Skilifts.org / SORT Forum

For the record it is NOT a safety bar. It is either a foot rest or a comfort bar.

RibStaThiok, on 30 December 2016 - 11:41 PM, said:

There is plenty of speculation in the news reporter's article. I have been around lifts for 13 years full time and chairs don't swing side to side from speed changes. They go up and down.

The three things that typically make a chair swing on a detachable is wind, the riders goofing around, or a violent stop with a fully loaded lift (very rare and done with load buckets).

Respectfully, I don't like that thought either. But until it is eliminated, it is a possibility, especially in this day and age now where a parent will kill the other and their children and then themselves in murder-suicide. It's becoming more and more common :( Less than a month ago we had such an incident take place here in Littleton/Lone Tree where a mother checked her 2 kids out of school, drove over to a vacant building, shot both her kids, and then herself. I'm sure somewhere in the history of skiing someone has commited suicide by jumping off a lift. Was it the cause here? I don't know. Just a possibility.

Per post on the Granby facebook page, investigation ongoing and lift remains closed. I bet it gets cleared up here within the next day or two.

Eyewitness Account: http://unofficialnet...all-in-colorado

A few things can be inferred from that report ...

1) this is the first witness statement of any kind of "bump" or "jerk"
2) the kids were likely not fighting or horsing around (witness would have likely noticed and reported that)
3) it was likely not a suicide on the part of the mother (witness would have likely noticed and reported that)

Somehow, in some way, that chair whacked a tower ... puzzling, and perhaps explains the long shutdown of the lift.

_litz, on 03 January 2017 - 05:44 PM, said:

Edited January 9,2016. Colorado Passenger Tramway Safety Board released a report on the causes of the accident. Out of respect for the people riding this chair, who, the board says were not contributing factors to the accident, I am deleting my comments about possible causes of the accident.

whatever it was that caused this accident , the answer will be found by the Colorado tram board safety people.
This post has been edited by Andy1962: 09 January 2017 - 06:55 PM

I can pretty much guarantee you that if someone sitting in a chair got a ski or board caught on a tower, it would not stop the chair in its tracks ... it would knock the person something fierce, possibly unseat them ... but not stop the chair. Those grips are like iron.

You'd get some pretty good swing out of it, but that chair's gonna keep going uphill. In a contest between a human body, and the size machine that is a modern lift, the lift is going to win every single time.

_litz, on 04 January 2017 - 08:39 PM, said:

agreed. edited my original posting for clarification, though a bit long winded.sorry - early morning - no breakfast yet

Still shut down.

http://www.thedenver...ll-still-closed

This has gone on long enough you really gotta wonder what's going on ...

If this was a fluke accident (passengers causing the chair to swing, issue with that particular carrier, etc) that lift would have been back in operation days ago.

_litz, on 06 January 2017 - 04:54 PM, said:

Not if there is a full investigation going on.

Seems like most people want information these days immediately... why don't you just sit back and give it some time and let the investigation run it's course. I for one would not speculate, figuring shit out is much better than guessing. Here's to getting it right. Jus my 2ct.

Lift re-opens tomorrow, but ordered to operate under diesel operation.

http://www.9news.com...ident/384584266

Peter, as usual, has an article on the situation :

https://liftblog.com...-dynamic-event/

I had no idea "line dynamics" could make a chair swing side to side ... I always figured forward/back or perhaps up and down ...

'nother question .... this is for the technical guys around ...

What are the differences between the electronic drive system, and the diesel drive system, that make one suspect and the other safe?

The electric drive system converts electrical power into mechanical power. The electric drive (I'll assume a DC drive) converts 3 phase 480 volts alternating current into a DC power source and powers a DC motor. The electric drive has the ability to "give it the coals" in a fraction of a second. If the feedback system for the electric drive isn't working correct, the DC motor can "surge" and speed up excessively. There are typically backup safeties that monitor the electric drive to make sure the drive/motor is behaving.

The diesel drive system uses a large diesel engine to run the lift. A diesel engine is slow to respond and it can take lots of seconds for the lift to get to commanded speed. A diesel can't "surge" like an electric motor, but it can overspeed once boost is built up.
This post has been edited by 2milehi: 09 January 2017 - 08:49 PM

Ok, so I guess either drive system, then connects to the actual mechanicals (gearbox, etc) that spin the lift?

Is the diesel connected through some kind of clutch/transmission setup?

That's an interesting (and complicated) setup; to me the simpler (and more reliable) setup would be a straight electric drive, off of either line power or a diesel generator.

either way, I could see how a direct electric motor drive connection like that could "surge" like you describe; the dynamics of such a thing travelling up and down the rope becomes more understandable ... just think Slinky ...

Depending on the drive line design the Standby or auxiliary drives usually have either a torque converter some other transmission device installed. Remember an IC engine cannot produce full torque at all speeds so it will need a mechanical advantage over the electric motor that can and is often directly connected to the gearbox.

Peter has updated his post on this issue with the following information:

Quote

anyone have any information on what an ABB drive is (or why it might be unsuitable here)?