^ that's dangerous. at this time-so close to Christmas, Menkes offices will be close and there will be no one to take a complain or take any action.
 
Now I think that it's not turning as a result of the wind. The speed is consistent. Hope that it can be stoped just by shutting the power off. I did my duty and informed the city /311/
 
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Zeiss said:
Now I think that it's not turning as a result of the wind. The speed is consistent. Hope that it can be stoped just by shutting the power off. I did my duty and informed the city /311/
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I was also watching that last night, thinking it looked out of control. Good move calling 311!
 
Tower cranes are left to weather-vane, as it is actually safer than "locking it" against the wind, which is actually quite dangerous. All the crane manufacturers recommending releasing the slew brakes, bringing the trolley in, and raising the hook, before leaving the crane unattended for any length of time. The jib will always follow the direction of the wind, reducing the surface area that is being blown against, and reducing the wind pressure. If the crane was locked, the wind could be blowing against the side of the jib, increasing pressure on the entire structure, and possibly causing a collapse of the entire crane.
 
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wopchop, you are probably right as it makes sense what you say. However , I live in the area and have been witness to all the construction around here, I have never seen crane to spin non stop for hours . There were times when I could see 10-12 cranes from my windows and I noticed that after work all the jibs of cranes were left in the same directions.
 
wopchop said:
Tower cranes are left to weather-vane, as it is actually safer than "locking it" against the wind, which is actually quite dangerous. All the crane manufacturers recommending releasing the slew brakes, bringing the trolley in, and raising the hook, before leaving the crane unattended for any length of time. The jib will always follow the direction of the wind, reducing the surface area that is being blown against, and reducing the wind pressure. If the crane was locked, the wind could be blowing against the side of the jib, increasing pressure on the entire structure, and possibly causing a collapse of the entire crane.
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Years ago, when the Met and the Met Encore were being built on Carlton street, there was a major windstorm, and the crane on the one being built at the time did the same thing - spinning 360 degrees quite quickly. If I recall correctly, both Carlton and I believe Yonge Streets were closed for a while as a result.

In some tight locations, where luffing cranes are used, I believe they are locked into place when not in use, to prevent them swinging into each other. Luffing cranes, with the boom raised close to vertical, would not present as much of a face to the wind as a tower crane. Examples of where luffing cranes appeared to be locked in place, and never moved with changes in wind direction, would be the two cranes that were used for the 621 King Street West (Thompson Residences) project, and currently the two side-by-side luffing cranes at 111 Bathurst and the west side crane of the Musee project.
 
AHK said:
Years ago, when the Met and the Met Encore were being built on Carlton street, there was a major windstorm, and the crane on the one being built at the time did the same thing - spinning 360 degrees quite quickly. If I recall correctly, both Carlton and I believe Yonge Streets were closed for a while as a result.

In some tight locations, where luffing cranes are used, I believe they are locked into place when not in use, to prevent them swinging into each other. Luffing cranes, with the boom raised close to vertical, would not present as much of a face to the wind as a tower crane. Examples of where luffing cranes appeared to be locked in place, and never moved with changes in wind direction, would be the two cranes that were used for the 621 King Street West (Thompson Residences) project, and currently the two side-by-side luffing cranes at 111 Bathurst and the west side crane of the Musee project.
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Obviously if the cranes are position in such as way that they can contact each other, then something needs to be done. But a weathervane position is a safe position, and is actually even more critical on a luffer than a crane with a straight jib. A lot of luffers have come down worldwide because the angle that the jib was left at was not right (it shouldn't be vertical, actually), and the wind blew the jib over into itself, causing a collapse. If you going to lock the crane like you said, you would need to temporarily side brace with load.

All that I'm saying is that a crane free-slewing 360 isn't exactly the danger that you guys think that it is, and the crew has left it that way on purpose.
 
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Zeiss said:
wopchop, you are probably right as it makes sense what you say. However , I live in the area and have been witness to all the construction around here, I have never seen crane to spin non stop for hours . There were times when I could see 10-12 cranes from my windows and I noticed that after work all the jibs of cranes were left in the same directions.
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They are generally left with the jib pointing in the wind direction, and allowed to free slew. That's why you see them all in the same direction.
 
A luffing jib is actually under less tension the closer to vertical it is. That's why their load charts all increase as you move closer to the tower. It would be more stable in a raised position than a lowered one. It's the exact same reason why, on a saddle jib, the best practice is to leave the trolley close to the tower and not out at the end of the boom.
 
whatever said:
A luffing jib is actually under less tension the closer to vertical it is. That's why their load charts all increase as you move closer to the tower. It would be more stable in a raised position than a lowered one. It's the exact same reason why, on a saddle jib, the best practice is to leave the trolley close to the tower and not out at the end of the boom.
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This makes sense. But my understanding is that a luffing jib left close to vertical has almost no ability to weathervane, which increases the stress on the structure during high windstorms, so the crane erectors will come up with some x value radius to leave the jib at, which provides a balance between that tension, the effect of wind on the crane structure, and the possibility of physical contact with other cranes / structures.
 
That would also make sense. I've never seen a luffing jib locked out for the night at 80 degrees, they usually seem set somewhere around 60'ish. The only tower crane that I've actually seen come down was a saddle jib, but I can easily picture a luffing jib folding backwards over itself in high wind
 
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