Double Pulley Block: An Efficient And Labor-Saving Tool Forged by The Factory

In the field of lifting and handling as well as mechanical transmission, the double pulley block, with its unique structure and powerful labor-saving function, has become a key equipment to improve work efficiency. This mechanical device, composed of two pulleys combined through a frame, can multiply the acting force by means of the rope winding method, playing an irreplaceable role in industrial production, construction and other scenarios. As a factory specializing in the production of double pulley blocks, we always focus on precision manufacturing, safety and reliability, creating lifting auxiliary equipment with both strength and efficiency for various industries.

The scientific proportion of materials is the basis for the bearing capacity of the double pulley block. The pulley body is made of high-strength cast iron HT300, whose tensile strength reaches 300MPa, and internal stress is eliminated through aging treatment to ensure no deformation under long-term load; The shaft core is made of 45# steel after quenching and tempering, with hardness controlled at HRC28-32, which not only ensures sufficient strength but also has good toughness to avoid fracture under force; For outdoor double pulley blocks that need rust prevention, the frame is welded with Q235B carbon steel and then hot-dip galvanized as a whole, with a zinc layer thickness of more than 85μm, which can pass 500-hour salt spray test without rust, adapting to open-air working environment. All raw materials must pass metallographic analysis and mechanical property testing to eliminate inherent defects such as pores and cracks.

The precision of the production process determines the operating efficiency of the equipment. The pulley groove is processed by CNC lathe forming, with groove tolerance controlled within ±0.1mm and surface roughness Ra≤1.6μm, reducing friction loss when the rope contacts the pulley; The fit between the shaft sleeve and the shaft core adopts clearance fit H7/g6, ensuring that the rotation clearance is between 0.03-0.08mm, and low resistance rotation is achieved with lithium-based grease, keeping the mechanical efficiency above 95%; The frame welding adopts carbon dioxide gas shielded welding, the weld leg height is designed according to 1.5 times the bearing capacity, and after welding, aging treatment is carried out for 24 hours to eliminate welding stress, then X-ray flaw detection is used to check the internal quality of the weld. In the assembly process, a torque wrench is used to tighten all connectors according to the specified torque to ensure no loose noise during operation.

The whole-process quality inspection builds a safety defense line. In the static load test, the double pulley block must bear 3 times the rated load for 10 minutes, and all components have no plastic deformation; The dynamic fatigue test simulates the actual working condition, and after 100,000 cycles of lifting under 1.2 times the rated load, the wear of the pulley groove must not exceed 0.2mm; The rotation flexibility is measured by a tachometer, and the speed fluctuation range is controlled within 5% under the rated load. Each double pulley block leaving the factory is accompanied by a detailed inspection report, marking the load level, test data and production date, and establishing a traceable quality file.

The double pulley blocks produced by us have been widely used in many scenarios: on construction sites, 5-ton double pulley blocks are used with cranes to easily hoist precast slab components; In logistics warehouses, manual hoists are matched with double pulley blocks, enabling workers to pull 500N goods with 100N force; When installing stage equipment, small double pulley blocks accurately control the lifting and positioning of the lighting frame; Even in the agricultural field, double pulley blocks are used for lifting and debugging irrigation equipment. In these scenarios, the double pulley block, with its labor-saving and efficient characteristics, significantly reduces labor intensity and improves operation safety.

As a producer of double pulley blocks, we are well aware that each piece of equipment is related to the life safety of operators and work efficiency. In the 16 processes from raw material cutting to finished product packaging, we integrate the safety concept into every detail with millimeter-level precision control and ultimate load testing. In the future, we will develop lightweight alloy materials and self-lubricating bearing technology to reduce the weight of the equipment while maintaining the bearing capacity, so that the double pulley block can play the value of high efficiency and labor saving in more fields and become a reliable assistant in industrial production and engineering construction.