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This is on a chair from Whistler that is in the sun valley boneyard...

So looking at these pics, I'm woundering were the design flaw is. What is it about these grips that caused them to fail.

The grip that you're looking at is the only Yan detachable grip that had problems, while the Type 7 had no reported probelms. However, resorts still freaked along with the government and had their yan detachables retrofitted or replaced entirely. The reason why the Type 11 grip failed was because it couldn't support the extra weight of the bubble that was it supposed to be designed for and it failed.

The main flaws cited in the accident report from Whistler were, in no particular order:
-Rubber springs which could not adjust for temperature swings (rubber gets hard and brittle when cold)
-The use of steel wedges in the grip to allow for different rope guages. Most grips have several different jaws machined to the precise diameter of a given rope; Yan hoped to avoid that by supplying these wedges instead. The wedges on the affected grips were worn to the point of allowing less jaw contact with the rope.
-The nominal grip force applied by the grip was supplemented by the weight of the chair. During a stop or start, the line of almost any lift has a tendency to bounce; at the apex of any bounce, there is a moment when the weight of the chair is eliminated from the equation. This is the same principle used by NASA in their 'zero-gravity' astronaut training flights. Once that weight is out of the picture, the grip force is lessened by just that much.
-The allowable swing on that particular series of grips wasn't much more than 30 degrees or so, while the steepest section of the Quicksilver was around 40. Thus, the carriers actually rested on the forward or rear swing stop and tried to pry the grip off the rope.

Hope this helps.

I don't really understand how the Yan grip worked. When it opens, what part moves? I see the famous marshmallow springs, but I can't think of how they translate into grip force

SkiBachelor, on Apr 5 2006, 07:28 PM, said:

The YAN 7 grips had most or all of the same design flaws I listed above. The YAN 11 was supposed to be beefier than the 7, mainly for the bubble but supposedly for better durability. I hadn't heard that the extra weight of the bubble had anything to do with the accident, but it's been a while since I read the report and it could have been in there somewhere.

floridaskier, on Apr 5 2006, 07:39 PM, said:

YAN 7 and 11 grips had not one, but two mobile jaws, hence the two levers sticking up from the grip body. They were hinged on either side of the shiny strip in the middle. The marshmallow springs were inside the squarish frame on top of the mobile jaw levers, and they pressed the jaws down and in towards the rope. The compression rail(s), unlike in a Poma or Doppelmayr, pressed the mobile jaw levers inward towards each other which opened up the grip.

Remembrances –
This style of grip did have some good features - notice the wide aggressive traction plate, hourglass rollers (for self cleaning rails), split fingered needles (for smooth hold down sheave transitions), smooth short grip (just as smooth riding as a Riblet), and very few movable parts.
The other stuff – the grip did not "wrap" enough of the haulrope. The terminal transitions – level to angled, and from attached to detached were very short – not so bad for detaching but not so good for attaching or detecting a miss-attached grip. Those two detriments were impossible to financially overcome. Also early codes, reviewing engineers, area owners and lift inspectors did not address either of those issues adequately – of course ultimately the blame will go to the manufacturer.

For more information you can also try our search function – try Polx – West, YAN HSQ, YAN Detachable etc.

Its a shame that the grips had the problems, the Yan HSQs are the best looking lifts in my opinion. Unfortunately the only pure Yan HSQ that I got to ride was Friendly Giant.
This post has been edited by poloxskier: 05 April 2006 - 09:26 PM

How many bubble chairs were built?

Only 1 to my knowledge.

poloxskier, on Apr 5 2006, 11:30 PM, said:

Beauty is in the eye of the beholder. I'll bet you never worked on one of these. Any work that needed to be done on the accelerators, decelerators or conveyers was done outside, in the elements. To change terminal tire, you had to remove it's gearbox but since there was no terminal, there was nothing to lift it with. There wasn't really any way to get at the coupling/uncoupling areas except from underneath. Same with the driver wheels. To take a chair offline, you had to remove a section of the turn around rail and lower the chair to the ground with winch. Yan had some good ideas but those terminals sucked from a mechanic's point of view. They certainly inspired a lot of aftermarket creativity for us to get around these issues...

barnstormer, on Apr 6 2006, 08:09 AM, said:

My opinion is strictly based on outward apperances and not from working on one. I didn't realize that they required so much extra work to do something that seems relitively routine like changing a tire. I can definately see how the things you mentioned allong with accidents led to them being removed or modified quickly.
This post has been edited by poloxskier: 06 April 2006 - 10:06 AM

I remember hearing about how on a warm day with rain and then a freeze, the ice would get inside the turnarounds and acceleration/deceleration areas and freeze them solid. Did you ever have this problem, barnstormer?

I'm not a big fan of how Yan HSQs look. I really don't like the bubble chairs. The Y towers are cool looking though, much better on the quads than they are on the triples. But I can see that some people would like the designs better, at least from an aesthetic point of view

Here are some more pics of the old yan hsq parts in the sun valley boneyard. They have the 7 Yan motor rooms lined up. Each motor room has all the original equipment inside, plus shelves full of extra parts.

gearbox  svlifts_003.jpg (988.87K)
Number of downloads: 108

yan bubble chair from whistler with yan motor rooms in background  svlifts_025.jpg (1.5MB)
Number of downloads: 145

yan chairs  svlifts_034.jpg (1.77MB)
Number of downloads: 134

chairs and motor rooms lined up  svlifts_037.jpg (1.54MB)
Number of downloads: 100

control boxes  svlifts_013.jpg (909.34K)
Number of downloads: 62

motor rooms from behind  svlifts_023.jpg (1.05MB)
Number of downloads: 112

Wow, it appears that Sun Valley purchased all new Yan carriers for its HSQs just because they replaced the lifts. That's probably why Christmas (didn't have them in 88 when the lift was installed) and Frenchman's have them. I would think some of the other resorts like Pico, Mt. Snow and K-Mart, Sunday River would like to purchase some and put them on their Yan HSQs. These carriers are really nice and comfy.

Now that we've seen pictures of the Yan 11 HSQ grip, does anybody have pictures of the Yan 7 HSQ grip?

Hi Skier2, checkout this link:

http://www.skilifts....?showtopic=2249

Where is the boneyard located in Sun Valley?

It is below the bottom of the Cold Springs lift. There is a dirt road up to it from the new medical center off of the highway. I got to it from the cold springs mountain bike trail, which passes right through it.

OK great, thats what I thought. I used Google Earth and was able to track it down.

Thanks!