Lift Towers Impacted by Sun's Heat?

TomWhite

Deer Valley's X post (1st below) caught my attention. Then Instagram simply showed them painting a tower dark green. Then they mention white paint to prevent heating. So, it's not galvanized vs. steel but heat absorbing (unpainted) surfaces that is the point. I think we in the east want surfaces to absorb the sun's heat. Are they concerned about equipment being warped by the sun's heat?

X
The one lift at @Deer_Valley with galvanized towers no longer has galvanized towers.
instagram
The Deer Valley Lift Maintenance team painted the Burns Express chairlift this week. You may notice the base of the top tower was painted white. This is to help prevent the sun from heating the tower as it is more exposed than the others.

lotsoskiing

I am sure that's the reason.

I'd say Lee Summit was impacted by sun heating up atmosphere and producing crazy flooding. The pictures on LifBlog are incredible.

LiftGuy

The phenomenon is called ‘sun pull’, but it’s actually ‘sun push’. Overnight, the entire tower tube cools to a low temperature. When the sun comes up the side of the tower facing East is heated by the sun, causing the steel on that side to expand while the other side remains contracted. A 40’ tower can be moved as much as 6-8” at the top, and it’s exponential in 10’ increments. For a tower in a long span with large sheave assemblies, this may not be a problem. For break over towers at the top of a detachable lift this can cause significant cable deflection and misalignment on both the arrival and departure sides of the terminal, which is a bad thing. That is why you see many breakover towers on detachable painted white, with metal heat shields (air gaps), or white sleeves attached to prevent this deflection.
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TomWhite

Wow, I had no idea. Thanks.

obienick

Here’s a pic of the top of the gondola at Bretton Woods with the sun shields on the break over towered. https://skiliftblog.files.wordpress.com/2019/10/img_5142.jpg

The taller towers at the crossover don’t have the sun shields as they are not near the terminal.

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Here’s the break over towers on the Summit Express at Pico. Tops are painted a different color for the same reason. In this case lighter colors do not absorb as much heat as darker colors (the albedo effect). https://skiliftblog.files.wordpress.com/2018/10/img_37901.jpg