PDA

View Full Version : Bucket Truck Boom



Jman32
02-18-2007, 11:38 PM
Has anyone ever had the boom of their truck leave the cradle while traveling down the road?

jimmyjames
02-19-2007, 12:09 AM
Another crew working for the same contractor I do, had the boom on there digger swing loose. The mechanic said the gears that rotate the boom and also keep it in place, sheared off. Luckly they were on a back road and there was no other traffic. The boom was stowed manualy and had to be strapped down.

Jman32
02-19-2007, 07:09 PM
Unfortunately the boom came out of the cradle on my truck, swung out 90 degrees, and of all things hit a pole. My partner and I know for sure that we properly stored it into the cradle after we finished the job. They are investigating it and say that there is no way that it could have come out and swung around like that. It was very windy that day. If anyone else has heard of this happening, please tell me about it.

old lineman
02-19-2007, 08:40 PM
I am just wondering what those tie down straps and ratchets are for.
I must have missed something. We call them tie down straps for travel.
Just wondering!
The Old Lineman

Jman32
02-19-2007, 10:22 PM
There not on our trucks!

Electriceel
02-20-2007, 12:15 AM
What model and length of boom was this??
When was the last time the boom was inspected mechanically??

Anything is possible, but I have yet to see a boom that did not have some sort of cradle to sit in (and or) a tie down.
You had to have noticed the truck leaning.

Insurance company will have fun with that one.
Good luck.

hotwiretamer
02-20-2007, 01:05 AM
We have a new Bucket sitting on an International Tandem chassis.
It has rubber pads that the axles sit on in the back instead of leafs!
When you head down the hwy and go over a culvert or bad bridge, the truck bounces so bad that all the tools in the bucket end up either in the bottom of the bucket, or worse~ out in the road! We ratchet out boom down tightly, but still launch tools out of it!
Make sure your transportation dept. don't let the vendors sell you on this cheap`ass spec!

loodvig
02-20-2007, 08:01 AM
Did you leave the PTO in gear? I've also seen a boom creep up when the oil gets warmer and expands. But only about an inch. I've never seen a boom cradle without a tie down! The trucks we have, have alarms when the boom is up and the truck is put into gear.

old lineman
02-20-2007, 10:06 AM
We have a new Bucket sitting on an International Tandem chassis.
It has rubber pads that the axles sit on in the back instead of leafs!
When you head down the hwy and go over a culvert or bad bridge, the truck bounces so bad that all the tools in the bucket end up either in the bottom of the bucket, or worse~ out in the road! We ratchet out boom down tightly, but still launch tools out of it!
Make sure your transportation dept. don't let the vendors sell you on this cheap`ass spec!


When this truck was spected out the final decision about the type of suspension that would be one the rear tandem axles was dead wrong.
What the comapny selected was the type of suspension used for tandem axle gravel trucks and the like. In reality there is no suspension, just the rubber pads that prevent any compression.
The end result is that the rear wheels transmit every little bump in the road directly to everything above.
It is absolutely critical that the boom is securely tied down otherwise it will bounce in the cradle and end up destroying the structural integrity of the boom quickly.
This will happen because of the cantilever forces exerted either side of the boom rests. It's like breaking a stick over you knee.
The next thing that will happen is that the bins will start breaking down as the tools bounce up and down while driving down the road pounding the bottoms out of the bins.
This suspension should never have been selected in the first place. It likely was done for economics. Bad choice.
What to do now?
It'll cost you, but the truck can be retrofitted with air suspension. The proper suspension that should have been specified it in the first place.
At this point a choice has to be made. Either leave it alone and destroy the body (likely fiberglass and expensive to repair) and eventually damage the boom or lay the truck up and have it retrofitted. Also expensive.
Consider this cost as the price of education.
Get more knowledgeable people involved when specing out trucks. Suggest that they ask the end users, the linemen.
The Old Lineman

tramp67
02-21-2007, 01:24 AM
Some of the newer bucket trucks have a hydraulically actuated latch on the boom, with no other means of securing the boom. Is that what your truck has? Possibly the boom didn't have enough down pressure applied when it was cradled, or the latch mechanism may have failed. A mechanical boom tie down is definitely a better choice, that way you know for sure that the boom won't drift up.

Craftsman
03-01-2007, 08:08 AM
Another crew working for the same contractor I do, had the boom on there digger swing loose. The mechanic said the gears that rotate the boom and also keep it in place, sheared off. Luckly they were on a back road and there was no other traffic. The boom was stowed manualy and had to be strapped down.

