Since I have been selling and consulting with customers on overhead bridge cranes, I have
received several quote request for hoist with load brakes. Mostly these are
government or military specifications, but also a few private companies request
the same. There are only three reasons why this would be listed in someone’s
specifications today. One, it is the same spec they have used for decades so
the easiest decision for those that know little about cranes to just continue with
this decades old specification. Two, someone actually believes that is a
requirement set by CMAA or other governing body. Or three, they honestly
believe they are getting a safer more reliable crane with a load brake Well…
all three are wrong and I will explain why.
First off you need to understand what the load brake is for. The mechanical load brake controls the speeds when lowering the load, and helps to hold the load when the motor is not running. The holding brake actually works together with the holding brake. The Weston Style brake only holds approximately 25 to 30% of the load while the holding brake does the rest.This is really what the load brake is for but I honestly don't feel that is why you see in many government specifications. You can check out my more popular post Mechanical Load Brake Operation and Inspection. Here you will get a basic introduction to the load brake and learn about a few misconceptions about it.
Most hoist today do not have mechanical load braking
technology in them. This is because it is outdated and does not fit the
technology of our electric motors today. A load brake does not make your crane safer.
Many manufacturers who used to have load brakes in their equipment stopped decades ago. Yet, here we are still with new specifications requesting load
brakes. The load brake was designed to control the load in it’s decent. In an
emergency it should hold the load as well. This form of technology worked great
back when all the hoist motors were wound rotor. A wound rotor motor cannot
stop acceleration of the load from gravity. Therefore, load brakes were
required for hoist and you certainly wouldn’t want to use a hoist without it. Today’s
technology uses Squirrel Cage Motors. See video below for a two minute introduction. Squirrel cage motors are fully capable of
regenerative braking. This technology meets all CMAA Spec 70 requirements.
What about Variable Drives? Not only are load brakes not
required with today’s technology, today’s technology does not work with load
brake hoists. If your hoist has a load
brake you can forget about variable drives. You cannot get the speeds accuracy
in a load brake hoist. Variable drives do not work with load brake hoist. You
will have constant issues with your load brake and will become a safety and
efficiency issue. If you need speed control on your hoist, and you have a load
brake hoist, you will be out of luck.
So why do we need load brakes in all these government and
military specs? If you ask me,.. I think it is a complete waste of money to
invest in such outdated technology. It would be like going to Ford and asking
them to remove power steering because you feel it would be more reliable
without it. Just makes no sense. Don’t forget all the cost that is associated
with your load brake hoist. That baby will need to be opened up at least every
four years to verify the load brake is functioning properly, and re-adjust the
air gap. The load brake is buried in your gear case; it is a very costly inspection.
The brake works off of friction so it has pads or liners that wear causing it
to need replacement periodically. Typically, it is best just to change them out
during the inspection anyways. The labor to change them is more expensive than
the liners so it is the perfect time. Your oil in the gear case will also be
contaminated with the lining wear and dissipated heat from the load brake which
will also affect your entire gearing in your gear box reducing the life of
those gears.
Let’s also not forget that when you have high capacity
cranes, or in process cranes you do not want a load brake. They create a lot of
heat when stopping a load so it is very impractical for a process crane. This
would also apply to any crane that would require a permanent below the hook
device. If a below the hook device is connected to the load block permanently, the
load brake is going to seize up causing costly downtime and repairs.
Today’s motor themselves are the secondary control braking
function that is required by OSHA. Because people don’t really understand this
process they disregard it altogether. The squirrel-cage motor functions using
regenerative braking if the load tries to pull faster than the motors rated
speed. Regenerative braking does not generate a lot of heat so it is a safer
application for large capacity cranes and process cranes.
Hopefully in the near future we will start to see the industry change to where there will be no more request for outdated technology. It all starts with the best overhead crane companies training their customer's about the latest safety features available for their crane. You will get the safest cranes on the market using today's technology.
New technology is developed for three simple reasons: to have
an easier life, to save a life, or to save us money. With the innovations of
overhead crane technology, the same applies. When you think of the future of crane
maintenance what do you think about? For all the crane operators out there we
know that the way they operate has changed drastically. Variable frequency
drives have allowed operators to be more efficient and safer when operating a
crane. But what about servicing a crane?
Has anything changed there? Is there any difference from the way a crane is
serviced yesterday or today and way it will be serviced 10 years from now?With the technology that has been developed
in the last 20 years I am in wonder of what the future could hold for crane
maintenance. I have been amazed at the advancements
in overhead crane maintenance in recent years. A lot has changed but do you
know about it?
When an overhead crane technician troubleshoots your
crane they are inspecting as they see it. Just like an auto mechanic, if your
crane is acting up but works fine during the troubleshooting process it is
harder for the technician to find the problem. Several innovations such as
condition monitors have been developed over the years from a few crane
manufacturers that would allow the technician to see past history of the cranes
usage. This helped them see any issue that may have caused a crane malfunction.
This could be overloads, usage hours, crane
starts, load swings, and overheating. However, this is by far not new crane
technology. This was the newest technology over two decades ago. Data
collectors have been available since the 80’s.
The future of crane maintenance takes “proactive” to a
new level; technology that can predict when there will be a crane failure. Imagine being able to troubleshoot your crane
without stopping production and without even dispatching a technician to your
site. You could find symptoms of wearing components before they are problematic
and get the components replaced reducing costly downtime, or getting a text
message telling you that a crane operator just picked a load over capacity.
This is an excellent way to monitor your operators habits and will help focus
on operator training that may be required. This technology is real time analysis and
remote monitoring. Real time analysis is a safety, and production feature that
was not available previously. With this newest technology you have the ability
to find an issue before it becomes a breakdown. Real time analysis has been
available for quite some time. Over the years I have seen real time analysis on
my customer’s equipment in their facility. On overhead cranes however this is a
new idea; an idea that will revolutionize the crane servicing industry. Just
think that before you have to place a trouble call, someone is already
monitoring your crane. If an issue develops then a remote team has the ability
to troubleshoot your crane without even being on your property. This is a time
and money saver especially if your overhead crane maintenance provider is not
nearby. If there is a need to send a
technician to your site, the remote team representative will call you and
inform of what they found. The reports will also inform you if you have a piece
of equipment that is not suitable for the application that it is being used
for.
This is an evolution of overhead crane maintenance. Maintenance can now be performed based on
actual usage instead of a calendar. This future technology is available now on
select Konecranes CXT wire rope hoists and Smarton® cranes. The technology is
called TRUCONNECT®. You will be able to monitor your crane usage in real
time online. Usage data will be reported in graphs to help you analyze the data
making it easy to read. This data will allow you to optimize your productivity
and your crane maintenance by viewing the life cycle of your hoist. This life
cycle analysis will keep you better informed for future decisions. Safety alerts sent straight to your phone
notifying you of safety issues that can be addressed immediately instead of
after the fact.
With the development of overhead crane service technology
you will get a more reliable, safer crane, and lower your investment cost at
the same time. This future technology that is available for you today is only a
starting point. The future holds so much
more. I recently watched a video that shared these same views.Companies that invest in innovation will be
the leaders to develop and utilize
technology like hybrid service vehicles,
crane scanning visors, carbon nano-fiber hardhats, self-lubricating wire ropes,
hydrogen powered cranes, and 3D laser printers that can make crane parts
quickly during breakdowns. These are ideas that only Walt Disney himself could
have dreamed up. But, like says, “If it can be dreamed, it can be done”.
