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    What are the classifications of cranes? What are the main problems of selecting cranes?

    Source: Release time: 2019/6/27 9:37:00

        Crane It refers to the lifting machine with vertical lifting and horizontal lifting of heavy loads within a certain range. Also known as cranes. It belongs to material handling machinery. The working characteristic of a crane is to do intermittent movement, that is, the corresponding mechanism of the action of fetching, transporting, unloading and so on in a working cycle is alternately working, and the crane's development and use in the market is more and more extensive. What are the classifications of cranes? How to choose a crane? What are the main problems of selecting cranes?

    Crane (Crane) is a kind of lifting machinery, it is a kind of machinery that circulate and intermittently move. A work cycle includes: picking up the device to lift the object from the place, then moving it to the specified place to drop the object, then reverse movement, so that the fetching device is returned to the original position for the next cycle.

    Usually lifting machinery is made up of lifting mechanism (up and down movement of goods), operation mechanism (lifting crane movement), luffing mechanism and slewing mechanism (horizontal movement of goods), plus metal mechanism, power plant, operation control and necessary auxiliary devices.


    Mobile crane classification:

    1. Truck crane

    The crane is installed on the general or special vehicle chassis with low disk performance equivalent to the same vehicle gross weight, which meets the technical requirements of highway vehicles and therefore can be used unimpeded on all kinds of highways. This kind of crane usually has two control rooms on and off, so it is necessary to extend the outrigger to maintain stability during operation. The range of lifting weight is very large, from 8 tons to 1000 tons, and the axle number of chassis can be from 2~10. It is the largest and most widely used crane type.

    2. Tyre crane

    The crane is mounted on a special pneumatic tire chassis. Up and down with an engine, the speed is generally not more than 30KM/H, the width of the vehicle is also wide, so it is not suitable for long-distance driving on the highway. The utility model has the functions of lifting and driving without lifting legs, and is suitable for lifting operations in places with limited moving distance, such as freight yards, wharves, construction sites, etc.

    3. Cross country tire crane

    It is a crane developed in 70s. Its lifting function is similar to that of a tire crane, and it can also be carried without lifting legs and lifting weights. The difference is the structural form of the chassis and the improvement of driving performance caused by the unique chassis structure. The engine of the crane is mounted on the chassis, and the chassis has two axles and four large diameter cross-country tread tyres. The four wheels are driving wheels and steering wheels. When moving positions on muddy uneven sites, the four wheels transmit power, that is, four wheel drive, to improve the ability to pass muddy ground and uneven road surface. When driving on a flat road at a relatively fast speed, only two wheels are driven by the front axle or rear axle to reduce energy consumption. In the random document of the crane, the four wheel drive is represented by 4 x 4, and 4 * 2 indicates that two wheels of 4 axles are driving wheels. The model is suitable for small field operations. Continuous infinitely variable speed can be realized, and the engine will not extinguish when the road resistance suddenly changes, so that the driver's operation is greatly facilitated. The off-road tire crane is a powerful, flexible tire crane with extended performance.

    4. All terrain crane

    It is a high performance product featuring both truck cranes and off-road cranes. It can be used as a truck crane for fast transfer and long distance running, and also can meet the requirements of narrow and rough or muddy fields. It has the following three steering modes: fast running speed, multi bridge driving, all wheel steering, large clearance from ground, high climbing ability, no lifting function such as leg lifting, and so on. It is a promising product. But the price is higher, and the level of use and maintenance is higher.

    5. Special crane

    A special crane developed for completing a specific task. For example: for mechanized troops to implement tactical and technical support, mounted on off-road vehicles or armored vehicles on the lifting wheel rescue vehicles; for dealing with traffic accidents, such as road wrecker vehicles.


    Crane type selection

    1) material loading and unloading, sporadic lifting and construction operations requiring quick entry. The choice of truck cranes is more appropriate. If the truck cranes with telescopic boom and outrigger can be retractable are more favorable, hydraulic truck cranes are ideal hoisting machinery for extending telescopic arms into windows or openings.

    2) when lifting works require heavy lifting, high installation height and large amplitude lifting operations, crawler or tyre cranes can be selected according to existing mechanical conditions. If the ground is soft and the driving conditions are poor, the crawler crane is the most suitable; if the ground is not allowed to be damaged within the scope of operation, the tires are the best.

    3) when the construction conditions are limited, it is dangerous to crane the crane when the crane is hoisted. If the crane is not allowed to operate, the lifting weight should be in accordance with the instructions of the machine, and the crawler or tyre crane can be selected. The performance of the wheel crane is better, and the stability of the crawler crane is higher.

    4) professional cranes should be chosen as professionally as possible. For short distance handling of sporadic goods, a truck mounted crane (YD type) can be used, which originally needs lifting and transporting two mechanical operations. Now it can be completed by one.

    5) try to choose a multi purpose, efficient and energy-efficient crane product. For example, when the construction site needs to be hoisted by itself, and when using tower cranes, a self lifting tower crane with cranes should be selected to save the number of inputs.


    Crane type selection

    According to the lifting capacity and lifting height, taking into account other conditions on the site, the appropriate specifications can be found from the sample or technical performance table of the mobile crane. The greater the maximum lifting capacity of a crane, the more difficult it is to make full use of its performance in hoisting projects, and the lower utilization rate. Therefore, as long as the hoisting technical requirements can be met, it is not necessary to choose an oversized model.

    It must be pointed out that the nominal lifting capacity of a crane is the allowable lifting weight at the shortest and the minimum amplitude of the boom. When the boom is extended, the weight of the crane decreases correspondingly, and its value can be calculated from the crane performance data. When the tires are unable to use the outrigger, the lifting capacity shall be calculated according to the specified performance or according to the instruction manual (generally less than 25% of the weight of the leg). If the crane is hoist on the flat and hard road, the lifting weight shall be 75% of the rated capacity without lifting the leg, so as to ensure safe operation.

    If the lifting capacity of a single crane can not meet the requirements, two units can be selected for lifting construction. To ensure construction safety, the weight of the lifting component can not exceed 80% of the total lifting capacity of the two cranes.

    Selection of crane economic performance

    The principle of comprehensive economic performance criteria for self propelled cranes is to minimize the unit price of materials or components in transportation, hoisting and loading and unloading. Therefore, the unit price of material transportation can be calculated by the lifting capacity (or the productivity stipulated in the rental contract) and the cost of the class shift (or the cost stipulated in the rental contract), and then the lowest one is selected. In addition, we should consider the products with less energy consumption and more functions, so as to reduce the intensity of artificial labor. In short, from technically feasible self propelled cranes, it is possible to provide the most effective and efficient models and specifications at present and in the future.