17 replies to this topic

[GasTOPS]

Hello Fellow Members,

We are evaluating the potential benefits of applying an online condition monitoring sensor for ski lift drivetrain gearboxes. Technically we have a well proven solution consisting of an oil debris monitor that installs in the oil lubrication system downstream of the gearbox scavenge and upstream of the oil filter. An increase in wear debris particle counts indicates bearing and/or gear distress/damage at the earliest possible stage (i.e. as soon as a bearing/gear surface spall appears). Based on several years of experience using these sensors for monitoring of wind turbine gearboxes we believe that ski lift operators will benefit from these sensors by 1) having confidence in the condition of their gearboxes (or not!) and 2) being able to continuously monitor the condition/damage progression of their gearboxes such that the usable operating life of the machine can be optimized, e.g. to get through the ski season avoiding lost operating time and save money/improve maintenance logistics. A possible third benefit would be the prevention of a lift stoppage that necessittates skier rescue, although our research has revealed just one report of such an incident due to a gearbox failure.

Note that this is not an oil condition sensor (i.e. not affected by normal/benign wear or oil contaminants), this is a machine condition sensor that detects the presence of abnormal wear debris from bearing and gear surface damage accounting for > 80% of gearbox mechanical failures.

Would this benefit your operations?

Are gearbox bearing and gear failures a big concern?

What are the risks and costs associated with a sudden gearbox failure on a ski lift?

Thanks.

[Kicking Horse]

I'm just a lift operator however I do have some questions about this.

What would the costs be to install such a item on a lift? (if you have looked into this)

Will it shut the lift down if it detects anything? (If so I could see false postives)

Gearbox failure is a huge concern for any lift in the world. As it's a single souce of failure.

[rniemi]

GasTOPS, on 07 January 2010 - 11:53 AM, said:

A possible third benefit would be the prevention of a lift stoppage that necessittates skier rescue, although our research has revealed just one report of such an incident due to a gearbox failure.

I'd say there's been a lot more than just one gearbox failure incident that has resulted in evacuation. At least one (well-publicized) gearbox failure has already occurred this season. Out of curiosity, which was the one incident your research turned up?

-Ryan

[mthornton]

The below previous post from the technical section, prior to any recent gearbox accident, where there is additional discussion. These chip detectors are effective, available & cheap. But every gearbox is different, as is the diligence from the maintenance staff to other early warning signs (visual gear inspections, temperatures & daily monitoring of feel & sound during daily checks).

Having conscientious, diligent & knowledgeable maintenance staff crawling all over these machines is defense #1. Chip-detection alarm is defense #2, and is only of value if it is attended to by #1. If you don't have #1, nothing will help.

That said, depending on the gearbox, chip-detectors may indeed be of some value.


===============================


Posted 17 November 2009 - 12:20 PM

Yesterday in the lunch-room we were chatting about chip-detectors used in helicopter & aircraft engines (& gearboxes).
http://www.chiefairc...ipDetector.html
http://www.tedecoind...om/electric.htm

Any experience with these?
Attached thumbnail(s)

• uploads/monthly_11_2009/post-1606-125848571299_thumb.jpg

This post has been edited by mthornton: 17 November 2009 - 12:21 PM

[Skiing#1]

I remember in about 2006 or 2007, Park City Ski Mountain's lift Payday gearbox went down and they pulled the gearbox from McConkey Lift and installed it on Payday Lift. I looked and found the information.

http://parkcity.type...y_lift_upd.html

PAYDAY LIFT UPDATE 3/5

Our Payday Lift went down with mechanical problems around mid-morning today. The problem has been diagnosed and our lift maintenance team is already hard at work, making repairs. Unlike Bonanza, which required a part to be shipped from Switzerland, repairs for Payday will come from a closer source...our own McConkey's Lift. If all goes as planned, we should have Payday up and running by Wednesday morning.

