Just curious, what would happen if an aerial tram cable just snapped? is there any device that would stop it from rolling back. My other question is, When the descending car at Grouse goes over the top tower, it seems to speed up, and then slow down, and the faster the tram goes, the worse it is, and when watching from the bottom of the tram, the haul rope of the descending car drops (slackens) quite noticeably. Normal or should I be concerned?
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Aerial Tramway Safety
Started by Whistler, Mar 27 2005 05:31 PM
7 replies to this topic
#2
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Posted 27 March 2005 - 05:52 PM
I'm not sure if you remember the tram accident that happened over in Italy about 6 years ago when a U.S. fighter jet was flying up a valley and sliced a trams haul rope and track ropes causing the cabin on that side to fall to the ground killing everyone. However, the other cabin didn't fall because it's track ropes were still in tact, although it's haul rope was sliced by the plane. However, if the haul rope snaps, there are brakes on the carriage that will clamp down on the track ropes and the cabin(s) will stop.
The reason why the descending cabin speeds up after it goes over a tower is because of the extra slack in the haul rope, which is caused by many things. Think of a rubber band, when there is no physical force on it, it's size doesn't change. However, when you start to stretch it out, the rubber band gets bigger to compensate for that extra force. This is the same type of thing that happens with trams. There can also be more slack in the haul rope on warm days compared to cold since metal is easily effected by heat.
The reason why the descending cabin speeds up after it goes over a tower is because of the extra slack in the haul rope, which is caused by many things. Think of a rubber band, when there is no physical force on it, it's size doesn't change. However, when you start to stretch it out, the rubber band gets bigger to compensate for that extra force. This is the same type of thing that happens with trams. There can also be more slack in the haul rope on warm days compared to cold since metal is easily effected by heat.
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#3
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Posted 27 March 2005 - 07:46 PM
When the haul rope goes from hauling to retarding the cabin speed, there will be a shift in actual cabin speed while the slack is taken up (even though the rope speed at the bullwheels will remain constant).
When the cabin is being pulled, there is little load (only the tensioner) on the return side of the haul rope. When it passes over the top of that tower, and the cabin goes from needing to being pulled to needing to being slowed, it will take up the slack in the return side, and the haul side becomes the side with no load. The cabin will move as fast as gravity and the rope as it shifts into its new slack positions will allow.
-Iain
When the cabin is being pulled, there is little load (only the tensioner) on the return side of the haul rope. When it passes over the top of that tower, and the cabin goes from needing to being pulled to needing to being slowed, it will take up the slack in the return side, and the haul side becomes the side with no load. The cabin will move as fast as gravity and the rope as it shifts into its new slack positions will allow.
-Iain
#4
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Lift Sparky
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Posted 27 March 2005 - 07:56 PM
Not all trams have track rope brakes. See Doppelmayrs World Books. There are some interesting code rules about them in some jurisdictions I believe.
Rob
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#5
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Posted 27 March 2005 - 08:29 PM
I think the Grouse Tram has one...there is a red lever that says "Emergency Brake" in the cabin...Is that the only way to engage it? manually?
#6
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Posted 28 March 2005 - 08:15 AM
I would sure hope not! I'd also hate to see someone yank that while the thing was in operation. Not sure what they do for communications on that stuff (It's been a while since I've riden a huge ropeway like that), but if the drive wasn't shut down that'd make a mess.
-Iain
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#7
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Posted 29 March 2005 - 04:39 AM
From what I remember of the Grouse tram, the 'emergency stop' cord manually applies the cabin brake. I don't think applying the brake wile the drive is operating is an issue, Iain; if the cabin is truly out-of-control either the drive has broken down or the gearbox has disintegrated or something like that.
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#8
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Posted 29 March 2005 - 05:00 AM
No - I meant, for someone to yank on it while the thing is operating just fine. Haul rope hauling something that won't be hauled = bad. :)
-Iain
-Iain
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