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The Workable Components of an Overhead Traveling Crane

Overhead Traveling Crane | Workstation Crane System

An overhead traveling crane, also known as a bridge crane, is commonly used for industrial load lifting. Overhead traveling cranes can be classified as electric overhead traveling (EOT) crane or a rotary overhead crane. The electric overhead is the more typical of the two and mostly found in factories. They are fully electrically operated by a control pendant, radio/IR remote or from a cabin attached to the crane itself. Rotary overhead cranes are another type of overhead crane, which has one end of its bridge mounted, which is on a fixed pivot, while the other end is sustained on an annular track.

The basic types of overhead traveling cranes can include top running cranes, under running cranes, single girder bridge cranes and double girder bridge cranes. Overhead traveling cranes are generally engineered in four common configurations. You will find on overhead cranes that they have a highly detailed control system, which is specific to performing day to day tasks with the overhead crane. The controls on an overhead traveling crane are the crane pendant, variable frequency drive(VFD), radio remote control, power supply, enclosures, also NEMA 1, 12 and 4.

Controlling the Overhead Traveling Crane

Typically, the pendant is mounted in two ways and can be mounted to a sliding track system. The pendant can also be mounted to the electric trolley hoist itself. When mounted to the electric trolley hoist, there will have to be an operator beside it to move and operate the equipment to move the loads that need to move. The pendant is engineered to perform certain functions of the crane that is intended to be controlled manually. The pendant will control each function and configuration from the bridge travel, trolley direction, and lift speed. Not limited to these functions and configurations the pendant can do much more.

Variable frequency drive is used solely to control the motors of the crane. When controlling the motors this will be done by a varying frequency. The ability to set custom speed and let the equipment accelerate and decelerate smoothly will be dependent on the varying frequency of the motors. Pendant pushbuttons have two different speed controls similarly used with the variable frequency drive. One button maintains the speed and the other can be used to accelerate. The crane will start to decelerate when it’s controlled by the dynamic braking system that is programmable into the variable frequency drive. Radio remote controls can function wirelessly, but uses radio frequency and will not be directly wired into the crane.

Radio Control Safety

The radio controls have various safety features, that will allow the operator to work safely at a distance. Also, multiple cranes can be controlled at once with the same radio remote control. The power supply is the electrical service available in the building, which the crane or material handling equipment is being manufactured will operate from. Enclosures can be gauged for certain varied applications and environments, as they protect other electrical components and also they have three important levels of protection. NEMA 1; the enclosure keeps service crew and operates safe from electrical components and avert them from being electrocuted.

NEMA 12, Has the same functions but keeps oil, dirt, water, dust and other debris out of the internal electrical components. Lastly, NEMA 4, which can be used in indoor and outdoor can protect the enclosure from leaking if it gets extremely wet while offering a greater level of protection from things such as, oil, dirt, water and dust. These controls are highly needed and play a crucial part in the way an overhead traveling crane will function.

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How Do EOT Cranes Increase Efficiency?

EOT Cranes | Electric Overhead Traveling Crane | Overhead Shop Crane Functions

Many people only see cranes as they are driving past the construction sites of new buildings. These cranes are large pieces of machinery and can be anywhere from twenty to fifty feet tall or taller. An operator, trained in the safe driving and usage of EOT cranes, is required to use one of these cranes. However, there are a variety of other cranes , one of these is the E.O.T. crane or electric overhead traveling crane.

The EOT crane is a very popular crane for use in industrial buildings such as warehouses and assembly shops. These cranes are usually sizeable in nature in and consist of large metal bars installed towards the ceiling with hooks or other means of picking up objects. Often these cranes are used when there is a need to move large or heavy objects. If the items that require transport are smaller, a monorail crane is more likely to be used.

EOT Cranes | Licensed Operator

These cranes are operated by a control panel. Unlike some cranes which require a trained and licensed operator, these cranes can be used by any worker who has had basic instruction in their safety operation.

Many cranes can be rented for short term usage. EOT cranes can do a variety of jobs and are a large investment so they are often custom designed for the specific purposes they are intended for and purchased rather than rented. A warehouse assembling cars will use the crane in a different way than a construction company working on a nuclear power plant.

EOT cranes may be used in conjunction with other types of cranes such as monorail cranes or jib cranes. For example, an electric overhead traveling crane may be used to move a large piece of equipment from place to place in the warehouse and the smaller monorail and jib cranes may be used to move smaller components of the equipment to the workstation for assembly.

Smaller EOT Cranes | Jobs

Some smaller electric overhead traveling cranes may even be set up to assist in jobs like cabinet work, lifting heavy granite counter tops into position. While some of the smallest jobs performed by these cranes could be done by a worker or team of workers, the time and potential for serious injury from repetitive heavy lifting make the needed investment a worthwhile one for all but the smallest shops.

Besides size, there are some other differences among electric overhead traveling cranes. They may be single girder or double girder. Double girder cranes have the hoist between two parallel bars. Single girder cranes are generally a cheaper option; however, a study of the weight capacity is needed to determine whether a single or double girder cranes is the best choice for a given application.

