I. Structural Analysis

Construction hoists are indispensable vertical transportation machines in construction projects. Through over forty years of continuous development, China's construction hoists have achieved remarkable success, featuring advanced technical performance, stable product quality, and significant price advantages. They have become essential equipment in the construction process. However, due to the structural characteristics of traditional construction hoists, tip-over accidents causing equipment damage and casualties still occur during construction, posing safety hazards. With the rapid development of construction projects, higher requirements have been placed on the safety performance of construction hoists. Based on the pursuit of higher safety and the goal of preventing tip-over accidents, a new type of U-shaped construction hoist has been developed through innovative improvements and optimized design based on existing models. The most significant feature of the U-shaped construction hoist is that the cage is balanced front-to-back and left-to-right relative to the suspension point of the drive frame. Simply put: the left and right cages of a traditional construction hoist are connected as one unit, forming a U-shape. During the overall structural design process, the suspension point of the drive frame is positioned at the center of the cage structure, ensuring that the cage is relatively balanced front-to-back and left-to-right relative to the suspension point. This design has been granted national patents: A New Type of U-Shaped Construction Hoist for Building Use (201420502103.3) and An H-Shaped Construction Hoist for Building Construction (201621441537.2).

As is well known, the structural characteristic of a traditional construction hoist is that it has one cage on each side of the mast, each with its own independent drive mechanism, allowing them to operate independently. Precisely because of this, a single cage operating independently generates a bending moment on the mast. It is due to this unbalanced moment that when equipment maintenance is improper or operational errors occur, tip-over accidents leading to equipment damage and casualties can happen.

Force Analysis of the Two Models: (Analysis pending)

Figure ①: A traditional construction hoist cage has a self-weight of 1.2 tons. When running empty and independently, the bending moment generated on the mast is 0.96 t·m.

Figure ②: A traditional construction hoist cage has a self-weight of 1.2 tons. When running independently with a 2-ton load, the bending moment generated on the mast is 2.56 t·m.

Figure ③: A U-shaped construction hoist has a self-weight of 1.6 tons. When running empty and independently, the bending moment generated on the mast is 0 t·m.

Figure ④: A U-shaped construction hoist has a self-weight of 1.6 tons. When running with a 1-ton load in each of the left and right cages, the bending moment generated on the mast is 0 t·m.

Figure ⑤: When a U-shaped construction hoist with a self-weight of 1.6 tons runs with only the left cage loaded with 2 tons of cargo, the bending moment generated on the mast is only 0.96 t·m.

Through the force analysis of the five scenarios above, under the most severe unbalanced loading condition, the overturning moment exerted on the mast by the U-shaped construction hoist is only equal to the overturning moment generated by an empty traditional construction hoist cage. In contrast, the overturning moment exerted on the mast by a traditionally loaded traditional construction hoist under normal full-load conditions is three times that of the U-shaped construction hoist under its most severe unbalanced loading condition.

In its structural design, the U-shaped construction hoist consistently adheres to the principle of aligning the suspension point with the section centroid and the center of gravity, ensuring the cage is relatively balanced front-to-back and left-to-right. (As illustrated in the diagram.)

      

 

In summary: It is precisely due to the structural characteristics of the U-shaped construction hoist that the equipment maintains relative front-to-back and left-to-right balance whether during normal construction or during installation and disassembly processes, effectively preventing the occurrence of tip-over accidents.

As an innovation and supplement to traditional double-cage construction hoists, the U-shaped construction hoist effectively addresses issues found in traditional models, such as eccentric structural defects, high vibration and wear in the transmission system, and high overall energy consumption and costs. It demonstrates significant advantages when applied in low-to-mid-rise buildings, prefabricated construction, and bridge construction projects. As a replacement and upgrade product for simple hoists, it offers higher reliability and safety.

 

     

 

 

 

 

The U-shaped construction hoist cage utilizes a sheet-assembly patented technology titled "A Combined Cage for a Hoist" (Patent No. 201721082414.9*). Therefore, during installation and disassembly, the equipment is not constrained by site dimensions, road conditions, lifting equipment availability, or other factors, and can be assembled and disassembled manually. It serves as a substitute for simple tower headframes. (The sheet assembly is illustrated in the diagram.)

