82 replies to this topic

[DonaldMReif]

snoloco, on 03 December 2013 - 04:38 PM, said:

I have noticed that there has been a trend in where the drive and tension are located based on the age of the lift. The oldest lifts were always bottom drive top tension. I think that they chose this because they did not know how to tension a drive terminal yet and they didn't know how to put a drive terminal at the top. Then they figured out that bottom tensioning was more efficient and made most lifts bottom drive bottom tension. Then they figured out how to make a top drive and the choice was the customer's as to where the drive and tension was. Another thing I have noticed is that tensioning on a lift is almost always at the bottom. The only times it won't is if the lift is a bottom drive and the design requires tensioning at the return, or if it is a top drive and tensioning is required at the drive. Am I correct about these things?

Age doesn't always factor in. There are some high speed quads built around the same time that are top drive bottom tension and others that are bottom drive top tension. For instance, at Keystone, the Peru Express and Montezuma Express lifts built in 1990 are top drive/bottom tension, and the Outback Express built a year later is a bottom drive/top tension.

[snoloco]

DonaldMReif, on 04 December 2013 - 01:08 PM, said:

Age doesn't always factor in. There are some high speed quads built around the same time that are top drive bottom tension and others that are bottom drive top tension. For instance, at Keystone, the Peru Express and Montezuma Express lifts built in 1990 are top drive/bottom tension, and the Outback Express built a year later is a bottom drive/top tension.

I was not talking about lifts from that age. I meant really old ones like from the 60's and 70's. The lifts where you unload and the chair continues overhead are almost always bottom drive top tension. Lifts with this configuration are usually very old. The ones where you unload directly at the bullwheel are almost always bottom drive bottom tension. The lifts with top tensioning almost always have a larger counterweight than those with bottom tensioning. This is because the counterweight has to hold up the entire line, not just take the slack out.

[Allan]

We've got an older Mueller (70s) that is mid-span unloading and is bottom drive-bottom tension, also have an old Thiokol (70s) and YAN (80) with bullwheel unloading that are top drive-bottom tension.

[Andy1962]

snoloco, on 03 December 2013 - 04:38 PM, said:

I have noticed that there has been a trend in where the drive and tension are located based on the age of the lift. ...(cut the text out). Am I correct about these things?

A couple other factors may go into the decision on drive location and tension location. Among them: amount of room at top or bottom of lift to put a terminal. If there is no room at the bottom because several lifts are already nearby, the return station might be down below and the drive / tension up top. Or noise: the customers desire to keep drive terminal away from a quiet scenic chalet. Or reverse mountain: parking is at the top of the "mountain" the ski runs run down into a valley. In this case the drive terminal might be up top for ease of electrical feed to the drive. As you can see the lift builders look at lots of factors in the decisions on drive terminal and return terminal locations that the average skier may not notice. Probaly lots more factors to consider. These are just a few.

This post has been edited by Andy1962: 05 December 2013 - 03:12 PM

[Peter Pitcher]

The oldest chairlifts were built at Sun Valley in the thirties. These were designed by Bob Heron and built by American Steel and Wire. These were all Top drive, bottom tension. This arrangement makes the most sense for a primitive design. The weight of the chairs and rope are pulling down on the tension terminal allowing the counterweight to be much smaller. The main disadvantage was that the guts of the equipment were at the top and if you were at the bottom and the lift wouldn't start, you had to go to the top which often meant a hike. There were no snowmobiles or snow cats. Bottom drive top tension lifts first appeared as rope tows and surface lifts but by the early sixties Poma was building chairlifts this way. The advantages were that you didn't have to run the power to the top of the mountain and when the lift wouldn't start you were right there. The disadvantage was that you generally needed a larger rope, therefore a larger rope gauge and a bigger gearbox i.e. more expensive. Bottom tension and drives give you the benefits of the bottom drive and the bottom tension. Mueller might have been the first to build these in the early sixties but there may have been others.

