How To Choose The Rated Lifting Capacity Of The Crane?

How to Choose The Rated Lifting Capacity Of The Crane?

 

 

Rated lifting capacity

 

5 ton bridge crane The maximum mass that can be lifted once when it is working normally is called the rated lifting capacity, and the unit is ton (T) or dry gram (KG).

 

The rated lifting capacity of the hook crane includes the dead weight of the hook and movable pulley block.

 

The quality of the pick-up devices that can be removed from the crane, such as grabs and electromagnets, is included in the rated lifting capacity, and the rated lifting capacity of bridge type cranes is a fixed value.

 

Among the bridge type cranes, the rated lifting capacity of some cranes is a fixed value, which has nothing to do with the amplitude (such as portal cranes, some tower cranes), and some cranes have different rated lifting capacity corresponding to different jib lengths and amplitudes ( such as tire and truck cranes, crawler cranes, railway cranes).

 

When there is more than one rated lifting capacity, the rated lifting capacity is usually called the maximum lifting capacity, or the lifting capacity for short.

 

The lifting capacity of a crane for lifting bulky items is determined by the maximum mass of the item being lifted at one time (in individual cases, two cranes can be used to lift bulky items).

 

Cranes for loading and unloading bulk materials, the lifting capacity is determined according to the required production rate.

 

For example, the given productivity of the grab crane is P(t/h), and the number of operating cycles per hour of the crane is n.

(It is related to the distance of goods transported, the working speed of the mechanism, the coincidence of the movement of the mechanism, the technical level of the workers, etc.), the weight of the material grabbed each time (the effective volume of the grab * the material capacity) is Q1, and the self-weight of the grab is G, then The lifting capacity of the crane is:

 

Q=Q1+G=P/n+G

 

The ratio of the self-weight of the grab to the quality of the grabbed material increases as the volume of the grab decreases. In order to improve the working efficiency, the crane with large lifting capacity is generally equipped with a main hoisting mechanism and an auxiliary hoisting mechanism. The main hoist has a large lifting weight and low speed; the auxiliary hoist has a small lifting weight and high speed. The lifting weight of the auxiliary lift is determined by the operation requirements. The lifting weight of the auxiliary lifting of the bridge type crane is generally 1/5~1/3 of the main lifting.

 

The rated lifting capacity of truck cranes and railway cranes varies with the orientation of the boom (the three basic operating orientations of side, rear, and front; railway cranes also have a specific orientation that forms a certain angle with the direction of the line); tire cranes The rated lifting capacity of railway cranes can also be divided into three situations: fully extended legs, no outriggers and hoisting.

 

When the crane is hoisting and driving, the boom must be in front. The rated lifting capacity of the crane when working without outriggers and hoisting is determined by the carrying capacity of the tires, axles (or wheelset bogies).

 

 

Span

 

The horizontal distance between the centerlines of the 5 ton bridge crane running track is called the span.

 

The span of the crane mainly depends on the width of the service space, and the span of the crane used in the workshop depends on the width of the building.

 

In order to serialize the span parameters, the commonly used spans of bridge cranes are graded every 3m, and cranes with a lifting capacity of less than 50t have two span values corresponding to each plant span, and there is a safe passage on the crane beam above the plant Use a small value below.

 

If there are cranes above 80 t and cranes below 50 t on the same track, the span of the crane is selected according to the crane above 80 t.

 

Lifting height

 

The lifting height generally refers to the calculation from the ground of the work site (the crane is not supported on the ground track) or from the top surface of the crane's ground running track (the crane is supported on the ground track) to the upper limit of the pick-up device. The vertical distance between locations.

 

When the sling is a hook, take the lower end of the inner arc of the hook ring; when the sling is a grab bucket or other pick-up device, take its lowest point; when the sling is a fork, take the upper surface of the fork.

 

For the crane whose pick-up device is to be lowered to the ground or below the surface of the ground running track, the depth at which the spreader falls to the ground or below the ground running track is the descending depth.

 

The total lifting height is the sum of the lifting height and the descending depth.

 

The symbol of lifting height is H, and the unit is m.