Dearborn Overhead Crane

Last week I talked about the folly of OSHA not requiring “overload protection”.  I have received a number of questions and let me therefore take a moment to answer them all at once.

• Wire rope hoists are NOT required to have any type of overload protection
• Electric Chain hoists ARE required to have some form of overload protection
• There are several brands of overload protection that will fit almost all brands of hoist
  • they are reasonably priced
  • the installation will likely cost as much as the materials
  • on most systems, a fair amount of head room is lost

The topic of the day is a particular type of “overload protection”, that is cranes with two hoists.  We frequently are asked to supply crane that have two hoists for flipping a die.  In this case either hoist may be required to lift the full load, lets say 5 tons, but never will the sum total of the lift be 5 tons.  In other words, we have to supply a 5 ton crane with two 5 ton hoists.  This may sound like a time bomb ticking, but with modern controls, there is an easy and economical answer.

LOAD SUMMING

Most hoist manufacturers and several third party after market control manufacturers now supply a small control system that is installed into the hoist control panel that constantly sums the total weight lifted by the two hoists.  With this, either hoist can lift the full 5 tons or can share the 5 tons in any combination.  As long as the aggregate total does not exceed the 5 ton load limit. the units operation is totally transparent, but in the event 5 tons is exceeded, the hoist will cease to lift and only operate in the down direction.

If you have any questions, give me a call.

Larry Dunville

800-Crane58

Next week I’ll start to get into an inexpensive way to drastically cut down on wheel wear.

One of the most confusing issues regarding Overhead Bridge Crane rules and regulations is, “Who’s the Boss”? In other words, what laws govern the crane owner and for that matter, the crane builder?

I guess you should start with OSHA 1910.179. It quite frankly lays down the law in surprisingly few areas. That is surprisingly few concrete specifics. What it does is, “incorporate by reference”, a couple dozen other reference specifications. In other words, the CMAA 70 and 74 specifications are incorporated by reference, which means they have the same force of law as OSHA 1910.179. That means for example, the two referenced CMAA specs along with about 2 dozen other specs are therefore within the scope of 1910.179.

As if this referenced body of work is not enough, each of the referenced documents, in turn, incorporate by reference other specs. In the case of CMAA, we’re talking another couple of dozen specs which they reference, including such things as the National Electric Code, AWS welding code, etc.

To add one more layer to this circus of specifications, OSHA also “incorporates by reference” the manufacturers “owners manual” as the ultimate authority on that piece of equipment.

So the next time you get asked a question regarding the “legitimate way” to do something on your crane or hoist, be prepared to invest a lot of time wading through a lot of specs. Many of which cost close to a hundred bucks each. Below is a PDF files that is a map to all the related governing bodies and specification for Overhead Bridge Cranes and Hoists. To date, I have 36 listings, I’m sure you will have more to add and would appreciate your input.

Overhead Crane Governing Bodies

Until next week.

Larry Dunville
PhD in Craneology
(Piled High and Deep)

I’ve had second thoughts about using this as my first titled entry, but I want it to set the tone for the level of candor to be expected for this blog. So here we go…

Dearborn Crane is a crane builder and buys the hoists that go on our cranes from various hoist manufacturing companies. More than a decade ago, one of our major hoists suppliers introduced their new line of “up-rated” hoists. At our office, he sat us down and showed us the newly printed catalogs in which all his hoists were now rated as H4 duty cycle, rather than the previous mix of H2, H3 and H4 hoists.

For those of you not acquainted with the HMI’s (Hoist Manufacturers Institute,) duty cycle rating system, HMI is an industry association of member manufacturers that have set down a series of specifications for the hoist industry. The system rates hoists based on a duty cycle based performance with ratings between H1 (lightest duty) to H5 (heaviest duty).

The H3 hoist is considered to be a “standard” duty hoist and the h4 is the beginning of the “heavy” duty hoists. Prior to this time, most manufactures had a mixed line of offerings including, H2, H3, H4 and H5 hoists, but at this meeting we were being told that this supplier had only H4 and higher hoists from this day forward.