Unfortunately McConkey's will have to wait for parts from overseas, and we will provide an update on that lift's re-opening as soon as we know more. Some of you hikers, who remember the old days, may actually enjoy this. McConkey's terrain will still be accessible via the Jupiter Lift and a little hiking. More new snow is expected this week.

We know this will affect how a lot of you access the mountain and we have modified our grooming schedule to make sure your day is still an enjoyable, fulfilling experience. Accessing the upper part of the mountain can be accomplished one of two ways. Take First Time Lift to Ski Team Lift. Or, take Eagle Lift to King Con Lift. Both of these options will allow you to visit great terrain all around the mountain.

Posted by justin@pcski on March 05, 2006 at 04:17 PM | Permalink

http://parkcity.type..._the_deal_.html

What's the Deal with the Lifts?

Good news is PayDay is expected to open for business on Wednesday morning. As Justin stated in his previous blog we pulled the gear box from McConkey's to get PayDay up and operating as quickly as possible. Our lift maintenance team worked through the night to get PayDay's gear box out. This picture was taken at 8 am this morning. The gear box is an intricate piece of the 12,000 pound bull-wheel assembly shown.

As for McConkey's, we are in the process of ordering the parts needed to replace the broken ones in PayDay's gear box. We should know when we will receive the parts by tomorrow morning. In the meantime, the terrain serviced by McConkey's can be accessed via the South Traverse around Jupiter Peak, which is dependent on snow safety.

I'm sure all of you are just as befuddled as I am about how another lift could experience mechanical problems at Park City Mountain Resort. I have been on the phone all day with Jan Leonard, president of Doppelmayr CTEC, the manufacturer's of our six-passenger chairlifts. Of the 22 lifts that have this gear box installed, only the four at Park City Mountain Resort are six-passenger chairlifts, the others carry less of a load (ie, four-passenger chairlifts or less). He has assured us that they will do everything they can to resolve these issues. In an interview that we did together with the Park Record, he will be quoted as saying, "Park City Mountain Resort could have done nothing to prevent these lift failures. It is an engineering or materials problem within these gear boxes."

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.

Our lift maintenance team performs numerous tests on the gear boxes each summer. In fact this past summer they logged more than 18,000 hours in maintenance. These test show any indications of metal fatigue and cracks that can't be seen by the naked eye. Last summer the PayDay Lift passed with flying colors, so the recent breakdown is even more perplexing to us.

We will keep you updated as we find out more information. Make sure you check back here often to see the updated posts. It's dumping outside right now...the forecast is calling for up to a foot by storm's end. There should be a lot of great snow! See you on the mountain.

Posted by Kristap on March 06, 2006 at 05:55 PM | Permalink

This post has been edited by Skiing#1: 10 January 2010 - 04:41 PM

[GasTOPS]

Kicking Horse, on 08 January 2010 - 07:49 PM, said:

I'm just a lift operator however I do have some questions about this.

What would the costs be to install such a item on a lift? (if you have looked into this)

Typically one sensor would be needed, sized appropriately to monitor the full flow of the oil pump discharge. The sensor outputs a pulse for each detected particle. This pulse signal could be connected to the lift's control panel if a spare pulse counter input is available, otherwise an Alarm Module (with web server) is available for monitoring/alarming/local display. A 24 VDC power source is needed as are some fluid line fittings to install the sensor in the lube oil line. A one-off complete installation would cost about $7k.

Will it shut the lift down if it detects anything? (If so I could see false postives)

No, it should not be used for automatic shutdown. The advantage of this sensor is its ability to detect the damage as soon as it starts, and the ability to trend the particle counts versus time (in a cumulative manner) to indicate the severity of the damage as the gearbox continues to be operated. Therefore it fits with a pro-active condition-based maintenance program and allows operators/maintainers to avoid the very costly/disruptive unscheduled gearbox failures

Gearbox failure is a huge concern for any lift in the world. As it's a single souce of failure.

Thank you, good questions and feedback!

[GasTOPS]

rniemi, on 09 January 2010 - 06:32 AM, said:

I'd say there's been a lot more than just one gearbox failure incident that has resulted in evacuation. At least one (well-publicized) gearbox failure has already occurred this season. Out of curiosity, which was the one incident your research turned up?

