Any chance you can post them because I can't see them.
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Sugarloaf Lift Accident - 3/21/15
- Thread starter WJenness
- Start date
Any chance you can post them because I can't see them.
Looks like you have to register and login to see the photos. Many of the members on this forum are lift maintenance employees and the others are chair lift junkies.
Exactly. I'd still like to see the pics.
MEDIA ADVISORY: Sugarloaf Rollback Investigation Reveals Apparent Lift Design Issue
MARCH 25, 2015
CARRABASSETT VALLEY, ME - A team of investigators, including Sugarloaf personnel, engineers from Boyne Resorts (Sugarloaf's parent company), and a licensed Maine lift inspector, have completed a preliminary review and investigation of the rollback of the King Pine Chairlift on Saturday , March 21, 2015.
Investigators determined that a fracture of the main drive shaft of the lift's secondary gearbox initiated the rollback, and that the lift's bullwheel brake engaged and operated properly.
Investigators also identified an apparent manufacturer design issue in one of the lift's components as contributory to the accident.
Sugarloaf and Boyne engineers have also identified a retrofit for the system that corrects the issue.
"Our first thoughts remain with those injured, and our sincere hope is for their speedy recovery," Sugarloaf General Manager John Diller said. "I'm grateful that we now have a clearer understanding of what occurred."
Gear Box Failure:
The incident on King Pine occurred at approximately 11:30 Saturday morning, when a shaft in one of the two gearboxes that transfer power from the lift's electric motor to its bullwheel fractured.
The gear boxes in the King Pine lift, along with every other lift at Sugarloaf, were subjected to a routine vibration assessment by an outside contractor the day before the incident, and no anomalies were detected that indicated such a fracture was imminent or likely.
The fracture of the shaft resulted in the loss of both the primary service brake and the anti-reverse brake, leaving two additional braking systems intended to prevent a rollback.
The failure of the shaft, in and of itself, should not have resulted in the rollback that occurred, if the lift's remaining systems had performed as intended.
Bullwheel Brake Activation:
Though further investigation is still needed, findings suggest that an automatic system to activate the lift's bullwheel brake (identified as "emergency brake" in previous statements) activated properly. Additionally, the lift's operator quickly activated a manual control to apply the bullwheel brake.
Bullwheel brake activation is, by design, not instantaneous, because an immediate stop of a moving lift can create sudden and dramatic movement along a lift's haul rope, potentially causing enough movement to cause skiers to fall out of chairs, a deropement of the lift, and other significant damage.
In the time between bullwheel brake activation and the actual stoppage of the lift, the lift traveled backwards for a total of nine chair lengths, or approximately 460 feet, due to the weight of skiers on the lift, which was full.
The investigators also found that a further system to prevent a rollback failed, due to an apparent design flaw.
The Drop Dog:
The final system intended to automatically engage to prevent a lift rollback is commonly referred to in the ski industry as a "drop dog." Lifts are required to have some form of device to prevent the lift from counter-rotating, and variants of the drop dog approach are generally used today.
The investigation revealed that one of the switches used in the safety circuit connected to the drop dog was an inappropriate switch for the intended application. This switch, which is designed to suspend the drop dog above the bullwheel when it senses forward rotation of the lift, can also suspend the drop dog when the lift rotates in reverse.
This switch was provided by the lift's original manufacturer, and is still provided by the company that manufactures components for this type of lift.
The investigation indicates that, had an appropriate switch been included in the system, the drop dog would have deployed and the rollback would have stopped immediately.
Sugarloaf personnel and Boyne Resorts engineers, along with a licensed Maine lift inspector, have designed circuitry to correct this situation. This modification has been reviewed and approved by the State of Maine, and is being installed on other lifts at Sugarloaf that employ the same type of switch.
