What are the self-locking conditions of worm gear reducers?

Abstract: The structure and transmission of worm gear reducers are realized through friction, so they have a self-locking function. When self-locking, the worm can easily rotate the worm wheel, but the worm wheel cannot rotate the worm. However, to achieve self-locking, certain conditions must be met. When the unfolded helix angle of the worm is less than the friction angle of the worm gear contact, it can be self-locking. In addition, it should be noted that not all worm gear reducers can be self-locking. Generally, the reduction ratio is required to be greater than 40 to have a good self-locking function. Let's take a look at what the self-locking conditions of worm gear reducers are.

1. What does self-locking of worm gear reducers mean?

Worm gear reducers are a special reducer. Compared with ordinary gear reducers, they have a special function, that is, self-locking function.

The so-called self-locking is automatic locking, that is, the worm can easily rotate the worm wheel, but the worm wheel cannot rotate the worm. Since the structure and transmission of the worm gear are realized through friction, when certain conditions are met, the worm gear reducer can be self-locking.
The self-locking function of the worm gear transmission method is very useful in mechanical applications, such as winches, conveying equipment, etc. However, due to the friction transmission method of the worm gear, the transmission efficiency of the worm gear is much lower than that of the gear transmission.

2. What are the self-locking conditions of the worm gear reducer?
For the worm gear reducer to self-lock, certain conditions must be met. Generally speaking, the condition requires that the unfolded helix angle of the worm is less than the friction angle of the worm gear contact, that is, &beta;<&Phi;, &beta; is the unfolded helix angle of the worm, &Phi; is the friction angle; tg&Phi;=&mu;, &mu; is the friction coefficient.
This principle is the same as the object on the inclined plane not sliding down, that is, G*sin&alpha;<G*cos&alpha;*&mu;, &alpha; is the inclined angle of the inclined plane, &mu; is the friction coefficient, and G is gravity. It is sorted out: tg&alpha;<&mu;, that is: &alpha;<arctan&mu;=&Phi;. When the helix angle of the worm is very small and less than the friction angle, the self-locking function can be achieved.

3. What is the minimum speed ratio for the self-locking of the worm gear reducer?
When a reducer with a self-locking function is needed, a worm gear reducer is usually selected. However, not all worm gear reducers have a good self-locking function, and generally a certain reduction ratio is required.

Generally speaking, the reduction ratio of the worm gear reducer should be greater than 40 to achieve the self-locking function. If a stronger self-locking function is required, a larger reduction ratio should be selected as much as possible, or a brake motor should be matched for use.