After show us the new catalog pages with the H4 designations, the conversation went something like this;

Q. How much is the price increase for the new higher rated hoists?

A. No price increase.

Q. Is this a new line of hoists?

A. No, this is the same product line as before.

Q. Larger horsepower motors, better insulation?

A. No, they have the same motors.

Q. Larger ropes?

A. No, same ropes.

Q. Bigger gearboxes, larger contactors….what’s the difference???

A. Quite frankly, the only difference is that the printer changed the catalog pages from H3 to H4. We did some figuring (he probably didn’t use that exact word, but I think it fits here perfectly) and we determined that all our hoists meet the HMI H4 requirements, so we had the catalogs reprinted with every hoist at a minimum of H4…

At this point, I’m sure you want to know who would be so unscrupulous. Well let’s put it this way, today I’m afraid you would have an easier time finding a living dinosaur than a H3 hoists in any manufactures catalog! Who’s at fault? Let me give you my list in David Lettermen fashion.

1. The manufacturers who seem to be willing to do anything to make a sale today, regardless of warranty costs later and loss of long term reputation in the market place.
2. The manufacturers association, which are simply a reflection of its members. If they are willing to craft a spec that is so loose, that it no longer means anything, then why have it??? Let me put it this way, when even a lowly chain hoist has a H4 rating (and they ALL do), then the designation is meaningless. Worse yet, they are miss leading, in that they give the impression of being something they are not, thereby deliberately deceiving and misrepresenting.
3. ME AND YOU, the buying public. We have been so taken with marketing hype that we no longer use our head and do our homework. Try buying a small Coke at McDonalds. You can’t, they only have medium, large and extra large. They think that getting a “Super Meal” with a medium drink sounds better than getting a “Super Meal” with a small drink. Even if both of them only have a 12 oz drink?

What can we do?

Do your homework, don’t just flip to the back page and read the bottom line, read the whole document. Price should not be the only factor in your decision. If it is, don’t blame the manufacturer for supplying junk, we have all made ourselves into willing participants.

1. Read the whole quote, not just the price

2. Make a comparison matrix. If you don’t don’t know the critical issues, ask each of your bidders. Yes, they will each highlight their own strong suits, but their combined list should be as comprehensive as you can get.

3. Send the new combined matrix back to each of the bidders and have them fill it out. Stipulate that is there are any blanks, they should not bother to re-submit their quote.

4. If you’re not sure of their response, put it into your own words and then use the matrix as part of your contract/purchase order.

Is this air tight, no way. But it’s a lot better than what you probably have now.

A point to consider;

The old AISE (American Institute of Steel Engineers) had buyer generated specifications as opposed to manufacturers written specs. They had their flaws, but were more effective than the nothing we now have.

HMI website address: www.mhia.org/psc/PSC_Products_Hoists.cfm

Establishment of an Overhead Crane Knowledge Base

August 14th, 2007

Welcome to our Blog.

From now on, I intend to post at least once a week and more if time permits. At the beginning, I will pull my topics from points of confusion that I have seen over the past 30 years in the Bridge Crane business. Ours is a family company that was started by my father and uncles in 1947 and I have been involved in overhead bridge cranes all of my life. I’ve seen just about every crane problem you can imagine and look forward to putting together a knowledge base here to help people avoid those all too common as well as not so common mistakes.

I once purchased a book entitled “If Only We Knew What We Know”. I spite of the apparent double talk, the title really struck me. It was my first exposure to “knowledge bases” and the concept really caught my imagination. Nowhere is the concept of a knowledgebase more applicable that with overhead bridge cranes. There are hundreds of experienced crane technicians, plant engineers, and maintenance men and crane operators with 10, 20 and 30 plus years experience that have learn the hard way, but there is almost nothing written down to pass on this knowledge. This is the essence of a Knowledgebase, and this is what I hope to collectively put together here.

In the process of putting this together, I look forward to reviewing your comments and feel free to disagree as well as to start a entirely new topic of conversation. If you prefer not to write for public consumption, feel free contact me directly;

My address is-

LDunville@DearbornCrane.com

My phone number is-

574-259-2444

Some of the upcomming topics will include;

• The important of Duty Cycle in specifying and purchasing an Overhead Bridge Crane
• OSHA, what is really required?
• Do Mechanical Load Brakes really make a difference?
• Six issues you must confirm before buying an Overhead Bridge Crane

Look forward to hearing from you.

Dr. Frazier Crane

PhD. in Crane-ology

(PhD. = piled high and deep)