I've had the same very thing happened to a digger derrick, fortunately the sheared off rotation pinnion gear jammed , preventing the boom from rotating,as the operator aware that the pinnion had sheared foolishly drove back to the depot along a very busy main road.

topgroove
03-01-2007, 09:45 AM
years ago we had a bucket that had hotstick tools along side the boom somehow one of the sticks came in contact with the lower boom controlls. as soon as the outriggers were lowered the lower boom started to raise and cracked the bottom of the bucket before anyone could trip the emergancy dump.

Squizzy
03-17-2007, 05:03 AM
My crew was working on a LV corner pole and rental bucket we were using started slewing by itself. The two guys in the bucket frantically used the controls to stop it before they hit the bottom of the bucket while the leading hand raced to get the PTO out. We were in the process of removing some corner taps to separate 3 315kva transformers that were in parralel boom pushed into a house service pulled over a consumer pole and totally destroyed the consumers point of attachment. The 19/12 copper conductors were pushed up within 2 inches of each other on the fly jib if they had of touched it would have been real nasty as it was two of us took off to pull the supply on the transformers. We never used another hire bucket after that another had a similar problem with the same type (can't remember the make).
Also had another bucket that while working elevated it would just "slide" there was no hydraulic power behind it, the lock or whatever just wasn't there the engineers and mechanics thought I was starting trouble as they said"thats imposible it can't do that". I took it out after their inspection and test and it happened again with the same thing from the powers that be. My answer was simple I tagged out the truck and refused to remove the tag. After much testing and examining they did actually locate the imposible fault and fixed it. From memory it was related to when you release the controls and let them flick back into position it leaves just enough preasure in the system to prevent the brake from locking.
We have tie down straps on most buckets to prevent bouncing most cannot slew as the stairs and platform assembly won't permit slewing until you elevate the bucket about 4 feet to clear the saftey rails. On the racheting tie down straps that we use we also have a heavy duty coil spring. This was bought in after a guy some years ago left a strap on and elevated his bucket the strap broke he was shot out of the (didn't have his lanyard clipped on yet) bucket and bounced of the deck of the truck and was killed. The springs are supposed to stop this which is probibly true as i have stretched 3 of these without being flung out.

LINETRASH
03-18-2007, 02:09 AM
What is slewing?

Is it drififting up or down by itself?

I actually have had on more than one occasion the bucket drififting or bleeding down because of a leak...

Is this the gist of the thread?

Hell man, i can quote you numerous occasions where the boom did somthing "unexpected"

After living with this **** and being lucky, I pay attention to my trucks.

I can recall with pleasure/horror the time I had a high ranger that leaked down so fast that I was obliged to keep working it until the GF saw me boom down into potheads and phases and grounded the truck.

Things are different now, thanks to us old dawgs who never gave up.

Swamper, I evoke your spirit to back me up on this!

Squizzy
03-19-2007, 04:26 AM
Sorry Linetrash, slewing is moving the bucket sideways different terminology thats all...

old lineman
03-19-2007, 04:14 PM
Ther are numerous reasons why a boom moves when not asked to.
We call it drifting.
Our hydraulic cylinders have had to be equipped with 'holding valves' ever since 1988.
This device retains the oil within the cylinder should a hydraulic line burst.
The holding valves are supposed to be checked for proper fucnction daily prior to use.
Altec units are equipped with a fuse sytem. It's more compact (probably cheaper) and seems effective.
As the packing within a cylinder wears then you can have drifting without any oil escaping the cylinder. So the holding valve does nothing to prevent it.
That's what happens when you reach your work position and begin to work. After a while you realize that you reaching, because the buckets are descending (drifting). So you reach over and raise the buckets again.
Oil is bypassing the packing and allowing the ram to move. It NEVER gets better by itself.
A tear down is required to rebuild the cylinder. Lots of this type of wear occurs when the filters are neglected or the pump is disindegrating.
If the controls are not self centering there could be wear that allows a minute amount of oil to circulate into/out of the cylinder while the controls appear to be in the neutral position. Thats when you could experience slewing or rotatio or other weird movements.
The control spooles a being left out of their closed position and maintentance is urgent.
You may live with drifting for a while but not slewing or what ever you call it. That's recipie for disaster. It could rotate you right into live conductors before you realize it.
I believe that any unit not performing as the manufacturer intended should be tagged 'out of service' immediately.
The Old lineman