Overhead Crane and Hoist question. How are they designed and manufactured? 1

[BSMEclassof2012]

Dear Engineers,
I recently received a job interview call for a mechanical design engineer position, who will be working to design overhead Cranes and Hoists. This company designs and manufactures overhead crane and hoist systems along with support structures & custom mechanical equipment for industrial, municipal and government facilities. The interview is in a week and I want to learn everything about the design and manufacture, problems, and challenges that are faced by engineers in designing these cranes. Can you please give me some idea what I should focus on? How can I learn in short time about the design of these cranes, if you have experience in this field. What are the codes and calculations involved in the design of these cranes? Thanks

 

[BEMPE16524]

try see my attachment.

 

[LittleInch]

Search in this site on "overhead crane" and "hoist" and you find posts like this.

http://www.eng-tips.com/viewthread.cfm?qid=192420

and

http://www.eng-tips.com/viewthread.cfm?qid=343069

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

I would hope this position is a very junior role at this stage.

There is no second chances in crane and hoist design, it has to be right the first time as peoples lives depend on it.



It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[chicopee]

Research the ASME/ANSI standards if it is a job within the USA. I am sure that this company will educate you before you do any serious design work.

 

[HPost]

If you are in the European Union, then you'd be well advised to look at the Lifting Operations and Lifting Equipment Regulations 1998 (LOLER).

Everything has to comply to the these regulations and even if you are somewhere other than the EU, it will still give you an insight into the design considerations.

 

[zeusfaber]

Story told to me twenty+ years ago by a (then) old aerospace engineer who, as a young man, had done a placement with a dockyard crane maker.

"I've done all these calculations...."

"Very nice - but the first thing we do here is to add an eighth of an inch everywhere for corrosion"

At interview, don't forget to demonstrate a bit of understanding for the real world, as well as being able to talk about the Codes.

A.

 

[JohnRBaker]

While this has nothing to do with the design of overhead cranes (well, maybe not), this story is something that a young machine designer should find helpful.

When I was starting out my engineering career nearly 50 years ago (I was working as a machine designer for a multinational corporation that manufactured capital machinery for the food and chemical processing industries), one of my early assignments was to adapt a new style conveyor to an existing oven used to bake bread (now these were for very large automated commercial bakeries). Anyway, I jumped right in as this was going to my chance to show-off to my management what I was capable of. Now it was not a really complicated project as the basic conveyor design already existed just that it had not been used for the feed and discharge conveyors of this particular oven model. One thing I noticed immediately was that it appeared that the drive-train combination of motor and gearbox was way oversized so I saw this as my chance to not only get the design right, but to reduce the cost as well. So using all of my newly acquired engineering skills I did the power calculations and looked at alternative motor/gearbox combinations and came up a much less expensive set-up. I replaced the existing 1 1/2hp, 1200 rpm motor with a 1/2hp, 1800rpm motor along with the appropriate reduction in the gearbox size, chain drive and sprockets, etc. Well, when I submitted this proposed redesign to my boss he asked that I go with him to the shop where there happened to be in production an oven similar to the one that this conveyor would be incorporated into. As he pointed out certain aspects of the machine he kept noting the electric motors being used and the size of the chain drives for the various parts of the machine, including the feed and discharge conveyors, which of course were still of the old existing design. And about that time he further pointed out that every single electrical motor used in this oven (except for the exhaust fans as they were special high-speed, low-torque motors) were 1 1/2hp, 1200rpm, flange-mounted, with the junction box on the right side of the housing and the chain drives were all 5/8 inch pitch. And the reason for this: So that our customers would only have to keep in their inventory of spare parts for this oven ONLY one electric motor and one stock of roller chain and links, ones that could replace any of the half-dozen or so motor/drive chains that were used for the mechanical drive aspects of the oven's machinery. BTW, this is exactly along the lines of the story related here by zeusfaber ;-)

These are the sorts of lesson that are overlooked in engineering school when we were taking our machinery design classes. It's also the sort of thing that you probably would never even read about (except perhaps in a forum like Eng-Tips). So, as suggested before, you'll need to get some real first-hand knowledge before you could consider yourself qualified for a job like this, so if you continue with this effort, be humble when you talk to your potential new employer and tell them that you're eager to learn the tricks of the trade as well as bringing your current, if still green, talents to the job.

And for the record, while I only spent 14 years of my nearly 50 year engineering career working as a machine designer, they were very rewarding for it was a chance to see your own ideas fleshed-out in iron and steel, a permanence that many people's ideas will never enjoy.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[chicopee]

You may also try to get a catalog of their products as a starting point as there is a lot of engineering information that would be useful in understanding the application of their products and the related industries using their products, extent of their sales force, ancillary services offered to customers, etc...

 

[kingnero]

If in Europe, the eurocodes also extensively describe cranes.

 

[SJBombero]

Overhead cranes in the US as least are usually designed to CMAA 70 or 74 specifications.

 

[moon161]

A large part of mechanical engineering is 'make it like this but...', so taking the 'like this' example and generating modifications related to 'but...'.

An overhead travelling crane can be someplace between bigger than a compact car, and stupendous. They operate in environments between an aircraft assembly factory, a seaport and nasty places where fresh air for the engine and the operator is required.

The job might include or be related to any or all of the lifting (e.g. drum winches), pendant or cab controls, feedback controls systems, support systems (big fabricated beams) traverse systems (e.g. steel wheels on rails like train tracks), and keep adding.

At some point in the chain, there is an engineer that evaluates the various calculations and specifications and formally assumes risk personally (PE) or approves for the company (company assumes risk).

It could be application engineering (based on your requirements, I suggest the model 867-5309 crane w/ soft serve ice cream dispenser).

This wheel has already been invented, but it has to be sized, stretched or cut to fit and followed from mfg to install and commissioned, service contract sold & signed off is better.

Awareness of or familiarity with fabrication, welding, machining and getting people to make something happen, and or learning from them and not get hurt in the process would all help.

 

[jpankask]

Here's a sober lesson of what can happen when the engineering is not correctly performed for an overhead crane/engineered lifting assembly.

http://enformable.com/2013/05/healthy-discussion-of-the-arkansas-nuclear-one-accident/

Link

 

[JohnRBaker]

jpankask, your link is bad...

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[kingnero]

http://enformable.com/2013/05/healthy-discussion-of-the-arkansas-nuclear-one-accident/

 

[BSMEclassof2012]

Thank you everyone for interesting and informative responses. I checked the link and realized how critical the design of these cranes are. Thank you again.

I have another question here. Which industry do these cranes and hoist system fall into? What are you views on the future forecast of these crane systems? If you were in my shoes, would you enter in this industry?