There are six such lifts at Sugarloaf - Skidway, Sawduster, Snubber, Double Runner East, Double Runner West, and Bucksaw. Upon reaching the above conclusions regarding the drop dog switch this morning, and acting on an abundance of caution, Sugarloaf personnel made the decision to temporarily shut down the Skidway, Sawduster, Snubber, and Double Runner lifts until the modification was installed. The Bucksaw lift was not scheduled to operate today or tomorrow and will be modified before it is operated again on Friday.
Sugarloaf and Boyne Resorts have been in touch with the lift's parts manufacturer to share their findings.
MARCH 25, 2015
CARRABASSETT VALLEY, ME - A team of investigators, including Sugarloaf personnel, engineers from Boyne Resorts (Sugarloaf's parent company), and a licensed Maine lift inspector, have completed a preliminary review and investigation of the rollback of the King Pine Chairlift on Saturday , March 21, 2015.
Investigators determined that a fracture of the main drive shaft of the lift's secondary gearbox initiated the rollback, and that the lift's bullwheel brake engaged and operated properly.
Investigators also identified an apparent manufacturer design issue in one of the lift's components as contributory to the accident.
Sugarloaf and Boyne engineers have also identified a retrofit for the system that corrects the issue.
"Our first thoughts remain with those injured, and our sincere hope is for their speedy recovery," Sugarloaf General Manager John Diller said. "I'm grateful that we now have a clearer understanding of what occurred."
Gear Box Failure:
The incident on King Pine occurred at approximately 11:30 Saturday morning, when a shaft in one of the two gearboxes that transfer power from the lift's electric motor to its bullwheel fractured.
The gear boxes in the King Pine lift, along with every other lift at Sugarloaf, were subjected to a routine vibration assessment by an outside contractor the day before the incident, and no anomalies were detected that indicated such a fracture was imminent or likely.
The fracture of the shaft resulted in the loss of both the primary service brake and the anti-reverse brake, leaving two additional braking systems intended to prevent a rollback.
The failure of the shaft, in and of itself, should not have resulted in the rollback that occurred, if the lift's remaining systems had performed as intended.
Bullwheel Brake Activation:
Though further investigation is still needed, findings suggest that an automatic system to activate the lift's bullwheel brake (identified as "emergency brake" in previous statements) activated properly. Additionally, the lift's operator quickly activated a manual control to apply the bullwheel brake.
Bullwheel brake activation is, by design, not instantaneous, because an immediate stop of a moving lift can create sudden and dramatic movement along a lift's haul rope, potentially causing enough movement to cause skiers to fall out of chairs, a deropement of the lift, and other significant damage.
In the time between bullwheel brake activation and the actual stoppage of the lift, the lift traveled backwards for a total of nine chair lengths, or approximately 460 feet, due to the weight of skiers on the lift, which was full.
The investigators also found that a further system to prevent a rollback failed, due to an apparent design flaw.
The Drop Dog:
The final system intended to automatically engage to prevent a lift rollback is commonly referred to in the ski industry as a "drop dog." Lifts are required to have some form of device to prevent the lift from counter-rotating, and variants of the drop dog approach are generally used today.
The investigation revealed that one of the switches used in the safety circuit connected to the drop dog was an inappropriate switch for the intended application. This switch, which is designed to suspend the drop dog above the bullwheel when it senses forward rotation of the lift, can also suspend the drop dog when the lift rotates in reverse.
This switch was provided by the lift's original manufacturer, and is still provided by the company that manufactures components for this type of lift.
The investigation indicates that, had an appropriate switch been included in the system, the drop dog would have deployed and the rollback would have stopped immediately.
Sugarloaf personnel and Boyne Resorts engineers, along with a licensed Maine lift inspector, have designed circuitry to correct this situation. This modification has been reviewed and approved by the State of Maine, and is being installed on other lifts at Sugarloaf that employ the same type of switch.
