26 replies to this topic

[NHskier13]

Yes, I know the title is a little vague.
What I wanted to know is why some lifts are built with towers in which the crossarm (or whatever you call that place where the sheaves are mounted) is not even, or sometimes only having a tower on one side of the line.
I have plenty of examples to show you:
the former Spear Mountain Triple at Ragged (Photo taken in 2013)
 Spear Mountain 2013 Tower 1.png (1.34MB)
Number of downloads: 148
The Tiger Triple at Gunstock (Photo taken in 2013)
 Tiger 3 Tower 10 feb 2013.png (853.56K)
Number of downloads: 205
(photo needed to be cropped due to large file size)
I actually found out the more proper term for this lift is an "offset tower" on the Aurora Peak Quad at Sunday River:
 Aurora Peak Quad Tower 1.png (1.86MB)
Number of downloads: 176
Also another lift on this mountain has an uneven tower, similar to that of the Spear Mountain Triple. This is the Little White Cap Quad at Sunday River :

So, is there any particular purpose having the line be uneven serves?

[Yooper Skier]

Technical note - the picture of Aurora is Tower 2. Yan reserves towers 1 and sometimes both 1 and 2 for the portal

[DonaldMReif]

Snowflake at Breck has several of these towers due to the different profiles of the uphill and downhill lines between just before the midload station and just above the 45 degree turn

[Backbowlsbilly]

I know that sometimes on fixed grips it is done because there needs to be a hold down assembly on the uphill side that isn't needed on the downhill side, like Red Dog at Squaw.

[ceo]

The King Pine Quad at Sugarloaf has one of those. I don't have a picture, but like a lot of others, it's a compression tower for the uphill side only.

I saw a pair of parallel Poma surface lifts at Serre-Chevalier in France that had a common uphill-side-only tower between them.

[teachme]

I understand one reason is that it allows for rope evac to be possible if the line on the uphill side is lower (Assuming no download cap).

[william b]

In the case of the Spear Mt. Triple at Ragged Mt., the concern was for the portal sheave unit loading at the drive terminal, which is fairly close. This being the incoming side, and the lift being a bottom drive, the tension and tower loading was such that the decision was made to lower the downhill crossarm at the tower to reduce the rope angle and portal sheave unit load coming into the drive terminal. Please correct me if I'm wrong, tramway guy.

wbl

[Tramway Guy]

I don't remember why that was done exactly, but remember most of that lift came from relocating from King Ridge, so we were working with what we had. And that certainly makes sense. The tension difference between uphill and downhill line makes for a huge difference in loading when you put wrap in the rope.

[SkiDaBird]

With the offset tower, Cecret has 2 I believe and I'm fairly certain they are due to ground terrain in the area. There are a lot of little creeks through that area, that ultimately form Little Cottonwood Creek.

[RibStaThiok]

Alta had/has a few of them. I remember the first time I skiied there when I was just a little fresh 12 year old Boy Scout and we went up for a scout skiing day there.. I had been acustom to skiing only at Snowbasin where I had been learning to ski for the past few years, all normal FGD and FGT lifts back then.. None of this stuff like you find on Wildcat at Alta, and the original Collins Yan, and I am sure on a few of the other LE/Yannie's that were there at the time. It blew my mind to see the return line so high in the air above me as we went up the mountain! Quite impressive. Is it safe to say that Yan/LE was the manufacturer who most commonly did this? Another question - Can you download on those lifts that are set up like that?

[Peter]

We are talking about 3 different things here...
- Offset towers
- Half towers
- Towers with crossarms at 2 different heights

Some offset towers are also half towers.

[Lift Dinosaur]

I am most familiar with these 3 types of situations from a Yan perspective-
I believe that the half tower-unrestrained down hill cable situation is found when the lift is a Bottom Drive. Since the unloaded downhill cable is being 'pulled' by the bottom drive bullwheel it has higher tension than the 'pushed and loaded' uphill cable. Engineer figures out how to save costs by having less equipment and smaller foundations.
Towers with 2 different crossarm heights is a similar situation but usually near the Bottom Drive Terminal where the tensions are more closely even.
I never quite understood the offset tower- they were really a pain in the a** to work on a access was extremely awkward. Perhaps to give access/clearance for Groomers to muck out the guest pit?
As for the question of down loading- that is generally left up to the Area to determine.
Hope this helps- Dino

[SkiDaBird]

RibStaThiok, on 04 March 2015 - 06:42 PM, said:

Alta had/has a few of them. I remember the first time I skiied there when I was just a little fresh 12 year old Boy Scout and we went up for a scout skiing day there.. I had been acustom to skiing only at Snowbasin where I had been learning to ski for the past few years, all normal FGD and FGT lifts back then.. None of this stuff like you find on Wildcat at Alta, and the original Collins Yan, and I am sure on a few of the other LE/Yannie's that were there at the time. It blew my mind to see the return line so high in the air above me as we went up the mountain! Quite impressive. Is it safe to say that Yan/LE was the manufacturer who most commonly did this? Another question - Can you download on those lifts that are set up like that?

Lifties do it for fun, but no you are not supposed to download.

[Conrad]

On Jupiter at Park City, probably half the the towers are only for the uphill side. There are three different times the descending chairs separate and do there own thing. And yes, I have seen a liftie download this thing!


Photo source: from Remontees-Mecaniques: http://www.remontees...rtage-4970.html

[Allan]

We've got a Doppelmayr T-Bar with a half tower, bottom drive top tension.

Attached File(s)

•  IMG_0227.JPG.JPG (1.81MB)
  Number of downloads: 65

[DonaldMReif]

Big Red at Whistler has a downhill-only tower.

[liftmech]

That one is due to the lift's profile-- theline there crosses a steep sidehill and the downhill carriers would hit the ground. The uphill (loaded) ones almost do as it is.

[SuperRat]

Loon Mountain Tote Road Quad. Cross Arms with different heights for ski under clearance (and groom under too) on a lift with loading and unloading in both directions

 Untitled-1.jpg (306.69K)
Number of downloads: 88

[NHskier13]

You also may want to note that this is commonly used for midstations:

[RibStaThiok]

Here's a funky but cool space saving design(I'm guessing that's the reason given what's below? It's not a mid-load/unload ramp) Moose Creek @ Jackson Hole

This post has been edited by RibStaThiok: 07 March 2015 - 09:26 AM