You don’t have to reach far to find the reason so many manufacturing and fabrication companies rely on overhead cranes. These powerhouse contraptions operate smoothly for low operating costs.
Their versatility can make managing a floor easy. It’s also not a stretch to say that overhead cranes make up nearly 1/3 of all cranes used in the industry. Few things can compete with the power and convenience.
Not convinced? Well, let’s take a look at what an overhead crane offers in features that you can take advantage of.
Don’t wait until your floor is clogged and navigation becomes impossible. Get invested in the single greatest floor management equipment around.
Types of Overhead Cranes
To start understanding the benefits of an overhead crane you first need to break down what it is. An overhead crane functions by keeping the boom and lifting apparatus above the work floor.
Two overhead crane types exist: the bridge crane and the gantry crane. Each provides a slightly different set of advantages and utility.
The overhead bridge crane runs across a track which has been elevated. The hook motion can be utilized along multiple axes. These axes give the crane the ability to go up and down, back and forth, and from side to side.
The crane can be mounted either above a girder system or underhung on those girders. The girders provide a lot of stability for lifting loads but obviously restrict the range of motion.
Bridge cranes can’t be moved easily, or really at all without a total re-install. However, they offer maximum stability for the area they are in and can support enormous structures with speed and safety.
Gantry cranes are the slightly smaller of the types of overhead crane. These cranes run on tracks or wheels set on the floor. The crane boom still extends overhead, which gives it the categorization.
Gantry cranes, as they are mobile, can be used in multi-building and external environments and setups.
Supports can be extended from the wheels or the base of the crane to provide added stability when working in an area. The tradeoff in mobility does come at an overall less stable piece of equipment.
Now you understand the differences between the two overhead crane definitions. Next, we can talk about the crane classification system.
The CMAA (Crane Manufacturers Association of America) rates cranes. They use criteria such as how many times the crane starts per hour and the lifted capacity percentage.
- Class A for standby or infrequent service
- Class B for light service
- Class C for moderate service
- Class D for heavy service
- Class E for severe service
- Class F for continuous severe service
Each classification can be used anywhere, but they represent trends in best case utilization. The classifications increase in their necessity for reliability.
The first grouping, class A, covers cranes which sit idle for long periods. These are often operated slowly and only occasionally require a maximum capacity lift.
Class B operates low but consistent frequency. These also need to be slow-paced and sometimes at maximum lift loads.
C and D cranes get the most use across the industry. These provide loads that reach capacity about 50 percent of the time. The C classification covers load averages of up to 10 an hour. The D classification moves up to 20 lifts an hour on average with a lift maximum occurring 65% of use.
Classification E and F require a lot of maintenance costs as they run in near continuous operation. These are expected to be lifting capacity loads 80% for E classification. E will be lifting as many as 25 loads per hour.
At the final F classification capacity is hit at 90% or more. These cranes also are expected to lift as soon as they unload.
Classification F cranes normally feature multiple girders and top-riding bridge cranes. The expectation to operate at peak efficiency can mean trouble. These cranes need to be thoroughly inspected and serviced routinely to prevent accidents.
Safety on the floor when operating a crane starts with understanding the capacity and capabilities of the crane.
A general rule of thumb is also to avoid moving loads over personnel.
A crane operator should know the tolerance of the unit so they know what it can handle safely. They should also be aware of the general weight of any cargo being lifted.
Straps and chains should be used to secure shifting loads or multi-piece load that may move suddenly when starting and stopping.
A whole set of individual guidelines exists for crane safety. The guidelines cover items such as materials being transported as well as the environment of transport.
The single largest danger when operating a crane comes from overloading. However, efforts to get overload protection on cranes has not gone smoothly. This safety feature would prevent the crane from operating when it detects on overly heavy load. Some manufacturers have built this into cranes, but it remains non-standard.
The first step in planning for an overhead crane installation comes down to what type is needed. This question covers how often a crane is needed, where it will be needed, and what support structures exist.
Choosing the right classification and type of crane ensures a solid investment for a company. Making poor or short-sighted decision can cost a lot of money to modify buildings around the crane so the crane can work properly.
Without proper consideration of the install, a crane can be one of the most expensive paperweights in the world.
Don’t install a crane internally and expecting it to be used for lifting and setting loads outside of a radius. This has been a problem for more than one manufacturer that didn’t plan ahead.
Now you understand the value overhead cranes provide to your manufacturing efforts. If you need to know more about what services we provide, check out our about us page.
Contact us for training and inspection services in your area. We can fill you in on specific model details or arrange timelines for testing and inspections.