A simple lifting mechanism that vertically lifts heavy objects through a sprocket or drum. It is lightweight, compact in structure, and easy to use, suitable for simple lifting work in construction. Lifting blocks can be divided into single-sheave blocks, double-sheave blocks, and multi-sheave blocks according to the number of sheaves. According to the connection method between the block and the lifted object, they can be divided into four types: hook-type blocks, chain-ring-type blocks, ring-type blocks, and suspension-frame-type blocks.
A lifting block is an important lifting tool. It has a simple structure and is easy to use. It can repeatedly change the direction of the traction steel rope of the block and block group, and lift or move rotating objects. Especially, the block group composed of blocks combined with a winch, mast, or other lifting machinery is widely used in construction and installation operations. Product specifications range from 0.03 to 320 tons, with wheel systems from single-wheel to ten-wheel. Lifting attachments include hooks, chain rings, rings, and lifting beams for users to choose from. It is convenient to use, has a wide range of applications, and can be operated manually or mechanically. It is mainly used in factories, mines, agriculture, electric power, construction, and other production and construction sites, as well as for machine installation and cargo lifting in docks, shipyards, and warehouses.
A single lifting block can only change the direction of force and cannot save effort; however, a block group composed of two blocks can achieve the purpose of saving effort while changing the direction of force. During lifting and transportation operations, a single-sheave block can be used as a guide block; a block group can be used with a winch for lifting purposes.
The ball and roller bearing wheel cores used in lifting blocks are national standard bearings, with two per sheave. Different specifications can be adopted according to the lifting tonnage. Standard bearings are suitable for high-speed rotation and are maintenance-free.
Lifting blocks, also known as iron blocks or pulleys, are used in lifting operations in conjunction with rigging, lifting attachments, winches, etc., to transport and hoist various structural equipment and components. They are indispensable lifting tools.
Pulleys are divided into fixed pulleys, movable pulleys, guide pulleys, and pulley blocks according to their usage nature.
(1) Fixed pulley. A fixed pulley is used to support the movement of flexible parts. When the rope is under force, the rotor rotates, but the position of the shaft remains unchanged. In use, it can only change the direction of the steel wire rope and does not save effort.
(2) Movable pulley. A movable pulley is installed on a moving shaft and rises or falls together with the object being towed. Using a movable pulley saves effort, but it cannot change the direction of force application.
(3) Guide pulley. A guide pulley, also known as an open-side pulley, is similar to a fixed pulley and can only change the direction of the rope without saving effort.
(4) Pulley block. A pulley block is a lifting tool composed of a certain number of fixed pulleys, movable pulleys, and rigging. It can reduce traction force and change the direction of pull. In hoisting engineering, pulley blocks are often used to lift heavy mechanical equipment with less traction force. For example, when using a 0.5 to 20 ton (5 to 200 kN) winch to pull the outgoing rope end of a pulley block (commonly called the running line), it can complete the hoisting task of equipment or components weighing from several tons to hundreds of tons.
