Like all gear reducers, worm gears are used to increase torque while slowing output speed. However, worm gears are unique in that they include a worm—a cylindrical screw that reduces the gear ratio—that is set at a ninety-degree angle to the worm wheel. Overall, worm gears require less space than spur gears. Let’s review the uses and benefits of worm gears.
Applications for Worm Gear Reducers
Single-start worm gears operate in one direction only; due to high friction between the worm and the worm wheel, the worm cannot be driven backwards. This makes worm gears ideal for hoisting operations in which a reversal of transmission direction would be dangerous and/or damaging. Heavy gates are often controlled with worm drives for this reason.
Due to their compact nature, worm gear reducers are often used in small electric motors. You will also find worm gear reducers in rudders, conveyor systems, presses, mining applications, and metalworking. Stringed musical instruments are typically tuned with small worm gears. Elevators and escalators also commonly feature worm gear reducers, due to their non-reversibility.
Advantages of Falk Worm Gear Reducers
Exceptional Cost-to-Torque Ratio. Engineers typically select reducers by comparing their cost to the torque they provide. Worm gear reducers are perennial champions as far as returning torque for the buck. Why? Because they provide more input shaft rotations per output shaft rotations. In a single stage, a worm gear reducer can commonly deliver 60:1 gear reduction. A helical reducer, in contrast, would require three stages of gearing to produce such speed reduction. With fewer gears and bearings involved in a single stage, worm reducers cost less to implement.
Widely Available and Easily Interchangeable. Gear manufacturers (including Falk) tend to maintain a broad inventory of worm gear reducers. Moreover, worm gears’ mounting dimensions are universal across manufacturers; gear ratios have also been standardized. With worm gear reducers, engineers don’t have to fret over the shaft height, length, or diameter. Dimensional consistency facilitates worm reducer replacement.
Provides Backup Breaking. Single start (single spiral) worm gears function in one direction only. As such, worm gears act as backup breaks; the load can only be transmitted from the reducer to the load, an ideal setup for lifting applications. Indeed, OSHA recognizes worm gears as control breaks for hoist systems. As backup breaks, Falk worm gear reducers prevent the load break from releasing suddenly, which can cause overheating and premature failure.
Fewer Moving Parts than other Load Break Options. The simplicity of worm gear designs is an advantage. The more complex a system, the more opportunities for failure.
Flexible Mounting Choices. In a worm gear reducer, the gear is mounted on the output shaft at a 90- degree angle to the input shaft. This frees up both ends of the output shaft for more engineering design options. Moreover, both solid and hollow output shafts may be used with worm gear reducers. Hollow output shafts are gaining popularity, as they remove the need for belts or chains which transmit torque from solid shaft reducers. Again, fewer moving parts translates to less need for repair.
Lower Noise Levels. Sudden gear tooth contact is common in bevel and helical gearing; this creates ambient noise, which plant managers must minimize to meet OSHA industrial hygiene standards. Worm gears run more quietly because the gear teeth slide into contact with each other, and because there are always more gear teeth touching the gear mesh. Moreover, because a worm gear will require a single stage where other reducers would require two or more gear stages, less noise is created overall.
In addition to all these advantages, worm gear reducers have a lifespan that’s comparable to other reducers. Worm gears have brought innovation to various industries throughout history, from ship- building to automobile manufacturing. They continue to enjoy popularity among engineers, due to the many advantages they offer.
Posted under Machinery Maintenance, Products/Services on Monday, January 19th, 2015