Ten Things to Know Before Purchasing an Overhead Crane

There are many things to know and understand prior to purchasing an overhead crane. Your purchase is typically to improve productivity and safety within your facility. Therefore you really need to take several things into account prior to your purchase. Lowest bid does not work in the crane industry. There are too many crane variations, safety requirements, and technological features available today that you will miss the boat on if you go with lowest bid. Not only that but you may get a crane that is not even suitable for your application. In the end you will spend too much money on a crane with specifications that are not required for your application. I have seen way too many times bids on overhead cranes that have specs way over what the application requires. This causes them to spend sometimes double the amount for a crane and it does not even fit their application. Before you invest your money into a new overhead crane, take into account these ten items that will not only save you money but you will invest in the best crane for your application.

1.      Know Your Application

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

CLASS A (STANDBY OR INFREQUENT SERVICE)

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.

CLASS B (LIGHT SERVICE)

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.

CLASS C (MODERATE SERVICE)

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.

CLASS D (HEAVY SERVICE)

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.

CLASS E (SEVERE SERVICE)

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.

CLASS F (CONTINUOUS SEVERE SERVICE)

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.

4.      Speed

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.

 

5.      Safety Issues

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

6.      Area Coverage

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

7.      Lift Height Requirements

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

8.      Technology Features

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

http://www.konecranesusa.com/resources/industrial-crane-terminology/girder-bridge-messenger-track

CMAA Specification 70

What Do I Need to Know Before I Buy a Chain Hoist?

There are many advantages to purchasing a chain hoist.  They are low maintenance, lower cost than wire rope hoist, and they are lightweight. Having a lightweight hoist enables the owner to easily relocate equipment when needed. Typically, facilities that often move a process frequently or they install a crane system for a process that will be used temporarily, the chain hoist is the best choice because it can easily be moved from one location to another.

Many people think a chain hoist is a commodity item and lowest cost is the best choice. People will purchase a chain hoist based on price not realizing that many things can go wrong with a chain hoist if it is used in the wrong application, or exposed to an environment that it was not designed for. Or perhaps they purchased a chain hoist not realizing the warranty was too limited to even be considered a warranty by anyone's standards. There are several factors to consider prior to your investment. I have come up with several questions to ask yourself prior to purchasing a chain hoist. These questions will help you pick the best hoist for your needs.

There is no such a thing as a hoist that fits every application. Every hoist is designed to fit within the parameters of a certain application. I have seen time and time again where companies will purchase a hoist and use the same hoist for several different applications throughout their facility. The hoist may last for a while but in the wrong application your hoist can wear faster causing production and safety issues. Many people do not know what they should be looking for when they purchase a chain hoist.

When you are in the market for a chain hoist you need to ask yourself these eight questions…

What is the application?

What are you going to be lifting with the hoist? Are you using it to assemble a product and precision is required? Are you using below the hook devices for this application? These questions allows you to decide if a chain hoist is the right tool for the job. Depending on the application, different duty cycles, and capacities may be required.

What is the environment the hoist will be used in? (hot, cold, caustic, outside, inside)

• The environment a hoist is being used in is detrimental to the life of the hoist. Hoist have a duty cycle within certain temperature parameters.
• High heat areas can cause the hoist to malfunction, and in many cases cause gearbox leakage.
• Extreme cold temperature can cause casing cracks, and seized components.
•  Extreme changing temperatures can cause condensation in the electrical panel if the wrong hoist is used causing components to short out.
• Is the hoist going to be inside or outside? If the hoist is exposed to the elements of the weather then this will greatly affect the life of the hoist if you don’t have the right hoist.

What is the duty cycle required?

How often will the hoist be running per day?
How long does one cycle of the hoist last during its use?
Many chain hoists cannot dissipate the heat from the motors so the duty cycle is very important to consider prior to purchase.

What is the weight of what you are lifting?

• The weight of what you are lifting is vital to the decision of what type of hoist you invest in.
• Don’t forget to include the weight of any below the hook device that you will be using for this application.
• Pick a hoist with a greater capacity than what you are picking up. Just because you are lifting 500 lbs does not mean you need a 500 lb capacity hoist. The duty cycle will also play an important part in this decision. If you are picking up 500 lbs every pick the hoist will do during its cycle then you should consider getting a larger capacity hoist to reduce wear and tear on your equipment.

Most chain hoist can only go up to 5 ton capacity.Over five tons you should consider a wire rope hoist. Some manufacturers will design a double hoist unit that combines two hoists together and the capacity can be increased to 10 ton, but should only be used in certain applications.

How high do you need to go?

• Remember unlike a wire rope that spools the excess wire rope not being used, the chain hoist has a chain container to catch the excess chain. The greater the height then the bigger the chain container will be. If it is too big it may be an obstruction of what you are lifting if it is required to go close to the hoist.If it is over 30 feet of chain that will be needed then you will also need to think about the duty cycle and speed of the hoist.  There are Windmill Hoist on the market that allows for low capacity, high lifting speeds, with high allowable height of lift.
• The distance from the top hook to the bottom hook when the bottom hook is at it's up-most point needs to be taken into account as well. You will need to ensure you have enough height for your application using that dimension.

What is the voltage available for the hoist?

Higher duty cycle hoist will not run off of single phase voltage. You will need to purchase a three phase hoist so make sure you have enough power in the building for your hoist.

If you are considering purchasing a single phase hoist, make sure it is for a low duty cycle application.

What safety features do I need to be aware of? 

There are many safety features that you should think about having for your hoist. Again the application will be dependent upon what type of safety features you should have for your hoist.

• All chain hoist should be purchased with a load limiter or internal clutch that does not allow for severe overloading. This will be safer for your operators that will help prevent overloading causing severe wear, or even worse someone getting hurt. Overloading is easily preventable.
• Ensure that you have upper and lower limit switches. This prevents the chain from falling out of the hoist or the hoist two-blocking and getting the load stuck or in the air.
• If you have a motorized trolley on the hoist you should think about travel limits. Travel limits will prevent the hoist from slamming into your end stops increasing the life of your hoist.
• Self Adjusting brakes is a great safety feature that also lowers your cost of maintenance
• Motor Thermal Overload features prevents the hoist from overheating

What is the warranty and what does it cover?

Purchasing a hoist out of a catalog because it is economical is not always your best deal. Warranty needs to be considered because it can help you down the road immensely. Don’t just look for a warranty length either. Read the fine print. There are chain hoist manufacturers that will provide you with a lifetime warranty on their equipment. But if you read that fine print, that lifetime warranty only applies to certain components of the hoist, and typically does not include labor to repair it. Find a dealer who is nearby that can easily service the hoist, and pick a hoist that has a solid warranty with labor included. Labor typically will cost you more than the parts so it is very important you look for this.

Once you have answered all these questions you should be able to pick out the hoist that is right for you and will provide the best return on investment. It is a good idea to include your overhead crane service provider to help you with making the right choice in your investment. Don't go it alone, find a provider who is willing to partner with you and provide free consultations on projects no matter how small.