Four rope Overhead crane grab

Four rope Overhead crane grab
Grab bucket is a bucket that can be opened and closed by grabbing sediment and various bulk goods. It is a kind of sling that mainly relies on the opening and closing of two combined buckets or multiple jaw plates to grasp and unload bulk materials. The grab relies on the opening and closing of the left and right combination buckets or multiple jaw plates to grab and unload bulk materials. The grab composed of multiple jaw plates is also called grab claw
Classification by driving mode
According to the driving mode, it can be divided into hydraulic grab and mechanical grab
1、 Hydraulic grab
The hydraulic grab itself is equipped with an opening and closing structure, which is generally driven by a hydraulic cylinder. The hydraulic grab composed of multiple jaw plates is also called a hydraulic claw. Hydraulic grab is widely used in hydraulic equipment, such as hydraulic excavator, hydraulic lifting tower, etc.
Hydraulic grab is a product of hydraulic structural parts, which is composed of hydraulic oil cylinder, bucket (jaw plate), connecting column, bucket ear plate, bucket ear sleeve, bucket tooth, tooth seat and other parts. Therefore, welding is the key manufacturing process of hydraulic grab, and the welding quality directly affects the structural strength and service life of hydraulic grab. In addition, the hydraulic cylinder is also a key driving component.
Hydraulic grab is an industrial equipment accessory, which requires equipment to operate with high quality, such as CNC plasma cutting machine, groove milling machine, plate bending machine, welding positioner, boring machine, hydraulic test bench, etc.
The hydraulic grab for excavator is divided into rotary and non rotary. The grab without rotary adopts the oil circuit of excavator bucket oil cylinder, without adding additional hydraulic valve blocks and pipelines; A set of hydraulic valve blocks and pipelines shall be added to control the grab with rotation.
Hydraulic grab for excavator applicable occasions:
1. Foundation pit excavation, deep pit excavation and loading of mud, sand, coal and gravel of building foundation.
2. It is especially suitable for excavation and loading on one side of the ditch or restricted space.
3. It is applicable to the loading and unloading of ships, trains and automobiles.
2、 Mechanical grab
Mechanical grab has no opening and closing structure, and is usually driven by external force of rope or connecting rod. According to the operating characteristics, it can be divided into double rope grab and single rope grab, and double rope grab is commonly used.
The double rope grab has a support rope and an opening and closing rope, which are wound on the drum of the support mechanism and the opening and closing mechanism respectively. Figure 1 shows the working process of the double rope grab: a means that the support rope and the opening and closing rope descend at the same time, and open the bucket mouth to insert the pile. B to tighten the opening and closing rope, the jaw plate closes and grabs the material. C means that the support rope and the opening and closing rope rise at the same time after the grab is closed. D. in order to keep the support rope stationary, the opening and closing rope drops, the bucket mouth opens and the material is unloaded. The double rope grab has the advantages of reliable operation, simple operation, high productivity and wide application. After using two groups of double ropes, it becomes a four rope grab, and the working process is the same as that of the double rope grab.
The single rope grab support rope and the opening and closing rope use the same steel wire rope. The special locking device enables the steel wire rope to support and open and close in turn. The winding mechanism of single rope grab is relatively simple, but its productivity is low, and it is rarely used in a large number of loading and unloading operations.
According to the bulk density of the material to be grabbed, the grab can be divided into light (such as grabbing grain), medium (such as grabbing gravel) and heavy (such as grabbing iron ore); According to the number of jaw plates, it is divided into double jaw plate grab and multi jaw plate grab, and double jaw plate grab is commonly used. For large ore, scrap iron and scrap steel, it is suitable to use a multi jaw grab, because it has the characteristics of multi claws and sharp cuts, and is easy to insert into the pile, which can get a better grasp effect. There is also a scissor grab (Fig. 2), which imitates the scissor structure principle. Its grasping force can gradually increase with the closure of the jaw plate, reaching a large value at the end of closure; The opening of the bucket mouth and the area covered by the material are also larger than the general grab, which improves the grasping ability and is conducive to cleaning the stockyard and cabin. However, for large materials, the effect is poor because of its small initial grasping force.