The market situation

In 2011 October, industry of machinery of our country project overall sales downturn trend does not change. Among them, the excavator sales fell 29.92%; the bulldozer sales fell 21.34%.

In 2011, affected by the national macro-control, tightening credit policies led to parts in theconstruction project progress slowed, the original plan started the postponement of some projects started; at the same time consumers affected by the credit crunch policy, purchasecost reduction leads to lower demand of Engineering machinery. Despite the currentconstruction machinery market is facing severe challenges, but China's economic growth momentum remains strong, in the next period of China's construction machinery industry is still in the period of rapid development, especially the crawler crane industry prospects.The adjustment of the industrial structure of national development and Reform Commission promulgated the "Guidance Catalog (2011 version)" clearly pointed out, the 400 tons and above crawler crane as an emerging industry was chosen as "encouraged" products,optimistic about the prospects of crawler crane.

The first three quarters of 2011, China's heavy truck industry total sales of 712000 vehicles. Heavy truck market development is descending into the period:

One is the industry policy in the increasingly stringent, the state promulgated many laws insafety, environmental protection, energy saving etc, also have more stringent trend in the execution of the link. Increase the formulation and implementation of these regulationsforce, will lead to heavy truck industry to improve product technology requirement, at the same time, the product cost will be further improved.

The two is the increasingly fierce market competition. China truck market has been facing the globalization competition pattern, although China's heavy truck industry in the local brand market share occupies a great proportion, but this does not mean that the futurepattern will remain, product technology to improve localization, reduce manufacturing costand other factors, to make the future of heavy truck industry competition environment changes.

With the continuous development of more and more of the crane industry enterprises to join in the crane industry. With high risk points out, engineering machinery including technical risk, economic risk and volatility risk of supply and demand. The core technologyof current construction machinery parts of the product is mainly reflected in the overall design and technical integration, if enterprises can not be timely research and development of new technology, new technology and new products, to meet the requirements of the market, the products may face the risk of being eliminated.

Because of China's construction machinery industry competition is very intense, especially the international construction machinery giant inroads into China's market. Compared with foreign competitors, China's enterprises in the product category, R & D strength,technology level, capital scale and brand influence, there is still a wide gap between. In addition, the world economic fluctuations or will give the industry to bring a certainuncontrollable risk. Engineering machinery industry as a basic construction projectinvestment driven industries, if the economic growth rate slowed down the scale of the future, investment in fixed assets under [1]

2 History

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In 10 BC, the ancient Rome architect Witt Lou Weiss has in its architectural manualsdescribe a hoisting machinery. This machine has a mast, mast top pulley is arranged, fixed mast position by winch cable pull, pull the cable through a pulley, to lift weight. A little overweight machinery available two masts, forming a herringbone, the lift lateral movement,but the magnitude is very small, the operation is very difficult.

To fifteenth Century, Italy invented the jib crane, in order to solve the problem. This kind ofcrane with cantilever root inclined, arm arranged on the top of the pulley, both capable of lifting and rotating. But it was not until eighteenth Century, the use of various humanhoisting machinery also is to human, animal power, in the weight, using range and the work efficiency is limited.

In late eighteenth Century, after the British Watt improvement and invention of the steam engine, to provide dynamic conditions for the heavy lifting machinery. In 1805, Englandbuilt the first steam engineer Lennie overweight machine for the London dock. In 1846,Britain's Armstrong put a steam crane Xin Bao dock is changed into a hydraulic crane.

The beginning of the twentieth Century, Europe began to use the tower crane,

The crane hoisting mechanism, operation mechanism, luffing mechanism, slewing mechanism and metal structure. The hoisting mechanism of the crane, is mostly composed of hanging system and winch, also have through the hydraulic system of lifting heavy objects. The running mechanism is used for the longitudinal horizontal migration of heavy loads or adjust the crane working position, the general is composed of motor, reducer,brake and wheels. At only equipped with luffing jib type crane, jib looked up and when theamplitude decreases, the magnitude of increase is down, balance between the amplitude and the amplitude of the non-equilibrium two. The rotary mechanism is used to make the arm turn, is composed of a driving device and a rotary supporting device. Metal structure is the skeleton of the crane, the main bearing parts such as bridge, arm and door frame for the box structure or truss structure, but also for the web structure, and some can be used as the supporting steel beam. [1]

3 Classification

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In the bridge engineering hoisting machinery used, according to its structure and the performance of different, generally can be divided into light small lifting equipment, bridgetype crane

Hoisting machinery classification

Hoisting machinery classification

And jib type crane, cable crane four categories. A heavy equipments such as: Jack, air hoist, electric hoist, balance hoist (also known as the balance crane, winch etc.). Bridgetype hoisting machinery such as beam type crane etc.. Jib type crane as stationary slewing crane, tower crane, truck crane, cranes, crawler cranes. Cable crane like lifts etc..

According to the lifting properties: mobile cranes, tower cranes, jib crane.