The worm screw lift jack, also known as the worm drive mechanism, is primarily used to convert rotary motion into linear motion or vice versa. The lift jack consists of a worm gear reducer and a screw, with the worm gear being the减速 element, driving the worm to achieve reduction. The worm gear acts as the nut for the lift screw and is matched to it.

Frequently Asked Questions and Their Causes

1. Elevator overheating and oil leakage

To improve efficiency, worm gear lifters use non-ferrous metals for the worm gears and slightly harder steel for the worms. Due to sliding friction transmission, a considerable amount of heat is generated during operation, causing differential thermal expansion between the lift's components and seals. This results in gaps forming at the mating surfaces. The lubricating oil becomes thinner with the increase in temperature, which easily leads to leakage.

The primary reasons for this situation include four factors: 1) an irrational material match; 2) poor quality of the mating and friction surfaces; 3) incorrect selection of lubricant quantity; and 4) subpar assembly quality and operating environment.

Gearbox Wear

Worm gears are typically made of tin bronze, with the matching worm material hardened to HRC 45-55 using 45 steel, or hardened to HRC 50-55 with 40Cr and then ground on a worm grinding machine to a roughness of Ra0.8μm. The lifting machine operates with slow wear during normal operation, and some lifting machines can be used for over 10 years. If wear occurs at a faster rate, it is necessary to consider whether the selection is correct, if it is operating under overload, and factors such as the material, assembly quality, or operating environment of the worm and worm gear.

3 Small Bevel Gear Wear

In vertical installation elevators, the main issue is often related to the amount of lubricating oil added and the type of oil. During vertical installation, it's common for insufficient lubricant to be added, leading to the loss of transmission gear oil between the motor and the elevator during operation cessation. This results in inadequate lubrication protection for the gears. When the elevator starts, the lack of effective lubrication can cause mechanical wear or even damage due to the gears not receiving proper lubrication.

4 Helical Gear Bearings Failure

During malfunctions, it is often found that the gear oil inside the elevator is emulsified, and the bearings are rusty, corroded, and damaged, even when the gear box is properly sealed. This is due to condensation water produced when the gear oil temperature rises and then cools during the elevator's operation, mixing with the water. Of course, it is also closely related to the quality of the bearings and the assembly process.

Solution

1. Ensure Assembly Quality

When purchasing or manufacturing tools for disassembling and installing elevator components, avoid using hammers or other tools for striking; when replacing gears, worm gears, and worm shafts, opt for original factory parts and replace them in pairs; when assembling the output shaft, pay attention to the tolerance fit; use anti-adhesive agents or red lead oil to protect the hollow shaft to prevent wear and rust, or the accumulation of debris on the mating surface, making it difficult to disassemble during maintenance.

2 Selection of Lubricants and Additives

The蜗齿升降机 typically uses 220# gear oil. For hoists subject to heavy loads, frequent startups, and poor operating environments, it is advisable to use some lubricant additives. These additives ensure that the gear oil remains adhered to the gear surfaces when the hoist is at rest, forming a protective film that prevents direct metal-to-metal contact under heavy loads, low speeds, high torques, and during startups. The additives contain sealant regulators and anti-leak agents, which maintain the flexibility and elasticity of the seals, effectively reducing oil leakage.

Selection of Elevator Installation Positions

Where possible, avoid vertical installation. When vertical installation is used, a significantly larger amount of lubricating oil is required, which can easily lead to overheating and oil leakage in the elevator.

Establish a Lubrication Maintenance System

Maintain elevators according to the "Five Fixed" principle for lubrication work, ensuring each elevator is regularly inspected by a designated person. In case of significant temperature rise over 40°C or oil temperature exceeding 80°C, degradation in oil quality, presence of excessive copper powder in the oil, or abnormal noise, stop using the elevator immediately, conduct timely repairs, eliminate the fault, and replace the lubricating oil. When refueling, pay attention to the oil level to ensure proper lubrication for the screw elevator.