Skilifts.org / SORT Forum

Winterhighland, on Jun 11 2007, 04:57 AM, said:

No, there other forces and they are present in all sheave train setups

Hey I was almost right! Chasl - we have the same Mueller setup with smaller bullwheels. At the top, the gauge reduction is done in one tower - and the bottom it's done in three.

Thanks for the answer about wind loading, now that I think about it that makes sense. I guess the limiting factor of turn angle is the ability of the grips/grip arm to pass smoothly over the sheaves on a line turning away from the centre line, why Poma surface lifts can do dog leg turns with less complex structures than the chairlift on page 1 of this thread.

I've never really thought much about this, but now that I have I realise this canting of sheaves to turn a haul rope is nothing new, the Coire Cas T-bar on CairnGorm Mountain in Scotland is an old Mueller lift built in 1962 with a split line, the downline is straight, but the upline is a long banana shape, the upline heads off at quite an angle from the downline at the bottom drive terminal and the upline is turning on almost ever tower.

My attachment shows a view of the line turning looking up the run, the linked to photo shows a zoomed in view from a mountain on the otherside of the glen and shows what's going on with this ski tow nicely.

http://www.amanita-photolibrary.co.uk/phot...as_3301_std.jpg

I remember I read this theme, and Floridaskier talked about Silver Strike Express at Deer Valley has turns. Last week, I rode that lift and I finally noticed the line of towers, haul ropes is not straight. It made me interesting. The Towers #2, #3, #4, #5, #6 and #7 have sheaves turns. After #7, all are straight. Floridaskier is correct that the lift is avoid from the condo building stands (right side in first picture). I would show you the pictures that I took.

Up:

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Down (look at the bottom station stand left side)

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Tower #2

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This post has been edited by Skiing#1: 12 March 2008 - 07:13 PM

Tower #3

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Number of downloads: 58

Tower #4

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Tower #5

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Tower #6

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Tower #7

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Question,

By having a lift turn via sheaves does add stress / more wear to the liners or not?

Only if the load on those sheaves is higher than normal or the alignment is incorrect, both of which problems are present in normal applications. Otherwise, no.

Also note that on a standard tower arrangement you would normally only be concerned with in and out alignment.
When a series of towers are offset purposely you also have to worry about the cant of the sheave assembly, towers 5 and 6 show this well.
This is something people that work on older Mueller lifts know a lot about. For this situation, if the sheave assembly is not canted your sheave wear would be greater, if not terrible.
This post has been edited by chasl: 11 March 2008 - 11:58 PM

chasl, on Mar 11 2008, 11:48 PM, said:

Our Mueller has 3 metre bullwheels and 4 metre line gauge. We know this all to well!!

chasl, on Mar 12 2008, 01:48 AM, said:

Also note that on a standard tower arrangement you would normally only be concerned with in and out alignment.
When a series of towers are offset purposely you also have to worry about the cant of the sheave assembly, towers 5 and 6 show this well.
This is something people that work on older Mueller lifts know a lot about. For this situation, if the sheave assembly is not canted your sheave wear would be greater, if not terrible.

Chasl - Not having been around too many of these bends, does the Profile show "Cant Angle" in degrees for each tower?

Dino

Lift Dinosaur, on Mar 12 2008, 02:21 PM, said:

I am unsure on the newer profiles as I have not had to deal with these, but with the current cad programs I would put money that it does. Still the profile is theoretical, unless the tower is perfectly plumb and the tower itself is dead on point, your degree value will change. On the older lifts if you could find the profile good luck.
Once you are on the tower it really is not hard to see what has to be done.
On the old Mueller's it was a little difficult as you had to cant the assembly, run the rope to check your alignment and then add or remove shims until the rope ran thru the center of the sheaves.
I always tried to do this on an older lift for the first time prior to changing liners (as new liners would hold the rope quite well and then you would have to check the alignment every few days until it was correct)
And yes I have gone to at least 2 areas with Mueller lifts and had to cant the assemblies as the area had been running them flat and you could actually see a bend in the assembly from the forces of the rope on the leadin and outgoing sheaves.
If you look carefully at the pictures Doppelmayr has added jacking bolts to achieve the canting. On a Poma system I believe the jacking bolts are still part of the standard system.
This post has been edited by chasl: 12 March 2008 - 12:40 PM

chasl, on Mar 12 2008, 02:37 PM, said:

Once you are on the tower it really is not hard to see what has to be done.
Agreed. The rope and the sheaves will tell you what needs to be done.

I always tried to do this on an older lift for the first time prior to changing liners (as new liners would hold the rope quite well and then you would have to check the alignment every few days until it was correct)
I can not tell you how much I have "preached" this. If you do not align first, the new liner will make the rope track in center, but only until the liner wears.

On a Poma system I believe the jacking bolts are still part of the standard system.
The POMA system with the central axle X and Y Bolts will help with this alignment.

Thanks chasl -

Dino
This post has been edited by Lift Dinosaur: 12 March 2008 - 06:55 PM

The original Thunder lift at J.H. was a Mueller. It had the smaller BW's. The gauge change at the lower terminal occurred within a long depression assembly. We had a heck of a time with sheave wear. Finally Jim Ellis noticed the "tilt" angle of the sheavetrain was completely wrong. Someone had screwed it up back in the "old days" and we never saw the obvious.

Carl

This picture of Skiing#1’s is a classic case of why someone would want to put a turn in the line, they knew the start and the end locations of the lift and there was something in the way, so instead of going over they went around.
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Apparently Poma has a few FG lifts with a smaller bullwheel diameter than rope gauge. I was quite surprised to see this, but on Clipper Ship lift at Mount Sunapee, the return bulwheel is smaller than the rope gauge. Jonni, any insight?

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Number of downloads: 83

And FWIW, detachable Poma lifts have much smaller bullwheels than their line gauge. Only the downhill side is deflected, though.

I haven't ever figured out why, but yes, there were a few (probably quite a few) Poma fixed-grip lifts with smaller bullwheels than line guage. Our two '81 triples are set up this way, the '88 quad I worked on at Crystal was as well, and I'm pretty sure our '85 triple is like that although I'm not that familiar with that lift. As for their surface lifts being set up like that, it takes less energy to turn a smaller drive sheave so almost all of the surface lifts I've seen have a bend at tower 1 or 2 on the light side intering the drive terminal. Most of the ones I've seen have a full-width return bullwheel, though.

I found one video that they turn and it is very interesting. I don't know where the lift is since there is no English, and it is foregin language.

http://youtube.com/watch?v=WG8UN3Asu_U

liftmech, on Mar 21 2008, 08:18 AM, said:

It also allows for the use of a smaller gearbox, meaning $$$$.

Skiing#1, on Mar 26 2008, 08:47 AM, said:

I did some digging around and I think it's this lift: http://www.seilbahnt...s/413/datas.htm