-Ryan

That was at Mount Snow in Vermont in the 1980's that shutdown one of their main chairs during the peak Christmas season and due to a bearing failure in the gearbox. I've now found others including Devil's Head, WI last year with some unfortunate injuries after a roll-back incident due to lost braking when the gearbox failed?...not sure if that's plausible? What is the one that has occurred this season.

Another benefit for operators could be reduced insurance premiums for adding effective condition monitoring. Wind turbine operators are able to get reduced insurance rates by fitting oil debris monitoring sensors to their gearboxes, and that's just based on reducing the damage severity and minimizing maintenance costs and doesn't include reducing risk of injury to people!

Thanks for you feedback!

[GasTOPS]

I absolutely agree that pro-active maintenance is the best plan. There is a trade-off between having knowledge of the condition of the gearbox internals on a regular basis through internal inspections which are expensive, requiring specialists using expensive videoscopes, and in themselves do present a small risk of actually creating a problem (e.g. like the wind turbine that had to be shutdown for several weeks after a screw was dropped into the gearbox during an inspection!). The oil debris monitor is not a chip detector. Chip detectors capture particles on a magnet and trigger an alarm but are very much prone to false alarms. The effectiveness is also dependent on the placement as a chip detector is not efficient at capturing particles. They are also a reactive sensor because it takes a severe amount of damage to the components before they give an indication of damage, and based on many incidents in helicopter main rotor gearboxes, the indication doesn't come in time! Another problem that results in false alarms from chip detectors is that they capture ALL wear debris, including the very small particles (<100 microns) that normally are produced in a gearbox from normal/benign wear, especially a new gearbox during the break-in period. The on-line oil debris monitor does not capture particles, it counts them as they pass through the sensor on the way to the filter. And it only counts the particles that are larger (>200 microns) that are produced from the abnormal/destructive damage as soon as it begins. This is referred to as spalling/destructive pitting and occurs on roller bearing and gear contacting surfaces.

The idea is the continuous on-line monitoring of gearbox condition with the oil debris sensor is used in a condition-based maintenance plan
to trigger inspections and repairs but it should not completely replace the internal videoscope inspections.
Thanks for your feedback!

*Long quote removed from post by forum Administrator Kelly

[GasTOPS]

I remember in about 2006 or 2007, Park City Ski Mountain's lift Payday gearbox went down and they pulled the gearbox from McConkey Lift and installed it on Payday Lift. I looked and found the information.

http://parkcity.type...y_lift_upd.html

I have been on the phone all day with Jan Leonard, president of Doppelmayr CTEC, the manufacturer's of our six-passenger chairlifts. Of the 22 lifts that have this gear box installed, only the four at Park City Mountain Resort are six-passenger chairlifts, the others carry less of a load (ie, four-passenger chairlifts or less). He has assured us that they will do everything they can to resolve these issues. In an interview that we did together with the Park Record, he will be quoted as saying, "Park City Mountain Resort could have done nothing to prevent these lift failures. It is an engineering or materials problem within these gear boxes."


If the problem was due to a progressive damage to the bearings and or gears as is the case in >80% of gearbox failures, oil debris monitoring would have provided the indication of the initial damage and probably hundreds or thousands of operating hours before the forced stoppage occurred. There are many potential root causes of bearing or gear surface fatigue problems, including quality control problems such as incorrect material and/or heat treatment.

Thanks.

[floridaskier]

The same thing happened at Park City three times in those two years. to Bonanza and Silverlode too. Silverlode was first, in early 2005, followed by Bonanza and then Payday in the 2005-06 season. As I remember, all three times they pulled the gearbox and other components out of McConkey's and used them to repair the important lifts. For a while, the soffits on the undersides of all the six pack drive terminals at Park City were removed and you could see everything. The replacement soffits are different than the originals, and a lot more of the replacement machinery sticks out of the bottom now. They went ahead and replaced the Kissling gearboxes the next summer on all four six packs, as well as on King Con and First Time, both high speed quads that never had the problem. The new Caterpillar gearboxes have been reliable as far as I can see from an observant customer standpoint ever since.

