What is a reduction gear?

Below, we will introduce the mechanism, applications, and necessity of gear reducers. A thorough understanding of gear reducers and their proper use is essential for selecting the model that best meets your requirements.

The Mechanics of Reduction Gears

A reduction gear is a gear mechanism that lowers the rotational speed of a power source, such as a motor. It also increases torque, allowing you to set the appropriate speed and torque for your specific application.

A simple reduction gear consists of two gears: one on the input side and the other on the output side. The ratio of the number of teeth on each gear is known as the reduction ratio.

For example, if the output gear has 100 teeth and the input gear has 50 teeth, the reduction ratio is 2:1. In this case, the output gear’s rotational speed will be half that of the input gear, while the torque at the output gear will be nearly twice that of the input gear. (More precisely, the output torque equals the input torque multiplied by the reduction ratio and the gear’s torque transmission efficiency.)

In many situations where speed reduction is required, a simple two‑gear arrangement may not suffice. For instance, achieving a high gear ratio with just two gears necessitates an input gear that is very small (with few teeth) and an output gear that is very large (with many teeth). The gear ratio attainable with only two gears is subject to physical limitations.

One solution is to add more gears to the assembly, so that the output gear becomes the input gear of the next stage in the reducer. These are referred to as gear stages. A single set of gears constitutes one stage; two sets of gears constitute two stages, and so on.

By using more gears, a higher gear ratio can be achieved. However, as the number of gears increases, torque transmission decreases, and backlash on the output shaft also grows.

For applications requiring high precision, the reducer should be manufactured with precisely machined gears and components. A design that minimizes backlash should be selected.

In addition, most gear reducers use lubricants such as grease to ensure smooth operation, reduce noise, and significantly extend service life. The appropriate lubricant should be selected based on the reducer’s operating environment and mechanical conditions, such as load and speed.