Crane drops restored A4

[Bryan]

I was a bit worried when I saw this filmclip title.

http://www.youtube.com/watch?v=CLC-QgCi ... re=related

[2002EarlMarischal]

Ouch!

Agreed that's not a good thing for ardent Gresley fans to read!

The crane company didn't do their homework did they?

[Blink Bonny]

Ay up!

Scratch one Skyhawk!

[mr B]

good old uncle sam - if yer gona do it , do it US style


mr B

[52D]

A4 the A stands for attack, a well liked light weight jet from the USA.

[Coboman]

Ouch!

Agreed that's not a good thing for ardent Gresley fans to read!

The crane company didn't do their homework did they?

What I don't understand is in the UK when you get to 90% of a cranes max capacity alarms sound. In that video, you cannot hear any alarms sounding, just the sound of failing metal which resulted in the crane toppling. Do the Americans not have any safety features on their cranes?

[52D]

US cranes do normally have safety systems such as the Wylie built in although they can be (Illegally) shorted out. Certainly the US built cranes in use at RAF Mildenhall have an overload alarm and under US H&S legislation they have to have an annual test of the system. This does not have to be the maximum safe working load.
Normally in the cab of every Mobile crane there will be a chart showing what load the crane can lift at a particular radius. For example the cranes i was involved with were rated at 15 Tons at minimum radius (ie almost vertical jib) for every foot from the centre point of the jib pivot the safe working load will be lower. The Wylie system calculates this and will give an audible warning and refuse to allow the crane to operate.
When we tested the cranes, i used to fetch 3 Tons of test weights and set them on the ground at the distance on the chart where the crane should be able to pick them up. We then attempted to pick them up. If they picked up we would then move the jib outwards waiting for the alarm to sound and the Wylie to cut in.
If the alarm and cut out didnt work the Wylie was either faulty or required recalibration.

Note the use of Tons and feet still in use in the good old USA, you have to watch though as the crane was rated in US or Short Tons not Tons(IMP) or tonnes.

[Bryan]

I don't think it was an overload problem as a comment in the clip says the ground gave way.

That seems to be a common problem, though, in the states.
Wasn't there a clip last year of a bridge being put in place and the crane toppled when the ground gave under it?

[52D]

I didnt watch the clip so sorry for waffling on about overloads and testing but ground giving way isnt new either. A colleague was once erecting stacker cranes at a well known confectioners in Slough and had it in writing that the ground was good enough for the mobile he was bringing in.
Result one of the largest mobiles in Europe at the time up to the axles, two slightly smaller (but not by much) mobiles eventually got it out.
The closest ive come to disaster was not in the UK (The law doesnt let you take chances these days, you need lift plans and an appointed person to supervise the lift.) was in Saudi Arabia where a suitable crane couldnt be located anywhere close to the job. I took a chance and the load stopped on the ground and the mobiles rear wheels started to come up. Load was loosed off pretty quick and i laid a temporary road of sleepers to get the crane closer. Old school Riggers are invaluable for problems like this. I had to learn the hard way.

[Postman Prat]

I saw the result, in Hull docks, of someone using a 20' frame and wire strop type spreader to pick up a 40' container. The container was only suitable for use on a Banana Boat after that!!!!