I always thought it was stupid to build McConkey's as a six pack, since it hardly gets any traffic (they don't even set up a maze) but it saved their rear ends that year to be able to pull out replacement parts for the other three nearly identical six pack chairs. Payday, Bonanza, and Silverlode are the three most important lifts by far, even more so back then, and having them down for only a few days instead of weeks was a big help

[GasTOPS]

We're hearing that condition monitoring is not something that the ski lift industry is ready to embrace, with the possible exception of Intrawest and Vail. Run-to-failure without warning and no on-hand spare parts is, and will continue to be the way that most of the industry operates. Anyone care to comment?

[mthornton]

GasTOPS, on 14 January 2010 - 07:24 AM, said:

We're hearing that condition monitoring is not something that the ski lift industry is ready to embrace, with the possible exception of Intrawest and Vail. Run-to-failure without warning and no on-hand spare parts is, and will continue to be the way that most of the industry operates. Anyone care to comment?

Perhaps you are generalizing in a manner that will not help your cause. There has been & is considerable relavent discussion, but in the technical section of this forum, not the public section. This is also not the place for ads.

Most of the industry is extremely diligent in all aspects of maintaining their lifts, including the monitoring of their gearboxes. I work for an Intrawest company, and we will certainly not leap at any new $7k/per automatic oil monitoring device unless we are fully convinced it is required & beneficial above our present monitoring methods. If the lift manufacturers, or our safety authority mandate such devices, then we will use them. Please post a link to detailed technical information your device.

Resistance against automatic monitoring equipment is often based on concern over the displacement of traditional human monitoring. A good diligent lift mechanic knows the exact sound, feel & smell of each of his gearboxes, and that aspect cannot be automated. Oil-sample analysis is performed routinely, as are internal visual inspections.

Aircraft gearbox chip-detectors cost $300 ea, and although a very simple & inexpensive device, would certainly would have alarmed well ahead of the recent catastrophic gearbox failure at DH. Your device has to clearly provide superior value & function if you want the market to respond.

Automatic gearbox oil temperature monitoring w/alarms, is very common.

M

[GasTOPS]

Does anyone have more information about what caused this recent incident with a gondola in Germany?

A cable-car ski lift holding 43 people was stuck for more than two hours on the Brauneck mountain in southern Germany on Tuesday, when a probable mechanical failure caused the brakes to seize up.

Walkers and skiers, travelling up the mountain in the lift's 4-person pods, found themselves trapped dozens of metres over the ground in freezing temperatures for up to two-and-a-half hours, after the emergency brakes brought the system to a sudden halt.

Those lower down were able to be rescued by the fire brigade using ladders, and others clambered down using ropes. Helicopters were sent to free people trapped further up the mountain.

Some of the passengers simply strapped on their skis to reach the bottom of the mountain, while most were carried down by the rescue services.

None of the passengers, aged 10-66, was injured, and police said that nobody panicked.

The Brauneck lift, servicing a popular ski resort close to the Bavarian capital Munich, is around 2.5 kilometres long and carries people 800 metres up the mountain.

[GasTOPS]

Confirmation of the gearbox failure at Devil's Hill and the subsequent failure sequence:

http://www.chicagobr...obref=obnetwork

What are the ski lift safety authorities in the USA and Canada?

[Kelly]

To the viewers of this forum -
The topic originator is a representative from a Canadian company that is somewhat aligned with the maintenance side of the ropeway industry, one of its specialties, as he states is oil monitoring. Let’s be patient with this new member of the forum.
The topic title byline is now changed to reflect actual contents.
Here is an image of the company’s oil analysis page
 gastops 1.jpg (62.4K)
Number of downloads: 30
Here is an odd image (it takes up 30% of the total image space) of the front page – condition monitoring or expert lititgators?
 gastops 2.jpg (155.86K)
Number of downloads: 33

In response to the post referencing some replies as a classified ad I agree too many more vague references to the “product” and this topic will be shortened and moved to the classified section.