 

 

II. Load Capacity Analysis

Due to their low unit weight (600 kg/m³) and excellent sound insulation, thermal insulation, and moisture resistance, lightweight foamed cement bricks effectively reduce the overall structural cost of buildings. As a result, they are widely used as partition wall materials in high-rise buildings. (As shown in the figure.)

 

Through statistical analysis of extensive construction site data, during the interior finishing process of high-rise buildings, the primary function of construction hoists is to transport materials needed for partition walls. Among these partition materials, lightweight foamed cement bricks account for 95% of the total transportation volume (the ratio of floor area to interior wall area is 1:2.6; based on 600 square meters per floor, using 15cm thick lightweight foamed cement bricks, the total volume of bricks required is 600 × 15 × 2.6 = 234 cubic meters). Due to the large volume but light weight of lightweight foamed cement, each cage of a traditional construction hoist can only carry either two wheelbarrows or one battery-powered cart. The maximum transport capacity per cage is 1 cubic meter, weighing approximately 500 kilograms. Adding the weight of the transport vehicles, the total load does not exceed one ton. This weight is far below the rated load capacity of conventional traditional motors, resulting in wasted motor power. With rising labor costs, many units with refined management have adopted electric tricycles for material transportation instead of manual wheelbarrows. Under these transportation conditions, one cage can still only carry a single electric tricycle. However, using a U-shaped construction hoist, it can transport four wheelbarrows at once—two on each side—or two electric tricycles. The transport capacity per trip of a U-shaped construction hoist is twice that of half a cage of a double-cage construction hoist (as illustrated), meaning the transport capacity per unit time is identical for both types of elevators.

 

Example: Let us calculate based on both types of hoists operating at a speed of 34 meters per minute. Suppose we need to transport 24 loads of materials to a height of 68 meters (22 floors). Loading takes 3 minutes, ascending to 68 meters (22 floors) takes 2 minutes, unloading takes 3 minutes, and descending takes 2 minutes. One complete round trip totals 10 minutes, meaning 6 round trips per hour. For 24 loads of materials: A double-cage construction hoist requires 12 round trips (6 trips per cage, with 2 loads per trip). A U-shaped construction hoist requires 6 round trips (with 4 loads per trip). Therefore, the transport capacity of the two different construction hoists within the same time frame is identical. The only difference is that the traditional double-cage construction hoist provides 12 opportunities for personnel to board at ground level within one hour, while the U-shaped construction hoist provides 6 opportunities. However, the operating cost differs by a factor of two (as shown in the table). In summary: Regardless of the building's height, as long as the hoist's operating speed remains constant, the transport capacity within the same time frame is identical whether using a double-cage construction hoist or a U-shaped construction hoist.

 

III. Cost Analysis

Comparative Analysis Table

In summary: Under the current premise of using lightweight foamed bricks, whether employing a double-cage construction hoist or a U-shaped construction hoist, as long as both machines operate at the same speed, the volume of material transported is equal. However, using a U-shaped construction hoist can save 16,920 yuan per month (including monthly labor costs, rental fees of 9,000 yuan, and electricity costs of 7,920 yuan). (Calculated based on: electricity rate of 1.1 yuan/kWh, 8 hours/day, 30 days/month, 10 months/year — theoretical results.)

Example: A construction company within a group has an annual output value of 100 billion yuan. Considering residential buildings with 33 floors, each floor covering 600 square meters, the construction cost per building is approximately 50 million yuan. An output value of 100 billion yuan corresponds to roughly 2,000 such buildings. If one construction hoist is used per building, and each hoist saves 169,200 yuan annually, then for 1,000 buildings, the group could save 169.2 million yuan per year.

The floor is the workers' construction site. During the construction process, every trade and every procedure — whether concrete pouring, formwork installation, rebar tying, wall masonry, or plastering — operates under strict quota management. The main task of the hoist is to deliver materials to the designated work surface. As long as we strengthen management during construction and the travel of workers and supervisors, it can bring economic benefits to the enterprise.

As economic development enters an era of high-quality growth, safe and efficient development has become the primary goal for enterprise managers. On the premise of meeting construction requirements, rationally selecting equipment is a prerequisite for safe production and a measure for managers to enhance operational efficiency.

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Guangxi Hongtao Construction Machinery Equipment Leasing Co., Ltd.

January 5, 2021