[DonaldMReif]

snoloco, on 04 December 2013 - 05:35 PM, said:

I was not talking about lifts from that age. I meant really old ones like from the 60's and 70's. The lifts where you unload and the chair continues overhead are almost always bottom drive top tension. Lifts with this configuration are usually very old. The ones where you unload directly at the bullwheel are almost always bottom drive bottom tension. The lifts with top tensioning almost always have a larger counterweight than those with bottom tensioning. This is because the counterweight has to hold up the entire line, not just take the slack out.

Talking about it that way, I realize I know some Riblets that are like that: Lift 5 and Lift A at Breckenridge, Twister at Crested Butte, and Looking Glass at Winter Park.

[snoloco]

I have noticed that some mountains have many more top drives than bottom drives or vice versa.

Mount Snow, VT is all top drive, bottom tension except for the Season's Double which is bottom drive, bottom tension.

At Killington, VT, all the fixed grips are top drive, bottom tension, except for the Snowshed Doubles which are bottom drive, bottom tension. All of the gondola's are top drive, bottom tension. However, their high speed quads are all bottom drive, top tension except for the Skye Peak Express which is top drive, bottom tension.

At Mountain Creek, NJ all the fixed grips are bottom drive, bottom tension except for the Granite Peak Quad which is top drive bottom tension. All the detachables are top drive, bottom tension.

Does anyone know what causes these trends?

[Lift Dinosaur]

90% of the time it is where they have 480V power available.
Dino

[SkiDaBird]

snoloco, on 21 April 2014 - 12:57 PM, said:

I have noticed that some mountains have many more top drives than bottom drives or vice versa.

Mount Snow, VT is all top drive, bottom tension except for the Season's Double which is bottom drive, bottom tension.

At Killington, VT, all the fixed grips are top drive, bottom tension, except for the Snowshed Doubles which are bottom drive, bottom tension. All of the gondola's are top drive, bottom tension. However, their high speed quads are all bottom drive, top tension except for the Skye Peak Express which is top drive, bottom tension.

At Mountain Creek, NJ all the fixed grips are bottom drive, bottom tension except for the Granite Peak Quad which is top drive bottom tension. All the detachables are top drive, bottom tension.

Does anyone know what causes these trends?

I'm also assuming it is a parts issue. All of the similar models at any resort I'v been to have the same drive/tension unless there is a reason not to, like on Honeycomb where the standard CTEC bottom drive wouldn't fit on that track.

[2milehi]

Lift Dinosaur, on 21 April 2014 - 01:56 PM, said:

90% of the time it is where they have 480V power available.
Dino

Not just 480V, but the ability to deliver a megawatt of electrical power and with minimal voltage drop.

[Nate214]

snoloco, on 21 April 2014 - 12:57 PM, said:

I have noticed that some mountains have many more top drives than bottom drives or vice versa.

Mount Snow, VT is all top drive, bottom tension except for the Season's Double which is bottom drive, bottom tension.

At Killington, VT, all the fixed grips are top drive, bottom tension, except for the Snowshed Doubles which are bottom drive, bottom tension. All of the gondola's are top drive, bottom tension. However, their high speed quads are all bottom drive, top tension except for the Skye Peak Express which is top drive, bottom tension.

At Mountain Creek, NJ all the fixed grips are bottom drive, bottom tension except for the Granite Peak Quad which is top drive bottom tension. All the detachables are top drive, bottom tension.

Does anyone know what causes these trends?

Efficiency a bottom tension does not have to work as hard as a top tension. A top bullwheel has more pressure than a bottom bullwheel so a top drive has better friction on the bullwheel with less tension work. It's better to pull than push. Sometimes it's the availability of power like mentioned earlier here but a top drive bottom tension is the most efficient setup. Although one can appreciate the Poma alpha terminal everything in one location and a fixed return.