-Brauneck mountain
Please attach a link to the original media source – there is no outside reference so this post could be bogus. I think we “get it” the application of your product any other tie-in post to your product is unnecessary…however I will check on this incident and put any relevant information in the industry side – SORT members please post any relevant information in the industry forums – Thanks Kelly.
Industry forums link: http://www.skilifts....t=0

To gasTOPS:
Post # 14 …Confirmation of the gearbox failure at Devil's Hill
I would be a little hesitant in referencing a news headline as actual fact. This topic has been discussed at great length in the industry only forums (SORT has over 2000 at this time). I feel very comfortable saying the media has reported on the majority of the symptoms and very comfortable in saying the media failed with any sequence analysis - they missed by a mile or a kilometer in your case.

What are the ski lift safety authorities in the USA and Canada?
This is a pretty comprehensive link for that information
http://www.ropetech....ry_-_Links.html

gastops:
What is the specific cost breakdown for one of your monitoring units and can you give us any real-world data (charts etc.) on how you saved a gearbox (test stand or actively being used) from failure via conditioning monitoring?
Thanks
Kelly
Forum Administrator

[GasTOPS]

Kelly, on 14 January 2010 - 12:40 PM, said:

To the viewers of this forum -
The topic originator is a representative from a Canadian company that is somewhat aligned with the maintenance side of the ropeway industry, one of its specialties, as he states is oil monitoring. Just to clarify, the oil debris monitor (I use the generic name, there are now several similar products on the market that try to duplicate our MetalSCAN product) will detect metal particles carried in the oil from the damaged components inside the machine and it is not monitoring the condition (i.e. viscosity, etc.) of the oil itself. Oil condition monitoring or oil sampling is an entirely different technique that can indicate when it is time to change the oil but has limited ability to be an early indicator of component damage inside a gearbox.

Let's be patient with this new member of the forum. I'm sorry if my posts have had too much of a sales slant. My purpose is to gather information from the community on the feasibility/viability of introducing this new maintenance technique for gearboxes. I will try to answer questions referring to the generic technique of oil debris monitoring, and not specifically to a particular product

The topic title byline is now changed to reflect actual contents.
Here is an image of the company's oil analysis page
gastops 1.jpg
Here is an odd image (it takes up 30% of the total image space) of the front page – condition monitoring or expert lititgators?
gastops 2.jpg
Yes, we recently won a ruling against a group of former employees who usurped a part of our software business back in 1996...old news, should have been removed by now in my opinion...

In response to the post referencing some replies as a classified ad I agree too many more vague references to the "product" and this topic will be shortened and moved to the classified section.

-Brauneck mountain
Please attach a link to the original media source – there is no outside reference so this post could be bogus. I think we "get it" the application of your product any other tie-in post to your product is unnecessary…however I will check on this incident and put any relevant information in the industry side – SORT members please post any relevant information in the industry forums – Thanks Kelly.

Will do.
Industry forums link: http://www.skilifts....t=0&#entry67844

To gasTOPS:
Post # 14 …Confirmation of the gearbox failure at Devil's Hill
I would be a little hesitant in referencing a news headline as actual fact. This topic has been discussed at great length in the industry only forums (SORT has over 2000 at this time). I feel very comfortable saying the media has reported on the majority of the symptoms and very comfortable in saying the media failed with any sequence analysis - they missed by a mile or a kilometer in your case.

Thanks, I will look to SORT for further information. Confirmation was the wrong word, I should have said report.

What are the ski lift safety authorities in the USA and Canada?
This is a pretty comprehensive link for that information
http://www.ropetech....ry_-_Links.html

gastops:
What is the specific cost breakdown for one of your monitoring units and can you give us any real-world data (charts etc.) on how you saved a gearbox (test stand or actively being used) from failure via conditioning monitoring?

