This is the most important thing to
know over anything else. Depending on the application could change many of the
deciding factors on what kind of crane you will need. For example certain
chemicals can make plastic brittle or accelerate metal corrosion. Cutting oils
can make neoprene and PVC brittle. Heat and moisture can cause your motors to
overheat. You will not pick the right crane without the crane company knowing
what the application is. Your crane will
need to come with certain components depending on its application. To know your
application you will need to know what you’re picking up, and the environment
in which the crane will be used. Added components will be required for areas
with heavy dust, humid, high or low temperatures, outdoor, indoor, chemical
exposure, Light, and even altitude can affect the crane. Outside of the
standard range, additional components will be required.
Look out for these items on your
application.
·
Standard Altitude is Below 3280ft (Altitude can
affect cooling of electronic components and not allow heat dissipation)
·
Standard Temperature Range is 32˚F to 104˚F
·
Standard Humidity is below 90%
·
Outdoor Applications will require features to
prevent damage during rain, snow, ice, heat, wind, and ultraviolet radiation.
·
Corrosive
or Explosive Chemicals/ Fumes will require added features
·
Heavy dust environments from cutting will
require protective added features
·
Heat can liquefy lubricants, and affect motors,
and electrical components
·
Cold can freeze lubricants, crack plastic
components, and electrical parts
·
Drastic temperature changes can cause
condensation and short out electrical components and cause corrosion
2. Duty Cycle
The crane’s duty cycle is going to
depend partly on the application. If the crane is a production crane it will
probably need a heavy duty cycle. If it is a maintenance crane or a crane used
for shipping then the cycle may be shorter. You will need to ask yourself how
often will this crane will get used every hour and how often will it be lifting
near full capacity? Depending on this, different components will be used to
make your crane. Electric motors have duty cycles and you want to make sure
that your crane has the right motor for the job. Picking a severe duty motor
for a light duty application will just cause you to spend well over what is
required for the application.
There are two standards crane manufacturers
go by when picking out the right duty cycle. FEM and CMAA. CMAA is the Crane
Manufacturers Association of America and FEM is Federal European De La
Manutention. This is the standards for design and manufacturing internationally
of overhead traveling cranes. Both specifications are written based on the
input from the larger crane companies. The difference is that FEM is worldwide
while CMAA is the United States only. FEM will also separate each main part of the
crane (hoist, trolley, and bridge) while CMAA specs classify the crane as a
whole. To understand these classifications you will also need to understand
what a lift or work cycle is. A work cycle is lifting the load, having a rest
period where the trolley or bridge is moving, lowering the load, having a rest
period again where the trolley or bridge may be moving, and then returning the
hook to the starting position.
FEM Class Definitions
1Bm
·
Light Loads less than two hours per day
(Occasional full loads, Usually light load, Small fixed load)
·
Medium loads less than one hour per day (
Occasional full loads, usually light load, Average fixed load)
1Am
·
Light Loads less than four hours per day
(Occasional full loads, Usually light load, Small fixed load)
·
Medium loads less than two hours per day (Occasional
full loads, usually light load, Average fixed load)
·
Heavy loads less than one hour per day
(Repetitive full loads, Usually average load, Heavy fixed load)
2m
·
Light loads less than eight hours per day
(Occasional full loads, Usually light load, Small fixed load)
·
Medium Loads less than four hours per day (Occasional
full loads, usually light load, Average fixed load)
·
Heavy loads less than two hours per day (Repetitive
full loads, Usually average load, Heavy fixed load)
·
Very heavy loads less than one hour per day
(usually almost full loads, Very heavy fixed load)
3m
·
Light loads less than sixteen hours per day
(Occasional full loads, Usually light load, Small fixed load)
·
Medium Loads less than eight hours per day (Occasional
full loads, usually light load, Average fixed load)
·
Heavy loads less than four hours per day (Repetitive
full loads, Usually average load, Heavy fixed load)
·
Very heavy loads less than two hours per day
(usually almost full loads, Very heavy fixed load)
4m
·
Medium Loads less than sixteen hours per day (Occasional
full loads, usually light load, Average fixed load)
·
Heavy loads less than eight hours per day (Repetitive
full loads, Usually average load, Heavy fixed load)
·
Very heavy loads less than four hours per day
(usually almost full loads, Very heavy fixed load)
5m
·
Heavy loads continuous use per day (Repetitive
full loads, Usually average load, Heavy fixed load)
·
Very heavy loads continuous use per day
(usually almost full loads, Very heavy fixed load)
CMAA Class Definitions
This service
class covers cranes which may be used in installations such as power houses,
public utilities, turbine rooms, motor rooms and transformer stations where
precise handling of equipment at slow speeds with long, idle periods between
lifts are required. Capacity loads may be handled for initial installation of
equipment and for infrequent maintenance.
