28 replies to this topic

[skierdude9450]

I see. So if the cabins are fully loaded, they need more support on the downhill side than if they were fully loaded on the uphill side, and if they're not loaded, it doesn't make much difference. And yes, to eliminate all doubt, I was talking about the Bridger Gondola at JH; I didn't know that there was another one.

[Tramway Guy]

It usually only happen with lifts driven from the lower station. A tower near the bottom will have much more tension on the downgoing side, consequently, there will be much more load on a tower from the tension effects acting on the wrap angle than the upgoing rope. And you have to allow for a cabin or two fully loaded coming over that tower combined with a fully loaded line going uphill at the same time. So, yes it is very likely to happen. It is much more likely with a gondola than a chair, but it can happen there also.

[skierdude9450]

After coming back from JHMR for a second time, I thought about this again. I'm still a little confused on this. It just doesn't make much sense to have a 6S/8S tower considering it's top drive, and the towers in question are not all near the bottom. First, it is highly unlikely that there would be a full downhill side and empty uphill side. Yes, it does take downloaders quite frequently, but not anywhere the number of people uphill.

This time I have pictures to show you:

Tower 4:
 P3281136.JPG (1.4MB)
Number of downloads: 67

Tower 9:
 P3281146.JPG (1.39MB)
Number of downloads: 51

[skierdude9450]

Tower 12:

Attached File(s)

•  P3281151.JPG (1.45MB)
  Number of downloads: 25

[tram mechanic]

skierdude9450, on Apr 6 2008, 08:52 PM, said:

After coming back from JHMR for a second time, I thought about this again. I'm still a little confused on this. It just doesn't make much sense to have a 6S/8S tower considering it's top drive, and the towers in question are not all near the bottom. First, it is highly unlikely that there would be a full downhill side and empty uphill side. Yes, it does take downloaders quite frequently, but not anywhere the number of people uphill.

This time I have pictures to show you:

Tower 4:
P3281136.JPG

Tower 9:
P3281146.JPG

though others can speak with more authority, there are times that this line can be loaded heavily on the downhill side. An event disperses at the top restaurant and hundreds of people leave with no one coming uphill.

[lastchair_44]

skierdude9450, on Apr 6 2008, 07:52 PM, said:

After coming back from JHMR for a second time, I thought about this again. I'm still a little confused on this. It just doesn't make much sense to have a 6S/8S tower considering it's top drive, and the towers in question are not all near the bottom. First, it is highly unlikely that there would be a full downhill side and empty uphill side. Yes, it does take downloaders quite frequently, but not anywhere the number of people uphill.

This time I have pictures to show you:

Are you aware we park cabins at night? And as Tram Mechanic stated, after 8:15 pm during night restaurant operations, there is no uphill traffic and only downhill traffic.


Edit 1- Tower four is also getting combo assembly installed within the next two weeks because it is so lightly loaded (hence less sheaves) that the rope tends to wander in pulse mode (four groups of five cabins). Tower 21 is also getting one, and maybe one other.

[skilift engineer]

The reason for more sheaves on the downhill side is due to radial acceleration. The downhill side has less tension therefore more sag and larger break over angles. The shape of a sheave train under load can be modeled as an arc. The more break over the smaller the radius of that arc and therefore a higher radial acceleration. The simplest way to decrease this acceleration is to add more sheaves. This makes the arc longer and increases the arc radius therefore less radial acceleration.

[lastchair_44]

Great explanation! Thanks!

[Peter]

That makes sense now, thanks for your insight!