The first crane appeared in the UK in 1830. It was a steam option. A more advanced model, already hydraulic, was designed after 17 years. But if earlier, when the first lifting cranes appeared, the work was carried out by and large with manual force or partial mechanization, today any construction site, starting from small to large, has at its disposal a construction crane.
A bit of general information
It must be understood that such a device as a construction crane does not exist. There are cranes. This term was coined by Gosgortekhnadzor. The definition was approximately as follows: a crane is a machine that has a load-lifting member (hook, grab, etc.) that is used to lift and move heavy loads.
Today, such equipment is actively used in construction. In principle, from an economic point of view, this is quite profitable. A modern crane can lift a load of more than 1000 tons, but typical 50-toners are suitable for construction.
Duty cycle
It should be understood that for lifting and moving the load, the operator needs to perform simple manipulations (cycles). At the first stage, cargo is captured. If it is a concrete slab, then it is bound, and a hook is used to lift it. If it is bulk material, work is carried out by a grab. The second stage is a working move. It consists in the direct movement, as well as the unloading of the transported material. In fact, this is the most crucial stage, so the work should be performed smoothly and without jerking. The final stage is idle. It implies the return of the lifting device to its original position. By the way, the working stroke consists of three stages: acceleration, steady motion and braking. The first and third stages are the most important, since dynamic loads appear on them and, consequently, the risk of damage to the transported load.
Construction crane and its construction
By and large, the unit consists of several important nodes. Let's look at each of them:
- Metalwork is the basis of a construction crane. All that can be attributed here is spans, supports, arrows, etc. It is worth noting that they are box-type and trellised. In construction, box-shaped metal structures are more often used.
- Lifting mechanism - consists of a flexible lifting body. It can be a rope or chain. The gripping device (loop, grab, hook, etc.) should also be included here. In construction hoisting equipment, hook cranes are most often used.
- The load-gripping body is not automatic (hook or loop), requires minor manual work, as well as automatic (electromagnet or pneumatic suction cup).
As you can see, a construction crane is a rather complicated device that needs constant supervision and replacement of ropes, hooks and other parts and assemblies.
Classification by design and movement
It is immediately worth noting that there is no single classification that would reflect the full essence. The fact is that modern cranes can combine several functions at once. So, there are the following construction cranes, depending on the design:
- Boom - in this case, the load-gripping body is mounted on the boom. It is these cranes that are most often used in construction, since their maneuverability and mobility allows you to perform all the work quickly enough.
- Bridge - metal construction is a bridge to which a load-gripping body is suspended.
- Cable type cranes .
As for the possibility of moving, it makes sense to say only about two main types: stationary and self-lifting. The latter type is just used for the construction of buildings. Its feature is that it is installed on the facility under construction. As the building grows, the crane rises using special mechanisms. Although in recent years mobile jib cranes have been used more and more often, which are in the lead in many respects in terms of technical characteristics. Such a construction crane is adjusted if necessary and can easily be moved to another object. Now let's move on.
Construction tower cranes
Tower cranes are the most rational in civil and industrial construction. This is due to the fact that they allow installation, dismantling and transportation by motor vehicles. This allows to reduce production costs due to the acceleration of work. But sometimes such a crane does not work out due to insufficient space. In this case, a quick-mount tower crane is used. This type of construction hoist is good because it does not need a lot of space to install it. True, such a lifting device cannot be used when the building height is above 30 meters. It is interesting that in one shift the crane can be dismantled and assembled at another construction site with minimal production costs. Today it is one of the most appropriate solutions after truck cranes.
Pneumatic and crawler crane
The option running on a pneumatic-wheeled chassis is good in that it has increased cross-country ability. In principle, such a construction crane, the photo of which you can see, is used in close proximity to the object. This was achieved by installing several steered axles. In addition, the operator's cab is quite comfortable. There is a computer that almost completely eliminates the human factor, air conditioning, etc. of the system.
There is also a crawler crane. It is mounted on a tracked chassis. Despite the high cross-country ability, such equipment is able to work effectively only on pre-prepared sites. Transportation is carried out using a special trailer, which increases operating costs. That is why such construction equipment is not used everywhere. Cranes of this type are used only where any other is not suitable.
Conclusion
So we figured out with you what a construction crane is. You can find photos of several popular models in this article. I would like to note that today such lifting equipment is used everywhere. It allows you to reduce the risk of injury and reduce the amount of manual work. There are a large number of cranes, this applies to both their types and lifting capacity. Some are designed for fast work and mobile movement to another object, while others, on the contrary, lift slowly, but rather heavy loads, and stand on objects for weeks, or even months.