This service
covers cranes which may be used in repair shops, light assembly operations,
service buildings, light warehousing, etc. where service requirements are light
and the speed is slow. Loads may vary from no load to occasional full rated
loads with two to five lifts per hour, averaging ten feet per lift.
This service
covers cranes which may be used in machine shops or paper mill machine rooms,
etc., where service requirements are moderate. In this type of service the
crane will handle loads which average 50 percent of the rated capacity with 5
to 10 lifts per hour, averaging 15 feet, not over 50 percent of the lift at
rated capacity.
This service
covers cranes which may be used in heavy machine shops, foundries, fabricating
plants, steel warehouses, container yards, lumber mills, etc., and standard
duty bucket and magnet operations where heavy duty production is required. In
this type of service, loads approaching 50 percent of the rated capacity will
be handled constantly during the working period. High speeds are desirable for
this type of service with 10 to 20 lifts per hour averaging 15 feet, not over
65 percent of the lifts at rated capacity.
This type of
service requires a crane capable of handling loads approaching a rated capacity
throughout its life. Applications may include magnet, bucket, magnet/bucket
combination cranes for scrap yards, cement mills, lumber mills, fertilizer
plants, container handling, etc., with twenty or more lifts per hour at or near
the rated capacity.
This type of
service requires a crane capable of handling loads approaching rated capacity
continuously under severe service conditions throughout its life. Applications
may include custom designed specialty cranes essential to performing the
critical work tasks affecting the total production facility. These cranes must
provide the highest reliability with special attention to ease of maintenance
features.
3. Capacity
Picking
the right capacity is very important to not only picking the right duty cycle
but also extending the life of your crane. For example you may have a product that weighs
10 tons. However, do you have other product that the crane will be picking up
that weighs less than 10 tons? It may be more ideal to increase the capacity of
the crane to 15 tons and keeps a Class C rating instead of increasing the
rating to Class D. A ten ton crane may
be your best option as well if most of what you are picking up on weighs five
tons. It all depends on the loads and they need to be taken into consideration
not just the largest weight requirements. You should also think about any below
the hook requirements that may be needed to pick up your product. Sometimes the
below the hook device can weight several tons. This will have a great impact on
the crane requirements.
I
would say that out of these ten things to consider, speeds is what gets missed
the most. Typically the standard speeds will work for most applications, there
still are some applications where you will need faster or slower speeds. Depending
on the capacity the hoist speed will vary but your bridge and trolley speeds
are fairly close regardless of speeds. A typical bridge speed is around 100 fpm,
a trolley speed is around 70 fpm, and the hoist is between 30-60 fpm depending
on capacity. Depending on the application you may need higher speeds. If you
have a crane that is feeding your facility with raw material or loading the
finished product such as rebar you may need a high speed crane that would not
come with the standard features. The last thing you want is to purchase a crane
to increase production and find out that the crane operates too slowly. You may
also have an application where you need to utilize the crane for assembling a
product. This often requires precise lifting and very slow speeds. If you
purchase a standard crane the speeds will be too fast for this application
making the load jerky and you will not be able to assemble your product using
the crane. Take the time to discuss the required speeds with your crane
company.
You will also need to know any safety
issues for the application that may exist for the crane operator. Perhaps radio
control will be required, or a cab, perhaps even automation. Depending on what
the operator is exposed to you may need something other than pendant
control. Lighting may also be something
you need to think about. If your crane is large it may cover much of the
overhead lighting. Often lights will be provided on the crane to help the
operator and workers see when it is blocking the overhead lights. You may also
need a cab control if you have chosen high speeds for your crane. Can the operator keep up with the trolley and
bridge speeds safely by walking? If not then you should add cab control to the
crane.
When considering your crane control, think
about..