Our sensor sells for $3k to $4k, depending on the version. An optional Alarm Module is available for less than $2k. Assuming the Alarm Module would be needed, plus cabling and fluid line adapters, it comes out to around $7k (assuming one only).

Attached is a technical paper on the subject of the oil debris monitor applied to gearboxes in wind turbines. We expect the failure modes are the same so the real-world data presented is equally applicable to the ski lift gearbox.
Thanks
Kelly
Forum Administrator

Attached File(s)

•  7th World Wind Energy Conference.pdf (564.7K)
  Number of downloads: 16

[mthornton]

Thanks GasTOPS
The pdf article (7th World Wind) is good reading. Will be in touch re the MetalSCAN sensor.

We are a suspicious bunch aren't we.
MThornton, Panorama Mountain Village

[GasTOPS]

mthornton, on 14 January 2010 - 08:15 AM, said:

Perhaps you are generalizing in a manner that will not help your cause. There has been & is considerable relavent discussion, but in the technical section of this forum, not the public section. This is also not the place for ads.
I guess I have to admit that the wording I used was chosen to provoke responses...and I appreciate yours, thanks.

Most of the industry is extremely diligent in all aspects of maintaining their lifts, including the monitoring of their gearboxes. I work for an Intrawest company, and we will certainly not leap at any new $7k/per automatic oil monitoring device unless we are fully convinced it is required & beneficial above our present monitoring methods. If the lift manufacturers, or our safety authority mandate such devices, then we will use them. Please post a link to detailed technical information your device.
Being an avid skier myself and now riding chairs with my 3 and 5 year olds those are comforting words to hear!

I hope that the technical paper attached provides the detailed technical information that you need.

With regards to cost justification, it's a very easy analysis for the wind energy application because of their gearbox reliability problems and the known maintenance and lost production cost savings. The business case for ski lift operators will factor in some cost savings, possibly by allowing more condition-based maintenance and reducing costly reactive repairs (and maybe reduced insurance premiums?), but also the benefits of much higher confidence in machine condition and safety.

Resistance against automatic monitoring equipment is often based on concern over the displacement of traditional human monitoring. A good diligent lift mechanic knows the exact sound, feel & smell of each of his gearboxes, and that aspect cannot be automated. Oil-sample analysis is performed routinely, as are internal visual inspections.
I agree that can be a concern for some organizations, but it doesn't sound to me that Intrawest falls into that category. Oil debris monitoring is not mean't to completely automate the process or replace inspections and checks by humans. It should complement the process, especially where a condition-based maintenance program is in place. The three big advantages of the technique are 1) much earlier detection of damage at the point of initial spall, 2) continuous indication of damage severity/damage progression and 3) a reliable and easy to interpret condition indicator.

Aircraft gearbox chip-detectors cost $300 ea, and although a very simple & inexpensive device, would certainly would have alarmed well ahead of the recent catastrophic gearbox failure at DH. Your device has to clearly provide superior value & function if you want the market to respond.
I don't yet know what failed in the gearbox at DH. It's possible that something fractured suddenly, possibly due to a defect or metal fatigue. Oil debris monitoring/oil sampling/chip detectors probably would be of no use for that failure mode. That is why regular detailed internal inspections should not be replaced. The design of the gearbox needs to be carefully looked at and a usage monitoring program estalished. In engineering terms this is referred to as Reliability Centered Maintenance (RCM) Analysis. "Run-to-Failure" is one possible outcome but I doubt that should apply for the ski lift gearbox because it is safety critical and economically not viable unless you have quick access to spare gearboxes.
Automatic gearbox oil temperature monitoring w/alarms, is very common.
Research (by NASA and others) and experience has shown that chip detector and temperature monitoring can only provide indication of severe damage, often when it is too late (i.e. the gearbox has already reached failure such as lost ability to turn the rotor to keep a helicopter flying). Chip detectors have been used for 50 years but continue to be a source of false alarms caused by fuzz (fuzz=build-up of very small, normal wear particles).