
I agree, I wasn't suggesting using them for this application. I wouldn't trust them to be the correct torque anyway. I was just thinking out loud if bleeding bolts were like the washers. I googled it and it never really came up with nothing. A couple dealers that sell them and a photo of one but no explanation how they work. As far as the washers go, sometimes the plans say to tighten until 3 nubs release, sometimes 4. This is done with a 1 1/2" drive impact wrench. Not something I would tighten a circle on a crane or excavator with. I've been a crane operator for 20 years and I've never seen a circle come loose after they have been torqued though.