Views:3 Author:Site Editor Publish Time: 2018-02-09 Origin:Site
The pulley block is a simple machine assembled by several movable pulley and fixed pulley, which can save energy or change the direction of force. The labor force of the pulley block is determined by the number of the rope, and its mechanical efficiency is determined by the gravity of the object being pulled, the gravity of the movable pulley and the friction.
The role of pulley and pulley block.
The pulley supports and guides the rope movement, and plays a guiding and balanced role. The pulley block is composed of a certain amount of movable pulley and fixed pulley. It has the characteristics of moving and fixing the pulley, and the pulley is divided into two kinds: the pulley and the movable pulley. The fixed pulley only changes the direction of the force.
The movable pulley can save energy. Therefore, the pulley block can change the direction of the force and save energy. It can also be used as a deceleration or growth device. When the weight is large, it is advisable to use the large ratio of the pulley block to reduce the tension of the wire rope; When the weight is lighter, it is advisable to use the smaller number of the pulley block to reduce the number of the wire rope and improve the working efficiency.
The pulley block composed of steel wire rope, fixed pulley and movable pulley is an important part of crane hoisting mechanism. According to the effect of pulley, it is divided into two kinds: the labor-saving pulley block and the growth speed skating group. The pulley block is divided into two types: single - link and double - slip.
Scrapping standard of pulley
In one of the following situations, the pulley shall be scrapped:
Crack (not to be resoldered);
The uneven wear of the wheel groove reaches 3mm;
The thickness of the wheel groove wall is 20% of the original size;
Due to wear and tear, the bottom diameter of the wheel groove is reduced by 50% of the diameter of the wire rope;
Other items that conform to the conditions of abandonment.
Maintenance of the pulley block.
(1) single beam bridge crane to dismantle and overhaul the pulley block, check the cracks;
(2) overhaul of pulley groove;
(3) inspection of axle hole;
(4) the assembly;
(5) no cracks shall be found on the sliding wheel shaft. The shaft neck shall not wear 30% of the original diameter, and the taper shall not be more than 5%.
(6) check the pulley groove with the sample, and the radial wear should not exceed 30% of the wall thickness, otherwise it should be scrapped. Shall not exceed the standard can be mended, with sample check after overhaul, the bottom and side clearance should not be greater than 0.5 mm, the center line of the wheel groove and the roller center line deviation should not be greater than 0.2 mm, end of the rope groove center for contour deviation should not be greater than 1 mm;
(7) after the overhaul of single-beam bridge crane, the axle hole shall be allowed to have defects not exceeding 0.25CM2, and the depth should not exceed 4mm;
(8) after assembly, the hand should be able to rotate flexibly, and the lateral swing shall not exceed D/1000. D- the nominal diameter of the pulley.