62 replies to this topic

[KZ]

Here is a 16 sheave combination assembly

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•  combinedassembly.jpg (89.24K)
  Number of downloads: 25

[liftmech]

Doppelmayr's 8H8D addembly- looks very heavy!

Here is Riblet's lone 16-sheave tower (T-1 on Baker's C-8 quad)- with the opposing sheaves it comes to 24 on a side.

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•  Tower16D.gif (15.93K)
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[KZ]

Quite impressive for one tower.

[floridaskier]

DV's Silver Lake lift has a 16-sheave depression tower for the last tower into the end terminal. I've always wondered why, because this section is not at all steep

[liftmech]

Steepness doesn't always factor into the design- perhaps it's there to ease the transition out of the terminal and onto the first support tower. Many manufacturers would max out the design load on their sheaves when they built depression towers resulting in bumpier-than-necessary chair passage and decreased life on the sheave liners. That's why you see two and three towers at the bottom of many Riblets- they could use fewer sheaves per tower but still achieve the same effect.

[floridaskier]

Anybody have a picture of a CTEC compression sheave with 4 on the bottom and two on top?

[crazyskier91]

Anyone know why riblet always has in thier sheaves 1 on top and two on the bottom or vice versa and always in the same stlye? :help:

[SkiBachelor]

Quote

Riblet used only four sheaves per tower to allow for steeper tower angles. Tony Sowder (Doug's father) had a design philosophy wherein the sheave angle relative to the tower tube was as close to 90 degrees as possible, so he didn't want a great deal of weight up on the cap. As Riblet progressed to building triples and then quads, it became necessary to build towers with eight sheaves due to increased loads. (I was told by Doug that it would be not impossible, but difficult to build a six-sheave Riblet assembly.) If you ride Riblets a lot, you'll notice that the only eight-sheave assemblies are the newer rectangle-box ones rather than the older squashed-tube or the really old triangular box. A clarification- I refer to the number of support or depression sheaves on a tower, not the total including combo sheaves. There are some Riblet assemblies with a total of twelve sheaves, but that includes four combo sheaves. Tower 1 on Baker's C-8 has a combo with 16 depression and 8 support- the most I've seen on any lift.

It was either Ryan B or Liftmech that posted this a while back in another post, so here it is.

Ryan or John, whoever wrote this, please let me know, because I will be posting this on the site soon. ;)

[Bill]

That was Liftmech, he was employed at Baker.

[floridaskier]

Why did Riblet want the towers so steeply angled? Doesn't that put some extra stress on the tower foundation by having the think sticking out of the ground at a 45-degree angle?
Even on flat sections of Riblet lifts (and Doppelmayrs too for that matter) they angle the towers so they about perpendicular to the line. Is it worth it for a flat section? And then sone manufacturers, like CTEC, make every single tower perfectly vertical even on the very steepest sections (i.e. Empire Express at DV)

[SkiBachelor]

A few months ago, Ryan B posted a thread about tower placement. In that thread, he drew diagrams of towers and how the tower foundations looked. I have this info on my computer and I might post it later tonight if I have time. But the foundations arn't how you think. For angled towers, the foundation is angled, but then it goes straight down, so it won't fall over.

BTW, Garaventa CTEC did built angled towers on a few of its lifts. For example, the Snake Creek Express at Brighton, UT. The very last tower is angled.

[Kelly]

Ski Bachelor - credit should go to liftmech. To add to his post I belive Riblet got hit pretty hard on a code addition in the early 80s. "One sheave per degree of angle change". Riblet did have a large artistic design license with this issue.
Four sheave design per tower was self governing. He needed bigger components to allow for larger angles. Design did evolve later to include larger angles and loads.
Also one degree per sheave has changed as sheaves have gotten larger.
In wire rope industry (which ski industry is a part of) there is a correlation between sheave diameter and suggested degree of maximum angle change.

floridaskier-
Actually load force is perpendicular to the haulrope.
Riblets "lighter design" dictates tower must be perpendicular to haul rope. This also includes sheave assemblies and cross arms.
"Beefier" designs have more latitude with placement.
It should be noted that both types of design are well above any structural failure. Also both types have to resist deflection as the first criteria in their design. The only way Riblet can do this by angled tower placement.
Here are some titles of a few posts in Tech section that cover your question in more detail – start on page 2.
Design Methods…
Riblet Tower Alignment-
Poma Hsl Sheave Train-

Images Section
Odd YAN…

Ryan B

[liftmech]

floridaskier, on Apr 18 2004, 04:46 PM, said:

Why did Riblet want the towers so steeply angled? Doesn't that put some extra stress on the tower foundation by having the think sticking out of the ground at a 45-degree angle?

That's part of the reason you'll only see four sheaves on a tower on older Riblets- the lighter tower cap weight made it easier to 'hang' the tower out there at steep angles. I've started a new thread on towers and tower loading in the tech section for further discussion.

[liftmech]

More styles of combo assemblies:
Poma's 2-4-2 (may also be seen upside-down)

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•  2_4_2.jpg (226.55K)
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[liftmech]

...paging hardware... are you missing a wheelbarrow tyre? One of Yan's more interesting designs.

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•  spare_tyre.jpg (84.35K)
  Number of downloads: 33

[SkiBachelor]

What is that tire used for anyway? I have always wondered since the Red Chair at Mt. Bachelor has two.

[Dr Frankenstein]

Müller have used tyres too. (Chaise du ciel @ Orford)

[floridaskier]

Mayflower at DV (Yan) has a few of those. I've also wondered what the heck those are for, because they all seem to have a pretty positive load, and all it does is squeak. This lift also has regular Yan compression assemblies

[Allan]

The only thing I could see them being used for is to prevent rope lift-off when there are no chairs on the line. Other than that I don't know. It really does look like a wheelbarrow tire :)

[ODDfreakPERSON]

wow, never seen one of those before