·
Chemical Exposure
·
High or Cold Temperatures
·
Explosive Fumes
·
Lighting
·
Walking Hazards
·
Crane Speeds
Another
factor to consider is where in the crane area do you need to reach with the
load hook? This is called your hook approach. The hook approach end is the minimum horizontal distance that is parallel
to the runway and goes from the centerline of the hook to the centerline of the
runway. The hook approach side is the minimum horizontal distance,
perpendicular to the runway between the centerline of a hook and the centerline
of the runway rail. You will need to know how much coverage your process or
application will require prior to getting crane pricing. A crane consultant or
crane provider can help with acquiring this information.
a. Building
Clearances for hook approach
· Center of runway rail to face of building column or
side obstruction
· Approximate length of runway
· Number of Cranes on runway
· Runway conductor location
· Below the hook dimensions
Depending on
whether you are installing a new system or a new crane on an existing system you
will need different information. Your
lifting requirements will be restricted based on the height and design of your
existing building. If you have an existing runway you will have even greater
restrictions. To get crane pricing you will need some preliminary information.
a. Building
Clearances for existing runway
· Floor to Top of Runway Rail
· Top of runway rail to lowest overhead obstruction
· Runway rail size
· Below the hook dimensions
b. Building
Clearances for new system
· Available dimension from floor to nearest ceiling
obstruction
· Height of product being lifted
· Below the hook equipment dimensions
Another
item to look at when getting crane pricing is the features that your crane will
come with. Many people overlook these and look at price alone. However, these
features can greatly increase your production and is well worth the investment.
Unlike the automotive industry or any other for that matter, you can still
purchase cranes today with decade old technology. This would be the worst
investment you could do for your company. With the latest technology available
you can increase your production and at the same time make your facility safer
for your employees. Certain technology you should never purchase a crane
without. Always ensure your crane comes with variable frequency drive for the
crane and trolley motions. This will ensure safe operation of your crane and
will help in reducing load swings. Radio controls also help keep your operators
away from the load. This is typically an option and is never quoted unless
requested. However this allows your operators to stand away from the load. The
cost to add this on a new crane is minimal and well worth the extra cost.
Another important considerations to think about when you are reviewing your
crane’s technology is real time analysis of your crane’s operation. This is
currently limited in the crane industry but is readily available with certain
manufacturers. Find a manufacturer that will provide at least 6 month
monitoring service for free so you can see how this will benefit your facility.
There are many other features that can be added to your crane today. All are
designed to improve your productivity or make your crane safer to operate. Features
such as sway control, inching, microspeed, slack rope prevention, load
floating, hook centering, follow me, hoist synchronization, extended and
adaptive speed ranges, and shock load prevention, are available and may greatly
benefit your application. Talk to a consultant or your crane provider for
these options.
9. Warranty
When
reviewing your quotes you want to take into consideration your warranty. Not
all warranties are created equal. Key things to look for with your crane’s
warranty is the following..
·
How long is your warranty?
·
Does it include labor?
·
What doesn’t it cover?
·
Is there a local service group that can deal
with warranty issues?
10. Service
Your crane purchase does not end
with the crane installation. During the life of the crane it will require
servicing and sometimes warranty issues. There will also be a need for crane
inspections to meet local regulations and ensure your crane is operating safely
and efficiently. You will also be in the
need of training your operators on your new equipment. When reviewing crane proposals ask about their
service to ensure they have someone local to meet your needs.
Make
you ask yourself these questions
- Ensure that whoever you’re purchasing your crane from they are a turn key supplier. They will provide everything needed to get your crane installed and up and running, including crane commissioning by the manufacturer, and even shipping of the crane.
- Is your quote all inclusive? With the exception of local taxes and certain instances with local permitting it should cover everything.
- Are you purchasing from the manufacturer or a distributer?
- Who will be handling any warranty issues? The manufacturer or distributor? Are they local?
- Is there a local manufacturer representative that can provide training on my new equipment?
- Can the manufacturer of my crane provide periodic inspections on their equipment?
If you review these 10 items prior to purchasing or getting
a quote for your next overhead crane you will be one step ahead and on the
right track to making the best decision for your company. You can always send
me an email or give me a call and I would be happy to consult with you on your
next overhead crane project.
Works Cited
