Selection of tower crane

Contents

Design Task ________________________________________

Description of tower crane and principle of its operation _____________________

Construction of crane load characteristic __________________________

Selection of crane lifting mechanism rope __________ __________

Selection of crane lifting mechanism motor _______ __________

Description of safety precautions during operation of cranes _____________

Conclusion of the _____________________________________________ _______

List of literature ______________________________________________

2. Description of tower crane and principle of its operation

A tower crane is a lifting machine with an boom fixed in the upper part of the vertical tower and performing work on the movement and installation of structures... [1]

The main purpose of the tower crane is to serve the territory of construction sites of buildings and structures, warehouses, landfills, loading and unloading of materials from transport - during construction, installation and loading and unloading [2], [3]. At the same time, the tower crane makes working movements: changing the departure, lifting the boom, turning and moving the crane. [3] Changing the departure of the boom, depending on its type, is carried out either by lifting or lowering the boom, or moving the cargo trolley along the boom [2]. Cargo lifting is carried out using a cargo winch, a cargo rope and a hook cage. Rotary part of crane is rotated relatively non-rotating by means of rotary mechanism. They are connected by a support-turning device (abbreviated by the OMP), which transmits vertical and tipping loads from the turning part to a non-turning - running frame [3]. The main mechanisms of tower cranes are equipped with special safety devices called limiters, which are equipped with: a mechanism for lifting cargo, turning the crane, moving a freight trolley and lifting a boom. Control of these crane mechanisms is performed by crane operator from control cockpit [2], which, as a rule, is installed in upper part of tower structure [3].

Types and parameters of tower cranes are determined by their technological purpose. Parameters of tower cranes are regulated by GOST. The main parameter of the tower crane is the load capacity, i.e. the largest weight of the load at the corresponding departure. Since the lifting capacity of boom cranes is variable, it is characterized by a load moment. The main parameters include minimum and maximum flight, lifting height and depth of hook lowering, speeds of working movements, dimensions, crane weight, power indices and support loads. Each basic crane model or its design is provided with a cargo altitude characteristic representing the dependence of the lifting capacity on the lifting and departure height used when selecting the crane or its equipment during operation. [1]

Any tower crane consists of the following parts:

1. Tower;

2. Working boom;

3. Support part;

4. Support-turning device;

5. Control cabin.

To perform the main operations, the crane is equipped with the appropriate mechanisms: winches, blocks and polysuppasts [2].

The general-purpose crane tower has either a telescopic design or a lattice, of two types: rotary and non-rotating. At high height, it can be enlarged (from above) and grown (from below). Hook suspension is used as the main load-gripping element. Such cranes, in the bulk, are manufactured in a mobile design on a rail bed, and their design allows for their quick installation and dismantling and further transportation to another object [4].

Cranes for high-rise construction are made in addition. The structure of such a crane rests on the ground and on the framework of the building under construction [4] (using braces) [5].

Cranes for high-rise construction also include self-lifting cranes, sometimes called creeping [4]. The crane of this type is installed on the structures of the building under construction, and then, using its own mechanisms, periodically moves vertically up (one or more floors) - as the building under construction grows [6]. In the monolithic buildings under construction, the self-lifting crane rests on special windows provided in the walls of elevator shafts. When erecting prefabricated reinforced concrete buildings, the support for the crane is the cells (metal or reinforced concrete) of the building frame [7]. The crane can be lifted by a winch located at the base of the tower, or by a special hydraulic extension mechanism. The advantages of this type of tower cranes are: the ability to work on slopes and in cramped conditions, as well as the ability to provide the construction of a building with a complex configuration (in plan) with one crane [7]. One of the main limitations of such a crane (in height) is the rope capacity of the winch, and the main drawback is the difficulty of dismantling after completion of construction. Cranes-loaders are made on the basis and using units of general-purpose cranes [8].