2.2.1 Tackle
1.Basic Structure and Function of Tackles
(1)Basic structure
The tackle is mainly composed of hooks(links),pulleys,shafts,bushings(or bearings)and clamp plates,as shown in Fig.2-20.
Fig.2-20 Sample of Tackle Structure
(2)Basic function
The tackle is one of the commonly used tools for power line maintenance and construction and installation.It can generate a rotary motion by means of a hoisting rope,thereby changing the direction of the force.Because the tackle is easy to use and carry,it is widely used in line maintenance and construction and installation.
2.Classification and Technical Parameters of Tackles
(1)Classification
①According to the material,it can be divided into iron tackle,aluminum tackle,stainless steel tackle and insulated tackle.
②According to the use,it can be divided into lifting tackle,tackle for paying-off,and somersault tackle.The lifting tackle is divided into a ring type lifting tackle,a hook type lifting tackle,a hanger type lifting tackle,and a chain ring lifting tackle;the tackle for paying-off is divided into a ground cable pulley,a cable pulley,a skyward pulley,a nylon pulley,a cable conductor paying-off pulley,a large diameter tackle for paying-off,and a lifting pulley.
③According to the number of sheaves of the tackle,it can be divided into a single-sheave tackle,a double-sheave tackle and a multi-sheave tackle.
(2)Technical Parameters
①Naming method for the model of the tackle
Model specifications of H series tackles are represented by a set of text codes,and the code consists of 4 parts.
②Model code of the tackle
The type code of the tackle is shown in Table 2-6.
Table 2-6 Type Code of the Tackle
③Selection of tackles
When selecting the tackles,according to the lifting mass and the number of pulleys required,check the diameter of the bottom of the sheave groove of the tackle and the diameter of the wire rope used in accordance with Table 2-7 to check whether the selected wire rope meets the requirements.
Table 2-7 H-Type Tackle Selection Table
Table(Cont'd)
3.Inspection Items of Tackles
The tackle must be inspected before use as follows.
(1)Visual inspection must be carried out before use.Where any hooks,rings,guard plates,partitions,etc.have severe deformation and cracks,rims are broken,bearings are deformed,bearing bushes are worn and rotation is inflexible,parts are incomplete,and tonnage is unclear,they shall not be used.(https://www.daowen.com)
(2)Check if the torsional deformation of the lifting ring,the misalignment of the hinge plate,and the radial wear of the sheave groove and the uneven wear of the sheave groove affect the use.
(3)Check the appearance of the tackle for defects such as cracks and breakage.
(4)The test certificate of tackle shall be checked for its validity.
(5)Mainly check whether the pulley of the tackle and the lifting ring are flexible,whether there is jamming phenomenon,whether the opening and closing hinges and the clamp plate are flexible.
4.Usage of Tackles
(1)It shall be safely used according to the factory nameplate and shall not be overloaded.
(2)To use the open-door tackle,the door holder must be locked.
(3)During the loading and unloading process,the tackle must not be thrown to prevent deformation of the components.
(4)The commonly used multi-sheave tackles are all of the opening type,and the connecting part includes a rotatable lifting ring type and a fixed lifting ring type,and the tackle of the fixed lifting ring has a directionality when it is suspended.The tackle is not allowed to bear the torsion when force is applied,otherwise it shall be adjusted by adding a U-ring.
(5)If the direction of the force changes greatly or when the tackle is used in a high place,a ring-type tackle shall be used.If a lifting hook-type tackle is used,the lifting hook opening must be sealed.The hook-type hook is easily decoupled from the binding rope after repeated stress.
(6)When the hook or the tackle hook is used,the sealing plate shall be installed.If the sealing plate is damaged or lost,use the#10 iron wire to seal the hook.Do not tie the binding rope to the hook with the iron wire,as shown in Fig.2-21.
(7)In order to prevent the hook or the lifting ring of the single-sheave tackle from rotating with the tackle block during the stress process,so that the hauling rope is twisted,the hook or the lifting ring is fastened to the guard plate by using the#8 iron wire,as shown in Fig.2-22.
(8)The tackle block is composed of single or multi-sheave single-whip tackle and movable tackle.When using,the size and model of the two tackles shall be basically the same.It is not suitable to use the tackles of different sizes to form the tackle block.
Fig.2-21 Specifications for Use of Iron Tackle(I)
(a)Correct;(b)Incorrect
Fig.2-22 Specifications for Use of Iron Tackle(II)
(a)Correct;(b)Incorrect
(9)The method of stringing the tackle block includes two types:the ordinary winding method and the flower winding method.Generally,the ordinary winding method is adopted.It is to fix two tackles(single or multiple sheaves)on the ground at an appropriate distance,and wind the wire rope ends from the sheave groove on one side of the tackle,and then wind it into another corresponding sheave groove.In the same direction of winding,it is wound up to the last sheave groove.After the wire rope is inserted and when it is tightened,the strands shall be parallel to each other and must not be twisted and displaced.
5.Precautions for Storage of Tackles
(1)The tackles shall be stored in a well-ventilated and dry environment,and put on shelves.Fig.2-23 shows the placement of the iron tackle on the shelf.
(2)When the tackle is not used for a long time,it shall be cleaned and coated with anti-rust oil to avoid rust.Each group of tackles shall be numbered.
Fig.2-23 Placement of Iron Tackle on Shelf
6.Requirements for Inspection Cycle of Tackles
The visual inspection and static load test for the tackle shall be carried out on a quarterly basis.The dismantling inspection shall be carried out semi-annually based on the visual inspection and the static load test.The new tackle shall be inspected according to the above requirements after half a year of use.