47 replies to this topic

[Powdr]

Skier, on Mar 7 2006, 09:44 PM, said:

This planetary was opened up last summer and non destructive testing (NDT) was done on the parts inside. There were no problems and that makes this failure even more perplexing.

What kind of testing was performed? NDT can mean many things. XRD is probably the best, but likely can not be performed in the field, so i'm guessing that it wasn't used. The tests therefore might not have seen flaws/cracks deep within the gearbox. Failure analysis of the part(s) will tell whether the part failed due to overloading or flaws introduced during the manufacturing process. Either way, the manufacturer bears repsonsibility unless specific lifecycle limits were given on the new equipment. Whatever the outcome, I can't see how PCMR (or any other owner of that same lift/gearbox) would not have to retrofit over the summer. Depending on the number of lifts with that configuration, there could be a critical shortage of those part this summer. I would make sure I was 1st in line, if I was PCMR.

Powdr

[lastchair_44]

usually an ultrasound or ultrasonic testing is perfromed on gearbox/hub components. Also, I think CTEC is paying for the majority of the project.

[floridaskier]

Some pictures of the repairs:





On an unrelated note, the Silver King run and Ski Team lift:



The PCMR blog says that:
"When Bonanza went down four weeks ago we made the decision to retrofit PayDay lift with a larger gear box in April, when the season ends. There are now discussions to retrofit the other three six-packs with the larger gear boxes to prevent this from occurruing in the future."

I really like this PCMR blog, especially when they're talking about the lifts. Read more about Payday:
http://parkcity.typepad.com/park_city_moun..._the_deal_.html

[Peter]

I like how they are actually being up front with the problem and the solution. Snowbird had Gad II down for a month and called it ''routine maintenance.'' Sunshine Village also used "routine maintenance" when the cabins fell off!

[Peter]

PCMR linked this topic to their blog. The latest...

A snowy Thursday!
Payday Lift re-opened yesterday morning at 9:00am as planned, and we are working with our lift manufacturer and their vendor (s) to determine exactly what replacement parts are needed for the McConkey's Lift. We should know in the next day or so the status of these repairs and if all goes well McConkey's Lift may be back in operation as soon as next weekend! In the meantime, we are still keeping access to all areas served by McConkey's open via the South Jupiter Peak traverse, pending snow safety. Also, it's snowing, so I'm going to try to get out to do some 'product sampling' and hopefully have some photos to post shortly!

In response to Scott K's Comments:
While the Payday lift evac last Sunday was in progress, we did close the McConkey's and Jupiter areas of our resort in order to bring additional manpower in and expedite the process as much as possible. These areas were open again the next day and we have had all of our skiable terrain open (again, pending snow safety) since Sunday. If our lift manufacturer had informed us that we should have a spare gearbox on hand we would have done so, but they didn't, and therefore we unfortunately had to resort to cannibalizing our own lift to get Payday back in service. An informative discussion on this issue can be read at http://www.skilifts.org/nwsforum/index.php...topic=3773&st=0.

Posted by EricH on March 09, 2006 at 08:53 AM | Permalink | Comments (0) | TrackBack (0)

[floridaskier]

Nice, they mentioned us in their blog
Also interesting, the sentence before:
"If our lift manufacturer had informed us that we should have a spare gearbox on hand we would have done so, but they didn't, and therefore we unfortunately had to resort to cannibalizing our own lift to get Payday back in service."

Sounds like a cheap shot at CTEC there, so maybe there is some bad blood between PCMR and CTEC after three major problems in two years

[Peter]

Keep in mind that CTEC now includes Doppelmayr, and there are virtually NO Leitner-Poma lifts in Utah. It seems unlikely that they would switch manufacturers with their close proximity to DoppelmayrCTEC.

[Powdr]

OK, now that PCMR has averted that PR crisis, does it not point out the dire need to have an additional high capacity lift up the mountain from the base area? If either Payday or Bonanza go down, PCMR is left with some very poor options (1st Time - Ski Team - Silverload or Eagle - Con - Silverload). Either route increases time to get up the mountain and greatly increases guest agrivation, Espicially since a long line or bottleneck will be encountered somewhere along the way. So, since I never shy away from giving my opinion, here are the three options I see as a vital alternative to get people up the mountain:

- Gondi from the Base to the Summit area in a straight shot. Then add (or streamline) a few more top to bottom ski routes to encourage looping on that lift. This addresses PCMR's other short fall; not enough long runs.

- Gondi from Base to Summit area with a mid station on top of Ski Team ridge. This is my favorite option, as it re-emphasises the under used Ski Team runs.

- HSQ replacing Ski Team, but extend it down to where it used to start. Addresses the uphill issues, but doesn't do anything for strecthing out the skiing.

Powdr

This post has been edited by Powdr: 10 March 2006 - 08:59 AM

[floridaskier]

I like the idea of replacing Ski Team with a HSQ, but in a different line so that it ends where Crescent used to end. That would serve a few more runs that you can only get to from the Payday-Bonanza combination. Also, it would start down at the bottom where it used to (actually, it started in a random spot just above the base, so you had to hike a little bit to get to it). They could use that extra capacity on most normal days, and the whole Ski Team area is mostly forgotten. King Con and Silverlode can have big lines on a good day

Is the gondola from the hotel going in for sure? That would add a lot of capacity from the base, but I think Ski Team should be replaced anyway

[Aussierob]

I must admit to not being too familliar with CTEC's gearbox setup, but it seems they have an extra planetary set mounted on the bullwheel that does the final reduction, and this is the troublesome component. There are huge torque loads at this point in the drivetrain, so anything not sufficiently specced will tend to fail. This could be due to pricing demands by the ski area at purchase time. The ski area wants the cheapest lift and grinds the manufacturers on their quotes. The manufacturers can save significant money if they can get away with a gearbox that is just big enough, rather than one that has some extra margin. It's a case of pay me now or pay me later. It would seem maybe the planetary's wern't quite big enough. All our Doppelmayrs and Pomas have the reduction stages in the main gearbox, which seems to be a simpler setup to me. They also give no trouble.

