Hello again. I'm a lift mechanic at Loon and I previously posted some info on the gondola deropement. Loon's officials, Stacey Lopes on Channel 9 and Rick Kelley in the article pasted in an earlier post, covered the story well and collectively this thread has filled in some of the details but I think I can clear up the picture.
Sledhaulingmedic, we've always refered to the haul rope coming off the sheaves as a "deropement" and a cabin coming off the haul rope (hasn't happened at Loon) as "cabin came off the haul rope" (even though its never happened at Loon). The media used "Derailment" because it was a more recognizable term that fit the incident well enough. I'm also not sure what terms the B77 code uses.
As stated earlier the deropement was on the downhill side of tower 20 which is on Hannah's Bypass, for those who know Loon. The gondola has 22 towers. Taking the rope off of a single tower, especially when the rope is tensioned, doesn't result in the rope hitting the ground. In this case the rope was still far enough above the ground that the minimum clearance of the suspended cabins was approximately 15 feet as they traveled between towers 21 & 19.
Putting the rope back up on the sheaves with a loaded lift in harsh winter conditions would have taken a long time. A ground evacuation with ropes of 75 guests in 19 cabins including some in isolated, non-skiing terrain would have also taken a long time. Under the conditions described in the previous paragraph it was possible to run the gondola under normal power with the deroped sheaves' switch bypassed. Only empty cabins going downhill passed over the extra long span. It took 94 minutes (normally a 7 minute ride) because we were extremely cautious about the wind.
Today we hoped to open the gondola sometime today but management graciously aloud us to take all the time we needed to fully inspect the tower, sheaves, haul rope and the cabin that hit the tower and it ended up taking all day. NH State Tramway inspectors participated and they gave us the green light to run tomorrow although full inspection of the cabin will take longer.
Re-sheaving the haul rope today took a couple of hours including travel and set up. We used a 3-ton chain come-along (actually two in series to reach the sagging rope). The rope is first lifted slightly above the sheaves and then pulled horizontally into alignment while lowering too. The tricky part is getting all the articulating wheel frames to level off into the same arch of the rope when pulling horizontally. Most of the work was done by one person with a ground person tying equipment to a lifting rope. He was exhausted afterwards.
Thanks for listening, hope to see you out there.
Thanks for clearing that up. It's interesting to hear that the lift could be run with the haul rope completely off the sheaves on one tower. I guess it's a lucky thing that it deroped on the return side and not the uphill side, surely the weight of passengers in the cabins would have made it impossible to run off of the sheave train. A lot of times you see guides on sheave trains that'll catch the haul rope in the case of a derailment to keep it from dropping too far. That's what I assumed happened at first, I don't think the lift could have been run if that was the case..