A double girder crane can be designed for areas that have limited headroom. These are called ultra-low headroom cranes. This is an important consideration for tight confines and may allow a crane to be used where other types would be impractical.

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Design Elements of Single Girder EOT Cranes

Single Girder Cranes | Industrial Cranes | Industrial Crane Manufacturer

The single girder cranes are a type of electric overhead traveling crane. These cranes are typically utilized in a warehouse environment for the lifting of moderately heavy to extremely heavy objects. Single girder cranes are often an integral part of assembly work, easing the burden on workers and lifting the same amount of weight that would have previously taken a large team of employee’s significant effort and time to move. Such efficiency allows the mass production that defines modern economies.

Electric overhead traveling cranes follow the same general design with some variation between the double girder and single girder models. Double girder models are built with the hoist held in between two large metal beams, typically connected to the ceiling. Sometimes these are built as free standing, lightweight cranes for smaller lifting jobs.

Single Girder Cranes | Design Features

A single girder crane is designed a bit differently. Unlike the double girder crane, the single girder cranes have one beam below which the hoist is connected. Single girder cranes tend to be less expensive than double girder cranes. Depending on the environment they are used,  single girder cranes can be a great choice. Because of their design, the cost for a single girder crane can become high if they need to span very long distances. For shorter distances, these cranes are capable of lifting heavy loads.

Another aspect of single girder cranes to consider is how high the crane can lift the object off of the ground. In some situations, this will not matter, however in others it is imperative that you have a higher lift height. As a rule, single girder cranes are not able to lift objects as high as double girder cranes. This is due to the fact that single girder cranes have the hoist hanging below the singular beam whereas double girder cranes are able to suspend the hoist between the two beams, allowing for extra lift height. In fact, some double girder cranes are designed to be ultra-low headroom cranes that will function in areas that other cranes simply could not fit.

Single girder cranes are generally relatively simple to operate, owing to the fact that they are typically traveling in a straight line on a controlled tracked. Buttons on a control panel allow a worker to initiate the crane and determine the direction of movement.

A single girder crane is an expensive investment and careful consideration of the current and future needs of the business will ensure that the initial cost of purchasing a crane is well worth it. It may be tempting to think that a single girder crane can be used in place of a double girder crane to save money. While this may be the case, single girder cranes only save so much. The design of single girder cranes requires very strong steel to allow for saving and efficient lifting. If a single girder crane meets your needs, then it can be an invaluable tool. If your needs are better served by a double girder crane, then the slightly higher cost is likely going to be well worth it down the road.

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What Is An Electric Overhead Traveling Crane Anyway?

EOT Cranes | Electric Overhead Traveling Crane | Overhead Shop Crane Functions

The abbreviation EOT stands for electric overhead traveling crane. Even though it has the word electric in its name, it can be operated manually as well. It is for the purpose of moving around specified amounts of weight within a limited area. These are used for handling the weight as well. They are very common in many workplaces which require the moving of load. These areas may either be large factories, research facility centers and production plants as well. It has a major requirement in industries where it is common that there is heavy material which needs to be lifted.

Electric Overhead Traveling Crane | Details

Talking about its structure, we can understand how it can lift heavy loads. It has a traveling bridge involved in spanning of the gap, which is connected to parallel runways. The traveling bridge also has a hoist which basically travels on the bridge. The electric overhead traveling crane has a three step working mechanism. In the first step, the hoist is driven by the motor, which generates power. This power is sent over to the reducer in its high speed shaft area, which after processing it, sends it to the reducer to reduce the power to the required amount, and then output is received from the low speed shaft of reducer. This is how the objects are lifted.

In the second step, the trolley’s crane is driven with power by the motor. The power is again sent to the reducer’s high speed shaft, from where it goes to the reducer again after being processed. The reducer reduces the power to required amount and output is received though the low speed shaft of the reducer. Then, through the half gear joint with the trolley. This is how the materials and objects are driven on the crane in lateral position.

Lastly, the trolleys’ crane is driven again by the motor. Just like as in the second step, power is sent to the reducer; from there it is processed by half gear coupling and sent back to the reducer. The reducer again lowers the power of the motor to the required level and the output is received by the low speed shaft of the reducer. Here’s the difference between the second and the third step. In the third step, after the output is received by the reducer’s low speed shaft, it is then received by the full gear coupling joint. In this way, the wheels of the crane move and transportation of the materials is achieved.

Double Girder Overhead Traveling Crane

These cranes have two different models. The single girder electric overhead traveling cranes and the double girder overhead traveling cranes! Whenever there isn’t a heavy load to be lifted, the single girder electric overhead traveling crane is used. Whereas for the process of lifting heavy objects and materials, the double girder is perfect! The reason is that a single girder EOT doesn’t have enough power and space to carry a lot of material and any material that is heavy since it only has a single girder. It has it’s applications in lightweight lifting work. Although it does have the ability to lift less than a hundred kilogram of load and a maximum load of a few tones. The double girder Electric Overhead Traveling crane can definitely lift a lot more and a lot heavier materials. They have the double girder which helps spread the weight of the load evenly on the machine allowing it to lift more weight.