[Outback]

Aussierob, on Mar 10 2006, 02:44 PM, said:

I must admit to not being too familliar with CTEC's gearbox setup, but it seems they have an extra planetary set mounted on the bullwheel that does the final reduction, and this is the troublesome component. There are huge torque loads at this point in the drivetrain, so anything not sufficiently specced will tend to fail. This could be due to pricing demands by the ski area at purchase time. The ski area wants the cheapest lift and grinds the manufacturers on their quotes. The manufacturers can save significant money if they can get away with a gearbox that is just big enough, rather than one that has some extra margin. It's a case of pay me now or pay me later. It would seem maybe the planetary's wern't quite big enough. All our Doppelmayrs and Pomas have the reduction stages in the main gearbox, which seems to be a simpler setup to me. They also give no trouble.

Thats quite an assumption of how those planetary's work with budgets as the final drive!
Secondary planetary's in bullwheels have been around for awhile to achieve more torque than the gearbox with a shaft stickin' out of da bottom concept.
Not necessarily the item where margins are cut on lift proposals.

[Kicking Horse]

So are you saying what Rob said is wrong? If so what do they cut on lift Proposals?

[floridaskier]

The Bonanza repairs in February

PCMR has done a great job of handling this. I hope they get McConkey's back up soon

[Aussierob]

Gearboxes are the single most expensive component on a ski lift. If you can get away with using a size smaller gearbox, the savings can be significant. Its one place the manufacturers look if the ski area starts grinding down the price. I was at the Canada West Ski Area conference a few years ago and gearbox life and rebuild inteval was discussed. The concensus was that if you go smaller on the box to cut costs you will have more frequent rebuild intervals and potentially more problems. Most companies have separate capital and operating budgets and tend to prefer higher operating costs to get lower capital cost. Go figure. As for the design in general, I assume a smaller box and planetary final drive is cheaper than a bigger gearbox and no planetary. I can't think of any other reason to design it that way (note: I'm not an engineer)

[liftmech]

Someone else mentioned it in the thread, but I was under the impression that the CTEC sixpacks used the same D11 hub as the quads. I would think they would want a larger hub for the larger loads encountered on a sixpack. $0.02

[lastchair_44]

liftmech, on Mar 12 2006, 01:43 PM, said:

Someone else mentioned it in the thread, but I was under the impression that the CTEC sixpacks used the same D11 hub as the quads. I would think they would want a larger hub for the larger loads encountered on a sixpack. $0.02

no...it's the kissling hub, and yes their setup is the same as the HSQ's of that vintage. They're going to retro to a cat hub this summer...maybe a bigger box?

[Kelly]

Reasons bullwheel hub planetary's are used is that they offer an inherent stiffness to the bullwheel and the coupling system between the bullwheel and gearbox. Also with the multi stages of larger horsepower designs it’s a good place to add a space for the last stage.
If my memory serves me well I believe Riblet started using bullwheel hub planetary gearboxes in the early 70's. These were Caterpillar final drives often seen in loaders and large road graders just tipped 90 degrees for a ski lift application.
Service factors on any type of component are a big factor in cost – pretty much proportional – but as Outback implies the benefits of cost cutting of this one component don’t out-way the consequences of its failure – historical records show that this is the last component to fail on a ski lift not the first.
Acceleration/Deceleration torque loads are a major factor in gearbox design and what's interesting concerning this topic of gearbox failures is that is the speed of acceleration can be field adjusted or misadjusted.
Of course let's not forget metallurgy, casting and production manufacturing, all come with areas that humans can make little mistakes that have big consequences.
My guess is that the acceleration load parameters are being closely investigated.

Attachment shows a mechanic raising the "guts" of a planetary hub into position with all-thread. An alternate method is to raise the component with a jack and use the all-thread as a backup. The red arrow shows the planet hub or carrier, green arrow shows planet gear – sun gear can not be seen as it is inside planet carrier. Blue arrow shows supervisor wearing white fleece.

Color cross-section shows a similar planetary gear system – the planet carrier hub has been omitted for clarity.

Attached File(s)

•  bonanza_gearbox_for_web.jpg (112.17K)
  Number of downloads: 29
•  planetary_color_cross_secti.jpg (35.69K)
  Number of downloads: 20

[towertop]

What does Tom Kerr say?

[SkiBachelor]

Here's a write up in the Salt Lake Tribune about the incident at Park City Mountain Resort. I guess all the gearboxes in the in the six-packs are going to be replaced by Caterpillar ones this summer. However, I find that kind of strange though since I don't recall Caterpillar gearboxes ever being used in lifts before.

http://www.sltrib.com/utah/ci_3583904

[Lift Dinosaur]

[ However, I find that kind of strange though since I don't recall Caterpillar gearboxes ever being used in lifts before.

The "Cat gearbox" is actually a planetary gearbox, as discussed by RyanB and liftmech above, that is used as the final reduction drive in the line. A smaller, right angle gearbox is placed on top of it for the primary reduction stage. The bullwheel is mounted to the Cat planetary.
In a stand alone planetary box, such as the Poma-Kissling, the final reduction stage is in the bottom of the gearbox with an output shaft, which turns the bullwheel.
Heron and Riblet used "Cat Hubs" as final reduction back in the early 70's.
Hope this helps.