Securement Question

Hydraulics are never allowed to be used to secure a load, because they are prone to leakage or a hose blowing, etc.

However, a crane boom with the hook pulled tight to the machine is Not secured by hydraulics, but by a very reliable winch brake, which is completely mechanical.

I have seen many pictures over the years of excavator booms that bounced at the wrong moment, and ended up taking bridges out.

This is why anything that can move in a way to exceed the Dimensional Limits must be mechanically secured to retain it legal size. And this is based on many instances of problems!

So anything that can swing, lift, extend or otherwise mechanically move, has to be secured.

 

Well a couple of things, first I didn't say hydraulics were allowed to hold down anything, I asked a question, jakehawk9 said the hydraulics keep the boom secure. I even said and you quoted me saying "I've never read anywhere that hydraulics where sufficient to secure the boom".


Second, I've never seen a hydraulic crane with a winch brake they use holding valves not mechanical brakes. Crawlers still have boom dogs but that won't stop a lattice boom from coming up only down. So on a hydro the the only thing holding the boom is hydraulics or your securement.


Third, I would LOVE to see a picture of an excavator boom that "bounced" at the right time and hit a bridge, in calling BS on that one the night have been left up to high but the didn't bounce up. I could see if you were within a few inches of a bridge and the whole trailer bounced you could theoretically hit something.


Fourth, there is nothing nowhere that says "anything that can move in a way to exceed the Dimensional Limits must be mechanically secured to retain it legal size" a machine that's under "legal" size still has to be secured the same as a big one. You are correct when you said "nything that can swing, lift, extend or otherwise mechanically move, has to be secured" its paraphrasing but the essence of the law is there.

 

A lot was already covered, and the legal minimum may be met, but this is basically basing the securement of the entire load on one single point.

In a hard stop, etc, if either of the rear tiedowns had failed, there would be nothing to prevent the load from moving quite a distance, which then gives shock loading on the remaining tiedowns.

At minimum, *I* would have put another chain across the front machine, pulling to the rear, to counteract braking forces (and probably one more across the rear, to encourage the group to stay together lol)

One other glaring issue...
You need to have a chain or strap to prevent the lifts from going up, and exceeding legal height!
The way you had them secured, I would just run one strap or chain over the top of all of them.

When I used to haul for United Rentals, I had a way I normally tied them down, and it left me a loop of slack chain I would put through the corner of the basket, but if I was hauling a bunch, then I would just use another chain and feed it through. No tension needed, just to keep them below 14'

Now, I can't show you a simple quote from FMCSA for it, but the guy who trained me in at United Rentals was one time hauling a load just like yours down highway 4 near Antioch (East Bay CA, 4+ lane freeway ), and he hit a bump, one of the control boxes bounced off the rail, landed on the Deadman pedal, activating the Raise control. He hit a multi lane overpass with it at 60 mph, destroying several lifts...

They got a bill not long after for the cost of replacing the overpass.
Actually, there had been several strikes to that bridge that had damaged it, so they split the cost between the several companies lol

This may sound impossible or unlikely, but it is not uncommon.
And unless you have verified that every lift is shut off with the key out, is it worth the chance for an extra chain?

I can't remember the source, but I have a hazy memory of some rule or law or official Interpretation that called out specifically that hydraulic devices had to be mechanically secured to within legal limits.
It may be some California thing, or just my conclusion, but I believe it is common sense, since such things do happen.

Oh, and the guy was still working there after that, because he was the assistant manager, so driving wasn't his main job lol

 

Which bridge was it? It shouldn't be any problem to look that news story up.

 

Sorry, wasn't meaning to come across as saying you were wrong, was addressing the general issue, and trying to answer your question why a crane is handled differently than an excavator.

I can't say that all hydraulic cranes have a mechanical brake on the Hoist winch without further research, but I believe they are required to. Osha references an ANSI Standard, but you have to pay to read them, but osha does specify it has to be able to hold the load, and be adjustable for wear.
I am pretty sure when I was involved more in crane work I did see that specifically, but I would have to go over to the crane section at Heavy Equipment Forums to get an answer on that! Lol

I was curious, so I went to Grove, and pulled up the specs on their smallest RT crane, and it has a mechanical brake on it. I am pretty sure the rest do too.

It is mechanical, as in, spring applied, not just a valve on a hydraulic motor. It is automatically controlled by the hydraulic pressure, but when the pressure is removed, the brake holds it.

I don't have a reference to an incident I can offer, but since often excavator booms are only a few inches below bridge height, it shouldn't be hard to picture a bit of bounce causing the bucket to roll, and leveraging the boom up a little.
I have seen this movement enough times with poorly secured excavators, that if it was combined with a low bridge, it could cause contact.

I do admit I have no source for that specific wording, but it is just a rewording of the basic Securement rules, applied to heavy equipment.

Oh! I just remembered something.

California Vehicle code 35250. "No vehicle or load shall exceed a height of 14 feet measured
from the surface upon which the vehicle stands, except that a
double-deck bus may not exceed a height of 14 feet, 3 inches. Any
vehicle or load which exceeds a height of 13 feet, 6 inches, shall
only be operated on those highways where deemed to be safe by the
owner of the vehicle or the entity operating the bus.

35251. (a) A boom or mast which is designed to be raised and
lowered by hydraulic mechanisms and which is a constituent part of or
an attachment to a vehicle or machine, shall be securely chained or
otherwise restrained to ensure compliance with Section 35250 while
the vehicle or machine is being transported as a load or driven upon
any highway.
(b) Subdivision (a) does not apply when the configuration and
design of the hydraulic boom effectively restrain the movement of the
boom during transit."

So, while I know you guys that don't do California will scoff at me, I do have a source for what I was remembering! Lol
And in any case, I am coming at this subject from a common sense, look at the failure modes and redundancy, and make it safe, rather than a specific quote.

 

This was 15 years or so ago, but I think it was the Railroad Ave bridge over hwy 4. I later delivered equipment there during the new bridge construction lol

 

Well I think you missed the whole point of the original discussion. I guess I was referring to a winch dog like an older crawler had. I've helped replace holding valves and was explained to me they hold the drum if they have a spring brake (at least a grove appears to) I stand corrected. My question about crane boom versus excavator booms was mostly rhetorical I understand the difference. Most of us don't deal with or give a crap about California and their rules don't apply in the rest of the country I would still like to see a picture of an excavator that bounced and hit a bridge.

 

I'm not actually that concerned I just find the plausibility of the control landing on the deadman pedal and moving the raise lever which generally requires you to lift a collar on the lever or some other secondary action to move the raise lower lever and lifting it up to hit a bridge pretty far fetched.

 

I can't find a picture of the style controls we had back then, but it was something similar to this one, although I think the Lift switch was on the front face of the box, right where it could easily hit the edge of the Deadman pedal.
And being rental equipment, it was not uncommon for the little plastic side guards to be broken.

The Drive control, and often the Boom controls on bigger machines do have the mechanical lockout collars, but the lift control on a scissor lift usually was just a switch. Some of them didn't even require the Deadman pedal to be pushed to go up and down.

I remember when I was working construction, the carpenters up in the genie lifts screaming when their toolbelts would catch the switch and they would drop unexpectedly lol

So if this was one without the Deadman interlock, and a switch like this, it is a little easier to see this happening.

In any case, I remember the other guys giving him a hard time about it, so it wasn't just a story he made up to scare me into tying down better!