[ceo]

Then there's the old Sugarloaf gondola which was middle-drive, top- and bottom-tension. :-) (It operated as two separate lifts with the drives in the midstation.)

[snoloco]

Whiteface, Gore, and Belleayre, NY are all state run mountains under the Olympic Regional Development Authority. Their lifts were installed as cheaply as possible since ORDA also has to fund the Olympic sites from the Lake Placid Olympics in 1980 and doesn't have much extra money. Mostly bottom drive (only 5 top drives in the entire chain), used instead of new, fixed grip instead of detachable even when the lift is long enough, and fixed lifts instead of replacing them.

[snoloco]

Okemo's Sunburst Six which replaced the Northstar Express is going to be a top drive. Northstar was a bottom drive, so they changed the drive configuration on this replacement. It seems like more often than not, when a lift is replaced, the drive configuration is the same on the new as the old, but I guess that isn't the case here.

[LuvPow]

snoloco, on 23 October 2014 - 11:33 AM, said:

Okemo's Sunburst Six which replaced the Northstar Express is going to be a top drive. Northstar was a bottom drive, so they changed the drive configuration on this replacement. It seems like more often than not, when a lift is replaced, the drive configuration is the same on the new as the old, but I guess that isn't the case here.

It is cheaper to have a top drive for a lot of reasons.... less concrete in foundations, smaller diameter rope.. in most instances.

[JSteigs]

LuvPow, on 23 October 2014 - 07:03 PM, said:

It is cheaper to have a top drive for a lot of reasons.... less concrete in foundations, smaller diameter rope.. in most instances.

Are you saying that because of higher tension needed for a bottom drive, the tower foundations will need to be larger? Same with rope Diameter?

[liftmech]

Not necessarily tower footings, but definitely terminals. Need more concrete in the ground to hold the extra tension.

[LuvPow]

JSteigs, on 24 October 2014 - 02:51 PM, said:

Are you saying that because of higher tension needed for a bottom drive, the tower foundations will need to be larger? Same with rope Diameter?

LIke Liftmech says... all big lifts should be a top drive. friction is directly related to tension, the more pull the more friction and a top drive is more efficient. The weight of the cable helps to pull on the bullwheel, gives you additional friction. The Stratton lift going in is a bottom drive, I believe the bottom is 65 tons.. bigger foundations, pylons.. on and on, that gets more expensive. It depends a lot of vertical rise..there is a formula for friction & tension Its all about the tension on the cable. The short answer with my experience anyway...

[DonaldMReif]

I heard somewhere else that whether a lift is top drive or bottom drive is also more or less relevant to which end is closer to a power source. I mean, look at Peak 6: the Zendo Chair is a top drive fixed grip quad because it doesn't cost much to run utility lines to the top of that lift, while the Kensho SuperChair operates as a bottom-drive high speed six pack because the budget would have probably been a lot larger if they had to run utility lines up to 12,302 feet. In fact, many of the lifts that service high alpine terrain that I've seen have bottom drive for that very reason. I think the only Loveland lift that even has top drive is the beginner lift #7. At least, that's what I heard.

[LuvPow]

DonaldMReif, on 25 October 2014 - 02:21 PM, said:

I heard somewhere else that whether a lift is top drive or bottom drive is also more or less relevant to which end is closer to a power source. I mean, look at Peak 6: the Zendo Chair is a top drive fixed grip quad because it doesn't cost much to run utility lines to the top of that lift, while the Kensho SuperChair operates as a bottom-drive high speed six pack because the budget would have probably been a lot larger if they had to run utility lines up to 12,302 feet. In fact, many of the lifts that service high alpine terrain that I've seen have bottom drive for that very reason. I think the only Loveland lift that even has top drive is the beginner lift #7. At least, that's what I heard.

well yeah, if you can't get power to the top it pretty much takes care of that.. its not an impossibility to have a bottom drive at all.. its just engineering and cost.