Construction Machine Blog

The crane is a very versatile construction equipment. As I have mention before in my previous posts, there are many types and shapes of cranes in the market such as truck crane and tower crane. Different types of cranes are used on the basis of the amount of weight to be lifted and the area available for movement at the construction site. Today in this article, I want to focus my attention on jib crane, another important member of the crane family. You dear readers would also learn about the various types of Jib cranes in the article.

 Jib Cranes

The design of a Jib Crane

As a common type of cranes, the jib crane consists of a pillar fixed to the wall or mounted on the floor. The pillar supports a horizontal jib, or boom which has a movable hoist. The hoist is used to lift or lower a load with the help of a drum, or lift-wheel, which has a chain or rope wrapped around it. The drum is driven electrically or pneumatically, and can be operated manually. The lifting medium is usually a chain, although it may also be a fiber rope or wire cable. The load is lifted with the help of a lifting hook attached to the lifting medium.

 The design of jib crane

 Types of Jib Crane

As a particular type of cranes, jib cranes can also be divided into several types. The floor mounted type, wall mounted type (fixed) and wall mounted type (traveling) are the three main types. Let’s see them in details one by one.

 Floor Mounted Type

This is the most commonly used Jib crane. Floor mounted jib crane is a self-supporting jib crane having a vertical mast mounted on a concrete foundation. These types of cranes are generally used to share the load of main cranes. The construction of the crane is as described above. All these cranes can rotate 360 degrees and are manually operated.

  Wall mounted type (fixed)

This type of crane is mounted horizontally on the wall and instead of a vertical shaft has a RCC column bracket mounting. The hoist mechanism is similar to the floor mounted type, but without a vertical boom. The RCC column bracket allows a maximum rotation of 200 degrees but covers the area near the bracket mounting without obstruction at floor level.

 Wall mounted type (travelling)

The construction of this type is similar to that of fixed type with the only difference that the crane is able to cover the lengthwise area near the building columns without obstruction at floor level. The crane’s columns are specially designed and the crane instead of rotating, moves along a runway track suspended along building columns.

Through this article, I hope all of you dear readers have a better understanding about cranes and jib cranes.

The crane is a necessary piece of equipment to the modern construction field. A crane tends to cost a large sum of money and its maintenance is also very expensive. Although there are many professional companies have been set up to offer crane maintenance service, their charge is a little bit high. Thus if the crane owner is able to repair the crane by himself, he can surely save a lot of money. As a matter of fact, very body can offer cranes a good maintenance as long as he is familiar with the machine and has some basic knowledge of maintenance.

Crane Maintenance

When a crane gets broken down, the first step we should do, of course, is not to fix it instantly, but to check each part of the equipment to see where the problem lies. It is something a doctor should have a diagnosis on his patient to find out the cause of the disease before he can take any actions. As for the diagnosis of the crane, the following are some details we should pay special attention when inspecting a crane.  

The typical structure of a crane Read more…

Wherever you are in a city, there are lots of things that always keep visible for you. Among them, tower crane is the most common one. Whenever we raise our eyes on the street, we would see many tower cranes swinging in the sky above the city. They are so high and seemingly so dangerous that you cannot ignore them. They are usually used in the construction of tall buildings. What’s more, their height can grow as the building grows taller. As such a heavy equipment, how are the tower cranes able to grow with the growth of the building? For once a while, this question had bothered me. And if you dear readers were confused with the same question, then reading the post will dispel all your suspicions.

Tower cranes arrive at the construction site on 10 to 12 tractor-trailer rigs. The crew uses a mobile crane to assemble the jib and the machinery section, and places these horizontal members on a 40-foot (12-m) mast that consists of two mast sections. The mobile crane then adds the counterweights.

The mast rises from this firm foundation. The mast is a large, triangulated lattice structure, typically 10 feet (3.2 meters) square. The triangulated structure gives the mast the strength to remain upright.

To rise to its maximum height, the crane grows itself one mast section at a time! The crew uses a top climber or climbing frame that fits between the slewing unit and the top of the mast. Here’s the process:

1. The crew hangs a weight on the jib to balance the counterweight.
2. The crew detaches the slewing unit from the top of the mast. Large hydraulic arms in the top climber push the slewing unit up 20 feet (6 m).
3. The crane operator uses the crane to lift another 20-foot mast section into the gap opened by the climbing frame. Once bolted in place, the crane is 20 feet taller!
   

 You dear readers may be also wandering how the tower crane comes down when a building is finished. As long as you have understood the above steps, the question is naturally solved, because the process is reversed — the crane disassembles its own mast and then smaller cranes disassemble the rest. As we can see, the whole process are actually not confusing at all, although a little bit complicated indeed.

The tower crane is a modern construction equipment, which is frequently used in the construction of tall buildings or long bridges. Although we happen to see a tower crane from one time to another, most of us have never looked them closely. What is its structure? Which parts it include? And what the respective function of each part? This post is going to shed some light on these questions.

Tower Crane And Its Parts

Although there are various tower cranes of different types and models on the market, the basic physical structure is the same for all of them. Tower cranes, regardless of their types and models, are assembled by such mechanic parts as jib, rigger and so on. The following are details about these parts, including their pictures. I hope this can help you dear readers better understand what a tower crane really is.

Here are some basic parts of tower cranes

The base is bolted to a large concrete pad that supports the crane.

The base connects to the mast (or tower), which gives the tower crane its height.

Attached to the top of the mast is the slewing unit — the gear and motor — that allows the crane to rotate

On top of the slewing unit are three parts:

The long horizontal jib (or working arm), which is the portion of the crane that carries the load. A trolley runs along the jib to move the load in and out from the crane’s center:

 The shorter horizontal machinery arm, which contains the crane’s motors and electronics as well as the large concrete counter weights:

 The operator’s cab:

 The machinery arm contains the motor that lifts the load, along with the control electronics that drive it and the cable drum, as shown here:

 The motors that drive the slewing unit are located above the unit’s large gear: