Planetary and worm gears differ fundamentally in the way they function.
With worm gears, the contact surfaces of the gear teeth glide on each other like a ski on snow. This makes the worm gear a very quiet option during operation. At the same time, the surfaces are subject to wear due to friction and part of the energy is converted into heat, resulting in a lower level of efficiency. Therefore, a material with good emergency running properties such as bronze is used. The axesof the gear wheels are always arranged at a right angle to each other and offset. Therefore the motor is always positioned at 90° to the output axis and is offset in height by the center distance. Worm gears can be manufactured with only one (1) tooth. Therefore high reduction ratios can be realized in one gear stage. This makes the worm gear unit simpleand compactindesign. Worm gears are also available with a hollow shaft or double-sided shaft.
The contact surfaces of planetary gears on the other hand roll against each other like a car wheel on the road. Wear is therefore minimal and their efficiency is high. However, more noise is generated during tooth engagement, making the planetary gear loudercompared to the worm gear. Steel can be used as a suitable material, which allows for high loadcapacities. The axisof the motor and the gear are coaxial, which means the planetary gear acts as an extension of the motor axis. Planetary gears can have high reduction ratios. To realize this, several gear wheels (gear stages) have to be installed. This leads to the fact that the gear unit becomes more complex in its structure as the reduction ratio increases. This also increases the costs the higher the reduction ratio becomes.