Worm Gear Motors
What Is a Worm Gear Motor?
A worm gear motor drives two interconnected shafts, resulting in their combined rotation. The first shaft, the one that is connected to and driven by the power source, is called the “worm.” With a spiral thread along its length, similar to that of a screw with a V-type thread, the spiral grooves fit around the teeth of a wheel-shaped shaft (similar to a spur gear) that intersects the worm at 90 degrees. As the motor turns the first shaft, the second gear (sometimes called a “worm wheel”) is then turned as well.
A single start worm will have a single thread along its length. This means that per one revolution of the shaft, the wheel advances by just one tooth. As implied by the obvious name “single start”, it is possible to have more than just one spiral on the worm. Predictably, two starts would equal the advancement of two teeth per revolution of the worm shaft and three starts would give you three teeth per revolution.
The gear reduction is calculated by the ratio of teeth to threads. So a single start worm and a worm wheel gear with 24 teeth would equal a gear reduction of 24:1. Meanwhile, a two start worm and a worm wheel with 24 teeth would have a gear reduction of 24:2.
What Advantages Does A Worm Gear Offer?
A motor with a worm gear is not a high-speed motor and is intended to operate at relatively low speeds. However, in consideration of their size and speed, their relative amplification of power is quite impressive. Making them powerful motors for a variety of low-speed applications.
Additionally, due to the teeth and worm design, the worm can turn the teeth, but the teeth cannot turn the worm. Because the power relationship is one-sided, worm gear motors are good for braking without the need for an external brake in order to stop, making stopping a much simpler process (however, a secondary, external brake should still be included in the assembly as an added safety precaution). If the gear ratio is high enough, the worm design will avoid “back-drive” by the system. The unidirectional relationship of the power combined with the excellent amplification of power makes these types of motors ideal for holding a load in place when power is off. These two factors make them a great option for motors used in lifts, elevators, and hoists.
Another advantage of a worm gear motor is that they are much quieter than other types of gears. The sliding movement as the worm shaft rotates is, not surprisingly, quieter and smoother than two sets of teeth clicking into place. This elimination of noise is helpful for motors that are used in places that are ideally as quiet as possible, such as movie theaters and elevators.
Another design feature used in worm gear motors is their unique combination of metals. One gear is intentionally made of a softer metal than the other, allowing it to better absorb energy from a sudden shock. Because of this design element, even if a sudden halt is made, the secondary brake is less likely to need to be engaged as the gear should hold under the impact. This makes worm gear motors great for rock crushers and other heavy-duty machinery that could deal with tough impact.
Finally, worm gears help to save space. They have a high gear ratio because they require fewer gear sets than other types. Having fewer parts means that less space is required inside the gearbox and it can be smaller. This advantage is helpful in manufacturing and packaging industries where often multiple apparatuses are needed to complete a process, making every square inch valuable. Again, this advantage is combined with their ability to stop and hold a load (often a requirement of both the packing and manufacturing industries), so worm gear motors are commonly used to power packaging equipment and conveyors.
When considering their power output ratio, efficient braking and holding, noise reduction, durability, and small size, it is obvious why there are so many applications for worm gear motors.
How Can We Help You?
If you are considering that a worm gear motor may be the kind of power source you need for your project or if you already know that you need a worm gear motor but require assistance to select the right one, please do not hesitate to reach out to our team of highly qualified professionals here at Telco. We are happy to review your needs or concerns and help you to come to the best decision to make your project a success.