33 replies to this topic

[ski lift maniac]

At the amusement park that I work at we have a chairlift, and when I have worked it I have always been told not to let anyone ride around the bullwheel, which is fine, but the reasoning for this is that the haul rope will fall off the bullwheel. Is this true, I have read stories of riders going around the bullwheel and hitting the stop gate (which this lift does not have) but could a rider going around the bull wheel really derope the lift?

[Keymech]

I to have been told this myth, so I have tried it on a few lifts, with the workchair in the summer loaded, slowly. and watched to see if the rope would even leave the B.W. liner groove. It did not, on the lifts I have done this to.

[Allan]

On one of our lifts the rope will come out of the liner groove and rest on the lower flange when we ride around with a loaded work deck... always goes back into the groove though. Never enough weight on a chair though.

[floridaskier]

At Sundance in the summer, they slow it down and let people ride around the bullwheel on Ray's Lift, a mid-90s CTEC fixed quad, so I guess it can be done

[liftmech]

I've long since forgotten who told me this, but I recall hearing that if one were to run a loaded chair around the bullwheel at full speed it could derope the bullwheel due to the added force. I've run loaded work chairs and people who failed to unload around at slow speed and never had a problem. Never tried it at full speed, though.

[Emax]

The earliest load tests that I attended always had the "double load around the bullwheel" test.
A chair was loaded to twice the normal test weight and run at full speed around the bullwheel. The grip would often kiss the upper bullwheel flange, but I never noticed the rope leaving the groove.

Of course, these were all Yan fixed-grips. Other former disciples of the Nevadican may be able to comment further on this.

When you think about it, a fully-loaded chair passing through the bullwheel at full speed is a definite possibility during normal operations. It shouldn't happen, but it certainly can.

[Emax]

mjturley34, on Jun 18 2009, 11:49 AM, said:

What might could or cannot happen when a loaded chair goes around the bullywheel is not the issue. If the machine you work on has a policy of not allowing bullwheel riders then folks should exit the ride before it makes the turn ?

Insurance companies & engineers tell folks not to ride the bullwheel because most lifts are designed to take people somewhere & drop them off. If chairlifts didn't do that nobody would ride them ? If people did not depend on lifts to ski lots of skids would be without seasonal jobs.

I refer you to the original question - which did ask about risk:
At the amusement park that I work at we have a chairlift, and when I have worked it I have always been told not to let anyone ride around the bullwheel, which is fine, but the reasoning for this is that the haul rope will fall off the bullwheel. Is this true, I have read stories of riders going around the bullwheel and hitting the stop gate (which this lift does not have) but could a rider going around the bull wheel really derope the lift?
We must admit that some lifts do return passengers to the point of origin - ones used in New England for "leaf-peeping" in the autumn, those at some amusement parks...

In a sense, all lifts reside in "amusement parks". That's what ski resorts are.

[Jonni]

I know that Lake Compounce in CT has a skyride chair (D/TEC quad) that runs with passengers riding the bullwheel. Although I believe normal line speed is something like 200fpm or so.

[Emax]

I think you're misunderstanding me. I'm not advocating anything.

<ski lift mechanic> simply asked if there was any merit to the explanation he was given for not letting riders to continue around the terminal. The fact is that no lift is designed in such a way that doing so would derope the bullwheel. That would be inviting disaster.

My sub-point was that testing a lift for such a possibility isn't a bad idea - since under some circumstances, a fully loaded chair (passengers or cargo) might do just this - there is no fool-proof prevention for it.

Acceptance testing of lift machinery should (and for the most part does) take into account the worst possible circumstances - since deropement and other imaginable failures can be catastrophic to both the machine and its passengers.

[hoodoo]

I've worked on Yan and Riblet chairs where you could not unload on the light side at the bottom, you had to ride around the bullwheel at when downloading to unload.. on slow. The same at several other FG lifts where you are right up in the turkey shoot if you fail to unload... in winter you can build a "second chance" ramp, but in summer if you run for public they have to go around the bullwheel also.. I have never had any problems with doing this as long as it is on slow... I have had ops that "forgot" about me and I have went around a FG bullwheel at full speed... it was not fun, but nothing adverse happened to me or the lift.

[Lift Kid]

I have had a few younger students in my ski school days go around the bullwheel. As in everyone else's cases, nothing bad happened. Of course, the lifty wasn't awake on one of them and sent a student of mine back down the hill...Little kids always miss the stop gate. But, nothing has happened, although I recall hearing that from a higher-up co-worker a while back.

So is this ski lift myth busted or plausible? That is the question. (any Mythbusters fans here?)

This post has been edited by Lift Kid: 18 June 2009 - 07:54 PM

[Keymech]

BUSTED

[shoemaniii]

I don't believe the rope will come off a properly adjusted and tensioned ski-lift. I think there's too much tension pulling the rope into the bullwheel groove to be affected by someone riding round the wheel at full speed. Chances could be increased on a mis-adjusted flying return wheel, that has a minimum flange extension.

On running doubly-loaded chairs around the wheel during acceptance testing, L/E may have been demonstrating compliance with the following from B77-1982/1999 Carriers-Horizontal Loads:

"Certification of a test shall be provided by the manufacturer that a loaded carrier with twice the design load had been passed around the bullwheel at full speed of a chair of identical design and fabrication without any yielding of the chair tested."
bobp

[cjb]

shoemaniii, on Jun 19 2009, 04:54 AM, said:

"Certification of a test shall be provided by the manufacturer that a loaded carrier with twice the design load had been passed around the bullwheel at full speed of a chair of identical design and fabrication without any yielding of the chair tested." bobp

This makes it sound like the concern is the structural integrity of the carrier, more than the rope staying in position on the bullwheel. I have seen plenty of 'faiure to launches' in which the stop gate is not tripped until the carrier is 1/2 way around the bullwheel and have never seen anything close to a deropement.

[skisox34]

The outpost double at Pico has no bullwheel flange and I rode around at the top and the chair swung violently sideways hitting the outside return support and knocking me to the ground at which point the chair swung back and forth and the top op didn't stop or slow the lift and I was scared it was going to hit the unload station tower and derope the lift. Some older lifts I think that is the case if there is no upper flange to keep the chair from swinging when loaded.

[ski lift maniac]

mjturley34, on Jun 18 2009, 12:49 PM, said:

What might could or cannot happen when a loaded chair goes around the bullywheel is not the issue. If the machine you work on has a policy of not allowing bullwheel riders then folks should exit the ride before it makes the turn ?

Insurance companies & engineers tell folks not to ride the bullwheel because most lifts are designed to take people somewhere & drop them off. If chairlifts didn't do that nobody would ride them ? If people did not depend on lifts to ski lots of skids would be without seasonal jobs.

You would be surprised at the number of people that ask me to ride around the bullwheel and I was told to tell them they cant because it will derail the rope.

[liftmech]

Seeing Hoodoo's reply reminded my that it would be possible for a Riblet carrier to detach itself from the rope if it went around loaded. The normal forces acting on that clip are changed when you figure centrifugal force into the mix. I had a loaded chair pop out of the rope once; rope never left the groove of the bullwheel, though.