Questions about elevators

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Hi, I am not in the elevator industry but just was curious to how elevators worked and came up with a couple of questions. I am actually a firefighter with a mechanical background and became interested in how elevators worked after reading an article on elevator rescue.

1.) I was wondering what elevator company you experts think makes the highest quality elevators based on safety, reliability and longevity?

2.) Why do elevator companies still make geared elevators, arenít gearless better?

3.) Do any new installations still use Ward-Leonard Motor-Generator sets or is everything all variable frequency variable voltage AC drives now?

Thanks in Advance,

Constantine Foundos

-- Constantine Foundos (foundosc@msoe.edu), April 14, 2003

Answers

There are many types of elevators. No one company makes the best elevator of all types in my opinion. Between them, the familiar names. i.e. KONE, OTIS, SCHINDLER and ThyssenKrupp make good products of all types. Less versatile as to type, but excellent in quality are the traction elevators made by MITSUBISHI.Certain local or regional firms can supply imminently satisfactory packages for some applications.

Geared machines are often less expensive for certain applications, but with the advent of several technical innovations, variants of the gearless design are "taking over"

M-G drives are still used but less and less. There are certain situations where they still offer certain advantages.

I can basically only address the US; worldwide there are many more players.And of course, this is all just my opinion.

-- John Brannon (akaElevman@aol.com), April 14, 2003.


Dear Connie,

35years in the trade.I have worked for small and big companys...all companys have had good years and What we call thin yearsBut the company that comes to mind for the best all around parts is OTIS there brakes...machines...door lock hardware is far superior to those in the trade..No one installs wardlenard systems anymore,its not cost efective..usually acvf drives is the way to go!

hope that helps!

Docotis

-- Docotis (darkaa@aol.com), April 21, 2003.


Response to DOCOTIS

Sorry my friend but you have a very narrow perspective to state that OTIS excell in all area's, they have good equipment & bad equipment just like everyone else. Thyssen, KONE, Schindler, Mitsubishi to name a few, all have products that rival (quality wise) any Otis equipment out there. It's not possible to declare one company as the best for everything, as they all have their merits & they all make cheap products, to serve that share of the market.

-- Francis Studders (francis1@tinyonline.co.uk), May 04, 2003.

Re: questions.

Regarding Question 1: It depends on the level of service performed, the quality and accuracy of the initial install, and the type of equipment installed with regards to its usage. A. If comprehensive, preventative maintainence is performed, including updates and parts changes prior to wear-out, then the equipment will last a lot longer than the 10 year(or less) industry average between modernizations. B. The accuracy of the initial install is important. Things that don't fit or interact well together will accellerate wear, decreasing useful life, and provide unsatisfactory operation. C. The most common of the problems I have encountered is this one. You have to plan for the real-life usage of the elevator, not the theoretical maximum. If you think you'll get great service out of a hydro that's running constantly, you probably won't. If you think you'll get great door life with cheap doors in a high-use warehouse, you won't. If you think you'll get great service out of 4 elevators with a new-fangled electronic control when you really need six to transport volumes of people, you won't. You have to plan for how many people will really be there, knowing that almost every building built will probably have more than the designed amount coming and going. Include squeeze room to accomodate them. Regarding Question 2: Geared elevators are primarily used for low-speed and/or low usage applications. They tend to be more cost-effective (cheaper) than gearless, and are cheaper to maintain (pulling and repairing a 40 HP standard-frame motor is far cheaper than repairing a gearless motor). Regarding question 3: Usually the only time a Ward-Leonard system is used today (other than a specification) is when it would be more expensive to do the electrical work required to facilitate the use of a drive. Undersized feeders, emergency generators, harmonics issues, etc., all play into this, making the decision one that might preclude the use of a drive due to the expense entailed to support the drive reliably. Modernizations are generally where these issues come up, or sometimes utility issues regarding power factors and line harmonics. VVVF's are nice, but not always cost-effective. If you have a nice Otis gearless, it's probably be cheaper to use a DC drive than cutting a hole in the roof and installing a new pancake motor, and that's if you don't trigger any other code requirements in the process. VVVF mod's are probably well-suited with geared applications (removing DC hoist motor and replacing with AC) due to less brush maintainence and carbon problems, as well as using cheap, standard AC motors.

-- steve (eastlion@pacbell.net), April 24, 2003.

Dear Sir, The answer to your first question: Thyssen Krupp, Otis, Schindler and Kone are probably producing the right products for this matter. You can also assume that some "third party" providers and resellers have the same (or even better) products (because they provide often solutions on demand, what the big four are not doing anymore). Your second question: the gearless solutions are often the best solution (for all of your mentioned arguments) but not at the same cost of a geared solution. It depends on what the customer has as situation: high rise, high speed, low rise, low speed, office building, residential building, traffic demands etc. No simple answer can be given on this question without the specs of the technical needs to a building. As an answer to your last question: Ward-Leonard solutions are defenitely out of fashion. Since the Amps they consume in rest state, it is clear that, environmental effects are not very well received. Ac drives have a benifit in operation conditions, rest conditions and maintenance costs. You might conclude from this that AC-drives combined with gearless machines are the future. (but in the right domain for use).

Kind regards, Manu Verhelst

-- emmanuel verhelst (emmanuel.verhelst@chello.be), September 30, 2003.



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