7 Main Parameters For Buying An Overhead Crane
May 23, 2023
7 main parameters for buying an Overhead Crane
In order to purchase a more suitable bridge crane, it is necessary to understand and clarify several of its main technical parameters, including lifting capacity, span, lifting height, operating speed, lifting speed, type of work, and energization duration of the motor.
1. Lifting capacity
The lifting capacity, also known as the rated lifting capacity, refers to the actual maximum lifting load allowed by the crane, in units of tons (t).
The lifting capacity of the bridge crane is 5, 10 (single hook), 15/3, 20/5, 30/5, 50/lO, 75/20, 100/20, 125/20, 150/30, 200/30, 250/30t (double hook), etc. The numerator in the number is the lifting weight of the main hook, and the denominator is the lifting weight of the auxiliary hook. For example, a 15t/3t crane means that the rated lifting capacity of the main hook is 15t, and the rated lifting capacity of the auxiliary hook is 3t.
Bridge cranes can be divided into three grades according to their lifting capacity, 5-10t is a small crane, 10-50t is a medium-sized crane, and more than 50t is a heavy-duty crane.
2. Span
The span of a bridge crane refers to the distance between the centerlines of the wheels at both ends of the main girder of the crane, that is, the distance between the centerlines of the cart tracks, in meters (m).
Bridge crane spans are 10.5, 13.5, 16.5, 19.5, 22.5, 25.5, 28.5, 31.5m and so on. Every 3m is a grade.
3. Lift height
The distance between the upper limit position and the lower limit position of the crane's spreader or grabbing device (such as grab bucket, electromagnetic chuck) is called the lifting height of the crane, in meters (m).
The commonly used lifting heights of cranes are 12, 16, 12/14, 12/18, 16/18, 19/21, 20/22, 21/23, 22/26, 24/26m and so on. Among them, the numerator is the lifting height of the main hook, and the denominator is the lifting height of the auxiliary hook.
4. Running speed
The operating speed refers to the corresponding speed of the large and small trolley moving mechanism when the driving motor is running at the rated speed, and the unit is meter/minute (m/min). The running speed of the trolley is generally 40~60m/min, and the running speed of the large car is generally 100~135m/min.
5. Improve speed
The speed at which the motor of the lifting mechanism makes the weight rise at the rated speed, that is, the lifting speed. Generally, the lifting speed does not exceed 30m/min, which depends on the nature, weight and lifting requirements of the heavy object.
The lifting speed is also available with an empty hook speed, which reduces non-productive time, and which can be up to twice the rated lifting speed.
There is also a special case of the lifting speed. The low speed when the heavy object is close to the ground is called the low landing speed to ensure the safety of the person and the cargo. The speed is generally 4~6 m/min.
6. Type of work
The working type of the crane is determined according to its load rate and work busyness, and can be divided into four types: light, medium, heavy and extra heavy.
(1) Light grade. The running speed is low, the number of times of use is small, the chance of full load is small, and the power-on duration rate is 15%. For workplaces that are not stressful and heavy. For example, it is used as a crane for installation and maintenance in hydropower stations and power plants.
(2) Intermediate. Often work under different loads, the speed is medium, the work is not too heavy, and the power-on duration rate is 25%, such as the cranes used in general machining workshops and assembly workshops.
(3) Heavy grade. The work is heavy, often working under heavy loads, and the power-on duration rate is 40%, such as cranes used in metallurgical and foundry workshops.
(4) Extra heavy class. The rated load is often lifted, the work is particularly busy, and the power-on duration rate is 60%, such as a bridge crane dedicated to metallurgy.
7. Power-on duration
Each motor of the bridge crane works intermittently in a working cycle, and the heavy degree of its work is expressed by the power continuity rate JC%.
