This is the second installment of a two-part blog. Where the first article guided purchasing decision-makers on putting together an overhead crane specification, this part helps them compare bids for buying a crane. It assumes that the guidance in the first blog has been followed and the proposals closely match the tailored criteria as outlined in the spec.
First, be mindful that selecting a crane represents a fantastic opportunity for a facility and the individual/s responsible for the decision. As I said in the first part of this blog, a purchasing decision-maker might only ever have the requirement to buy, say, five or 10 cranes in their whole career. It’s a rare challenge to relish. Choosing wisely will result in enhanced productivity and safety, while the new crane will directly impact the bottom line. Promotion, career development and an incredible sense of satisfaction are all up for grabs.
Made to measure
Clear a big space on the desk and analyze the building’s specifications and technical drawings. As much as the information one has received from the crane companies is important, it’s just as crucial to match and compare their data with the site where the crane will be installed. Has the crane builder accounted for all the requirements outlined in the spec? Have they noted the runway dimensions? What about the unique production line requirements of the facility?
Make sure the manufacturer’s name and model number are included for all parts and components, including the hoist trolley and end trucks. Some independent dealers will try to find wiggle room in specifications by down- or up-rating components. This will reduce the life of equipment and result in costly, time-consuming repairs down the road even in the short term.
There is no reason why an end user shouldn’t contact crane companies to ask for clarification or question certain bidders as to why their model numbers are different to another proposal. Go beyond that and request a detailed explanation; have them outline why those model numbers have been chosen and how that reflects the lifting demands and duty cycle of the application. It’ll soon become apparent if the components have been downrated with good reason, or not. If it’s the latter, consider where else that bidder may have cut a corner. Or better still eliminate them.
As we’ve explored before, the Crane Manufacturers Association of America (CMAA), an independent incorporated trade association affiliated with Material Handling Industry (MHI), rates the duty of overhead cranes from A to F. Class A covers cranes on standby or used for infrequent service, while Class F covers continuous severe service cranes.
When comparing CMAA duty ratings, it’s important to have access to structural and electrical detail. It doesn’t actually cost a crane builder a lot to meet electrical requirements but the additional steel and more demanding manufacturing processes involved with meeting the full criteria of, say, a Class E crane are significant by comparison. All facets of duty cycle rating should be stated.
Hoisting equipment
Remember, there is a different duty cycle rating for the hoist than for the bridge. Here in the states that might be from the Hoist Manufacturers Institute (HMI), another MHI trade group. Confusingly, CMAA and HMI guidelines don’t lineup exactly, as the CMAA ratings system doesn’t state the equivalent hoist rating that should be used for a particular duty crane. Make sure to compare the hoist “H-rating” such as H4, H5, or H6, between competing proposals. There is a way to use the lifespan of bearings to get the two to tally. For example, if a Class D crane has a bearing life rating of X, a comparison can be made with HMI documentation. In Europe and other regions, different guidance is at play.
If there’s apparent consistency between CMAA, the end user, HMI and all the front-running bidders with regards to the duty cycles of the crane and hoist in question, there’s a good chance everyone is on the same page and proposals will need to be differentiated elsewhere. Again, if there are discrepancies, address them. Abuse of cranes can typically be seen in the brakes, wire rope, hoist, bridge and trolley brake (pretty much in that order) so variation between proposals is a critical determinate.
Another thing to look at closely is trolley and bridge trucks; a purchasing decision maker of an overhead crane should demand rotating end trucks. The alternative (fixed axle) is a low budget solution and will result in those problems in future that we all want to avoid. An overhead crane by its very nature comes into its own over a lifetime of ownership. It is a long-term investment and the components need to be consistent with that ethos.
Also compare lead times and details about delivery. It’s perfectly acceptable to ask for reference letters from other companies who might have recently sourced a crane from a supplier one is considering. Did they deliver as their proposal suggested? If not, what problems were encountered and what reasons were given? Did they plan site access and keep disruption to a minimum? Did they accurately estimate the installation time?
Beware of the parts commonality theory. The specification shouldn’t have been based on brands or products that are already in operation at the facility and nor should the proposals. It’s a myth that getting the same brand of crane that has been used elsewhere or sourcing a like-for-like replacement as the predecessor, is advantageous from any viewpoint. I once lost out on a bid because the crane owner wanted parts commonality with an existing crane. It turned out that given the evolution of the product, the only commonality he ended up with was the paint! Motors, gearboxes and brakes, etc. that he hoped would be consistent were all different.
May the source be with you
Crane builders should be quizzed on where they source their parts. At Ace, for example, we make our own gears and gearboxes, a unique feature of which is a horizontal split so they are easy to rebuild whilst on the crane. Most gearboxes on the market have a split in the side so they have to be removed and rebuilt offsite. Where possible, we believe in making parts serviceable on the crane and that’s something I’d urge buyers to look for in proposals.
It’s not all about manufacturing in-house, however. Conversely, we source only branded controls, motors and brakes from leading manufacturers in those product sectors. Further, they are all based in the U.S., where parts are readily available. Look at proposals carefully and consider the problems that could be encountered if parts are originally from Europe and not even stocked in North America. If there’s a breakdown, an item could take two weeks to ship.
For similar reasons, on heavier-duty cranes, stick to imperial measurement wire rope that can be readily sourced domestically. If a supplier is working with metric wire rope, it might be difficult to locate the manufacturer if there is a problem with it. In all cases, where a crane builder says they have got stock or access to the original source, ask them to prove it. Take the time to visit the supply warehouse and speak to representatives of their supply chain to verify the information.
That would also serve as a good way to check on the location of suppliers. Is the address on the proposal where the parts are stored or is it only a satellite office? Closer isn’t always better—a strong bid from someone two hours further away than a company that has submitted a weak one will win every day—but there better be a good reason to use a New York-based supplier for a standard crane installation in California.
There’s much to be gained by choosing the right supplier of the right crane. As the last two blogs have explored, issue a detailed specification and be diligent when comparing proposals.
Thank you for reading. Follow us on Twitter at @AceWorldCompany
Tad Dunville
Director of Corporate Development, Ace World Companies
Membership Committee, Crane Certification Association of America
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