A Little OT, perhaps

Ski lifts usually have two brakes, a Service Brake which is located near the motor (input side of the gearbox) and an Emergency Brake which acts directly on the rim of the Bull Wheel. Both brakes are fail safe in that if the power is removed, the brake will be applied. The Emergency Brake is not used for normal stopping but only used for fault or emergency conditions.

All Ski Lifts have some form of rollback prevention. Some have a mechanical arrangement which physically prevents the lift from rolling back and others have rollback detection which will apply the Emergency Brake if the lift starts to roll back. The rollback detection will operate after only a few inches of rollback. Clearly some of the safety systems were not working on this lift.

Doppelmayr is a European company who is a world leader in ski lift manufacturing. They have lifts all over the world including many in North America. I am sure there was adequate safety systems designed into the lift but if it is not maintained properly, accidents will happen.
 
"How far do you figure those rocks are going to fly ?"

"This rollback test ? They'll fall right by our feet."

"Cool. Wouldn't want to crowd the camera."
 
Don't say "It couldn't happen in the US". In 2015 the King Pine lift at Sugarloaf Maine suffered a serious rollback incident due to a gearbox failure which rendered the service brake and high speed antirollback inoperative. The drop dog antiroll back looks like it sheared one dog, and that was it. The lift reversing should have automatically tripped the bullwheel emergency brake, but that didn't happen either and the lift only stopped (slowly) after the operator manually engaged the emergency brake.

https://m.youtube.com/watch?v=Jys_iGDpfw8

http://www.sugarloaf.com/Documents/...loaf King Pine Rollback Technical Report .pdf

In the US lifts are regularly inspected, and usually the brakes are checked for operation very frequently. It's unlikely that these incidents happen, but sometimes everything lines up. The lift in Georgia wasn't that old (2007) and was built by a top manufacturer, so I imagine it came equipped with all these safety devices. Whether they were tested or maintained (brakes adjusted and shoes replaced as required) I don't know.
 
I noticed that the direction of rotation of the bull wheel in the Georgia lift was opposite that of the one in the destructive test. The direction of the one in the destructive test is the same as all of the lifts I have ever paid any attention to, that is, when looking at the lift from the bottom of the hill, the up-going side is on the right. The Georgia lift had the up-going side on the left. Do lift manufacturers typically offer left hand and right hand versions? For sure the stop dogs on the bull wheel won't work if it is being operated in the reverse direction than what it was designed for.
 
I noticed that the direction of rotation of the bull wheel in the Georgia lift was opposite that of the one in the destructive test. The direction of the one in the destructive test is the same as all of the lifts I have ever paid any attention to, that is, when looking at the lift from the bottom of the hill, the up-going side is on the right. The Georgia lift had the up-going side on the left. Do lift manufacturers typically offer left hand and right hand versions? For sure the stop dogs on the bull wheel won't work if it is being operated in the reverse direction than what it was designed for.

I don't know what's normal, but around where I am in NY there are quite a few that have the up-going side on the left as you're riding up the lift.
 
From a german news site: There was a power failure, and the system was powered with a diesel emergency power system where a "human mistake" was made.

Guessing: Wrong rotating field when connecting the generator? But why not powering it off if it's running backwards?
 

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