There are six such lifts at Sugarloaf - Skidway, Sawduster, Snubber, Double Runner East, Double Runner West, and Bucksaw. Upon reaching the above conclusions regarding the drop dog switch this morning, and acting on an abundance of caution, Sugarloaf personnel made the decision to temporarily shut down the Skidway, Sawduster, Snubber, and Double Runner lifts until the modification was installed. The Bucksaw lift was not scheduled to operate today or tomorrow and will be modified before it is operated again on Friday.
Sugarloaf and Boyne Resorts have been in touch with the lift's parts manufacturer to share their findings.
ceo
Active member
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http://sugarloaf.com/x1650.xml
It appears that the drop dog failed because of a design flaw: it's supposed to retract when it detects forward movement of the bullwheel, but it also retracts when it detects reverse movement. Which would be hilarious if it weren't terrifying.
Sugarloaf, to their immense credit, designed a fix for this problem as soon as they figured it out, got it approved and installed it on all of their lifts that used that type of drop dog switch that same day. That's all of the fixies except Skyline and, surprisingly, Timberline (which is identical to King Pine).
They also state that the bullwheel brake's taking 9 chair intervals to stop the rollback is by design. I'm... surprised by that.
It appears that the drop dog failed because of a design flaw: it's supposed to retract when it detects forward movement of the bullwheel, but it also retracts when it detects reverse movement. Which would be hilarious if it weren't terrifying.
Sugarloaf, to their immense credit, designed a fix for this problem as soon as they figured it out, got it approved and installed it on all of their lifts that used that type of drop dog switch that same day. That's all of the fixies except Skyline and, surprisingly, Timberline (which is identical to King Pine).
They also state that the bullwheel brake's taking 9 chair intervals to stop the rollback is by design. I'm... surprised by that.
So the (largely) defunct chairlift manufacturer is to blame? Interesting.
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ceo
Active member
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- Apr 1, 2009
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- 393
- Points
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Might not have been the manufacturer; the two Stadelis (Sawduster and Bucksaw) use the same switch. I wonder if the requirements for it vary enough by jurisdiction that it's a third-party component that's installed when the lift is put in.
Jully
Active member
Looks like they might not be replacing the lift after all!
Good point. The King Pine and Timberline Quads are both Borvigs. There are (and were) other Borvigs there including the infamous Spillway Double.
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Smellytele
Well-known member
The article did say "This switch was provided by the lift's original manufacturer, and is still provided by the company that manufactures components for this type of lift."
fbrissette
Well-known member
This is mind boggling and does not make sense. What is the point of having redundancy if the redundant system was actually never tested ?
VTKilarney
Well-known member
If these facts are correct, it appears that Sugarloaf did nothing wrong and that their training worked perfectly. Hopefully the final investigation proves this to be the case.
I'd hate to be the switch manufacturer and/or the vibration tester. Is it possible that the vibration test could have been performed correctly yet it would not show this fracture?
I'd hate to be the switch manufacturer and/or the vibration tester. Is it possible that the vibration test could have been performed correctly yet it would not show this fracture?
also being completely ignorant of these things, I wonder could it be possible the vibration test caused or at least contributed to the fracture?
SIKSKIER
New member
I dont have any first hand knowledge of this test but I would think the test doesn't actually vibrate the gear box but has sensors that listen/feel for excessive vibration.
VTKilarney
Well-known member
Here is some information on vibration testing:
http://www.bksv.com/doc/BO0233.pdf
http://www.bksv.com/doc/BO0233.pdf
SAM's Press Release on the latest development:
http://www.saminfo.com/news/faulty-switch-contributed-sugarloaf-lift-rollback
http://www.saminfo.com/news/faulty-switch-contributed-sugarloaf-lift-rollback
machski
Well-known member
King Pine and Timberline are not identical. KP and when it was Whiffletree FGQ were identical. When Whiffletree was removed and reinstalled as timberline in the 90's, it was completely overhauled with all new hardware and systems. That is why it was not on the switch list. My understanding is that Sunday River has made switch changes on 2 lifts as well from this, I would guess they would be Locke and Spruce as those are the only Borvigs left on the mountain.
