Worm gear on our pan-tilts

Quickset is known for its large pitch steel worm gear design, not only is it very robust, but it is also self locking. When the pan- tilt is in use you can overhang the load, cut the power, and the load will stay stationary. The locking attribute is superior for mobile applications. Another advantage is its modularity. The unit can be easily retrofitted to any application. Quickset’s main focus on design is for durability and long life.
The principle of worm gears dates back as far as the Archimedes screw and was also the subject of sketches produced in the 15th century by Leonardo da Vinci.
Worm gear drives have the advantage of high resistance to being reverse driven from external forces (back drive). This inherent function can be used in situations where it is not desirable to maintain drive power to the drive motors to keep the mechanical system in place. Mobile, high winds and / or heavy load situations can create back drive torques that would be intolerable for most applications. To help visualize this concept the figure below shows a characteristic current / voltage (I -V) curve produced by a rectifying diode. An analogous effect is produced by a worm drive system in its characteristic torque / motion (T- D) curve.

In addition, compact gear reduction reduces the pan-tilt size considerably. It would take about three gangs of 3:1 reduction gears to do the same work as a single worm meshed with a 24 tooth round gear.
One negative attribute is that the worm gear uses predominantly sliding friction when advancing the teeth of the round gear. The teeth of round gears are generally designed to minimize sliding effects when they are meshed with each other.
As a power transmission medium, worm gears are generally viewed as "mature" technology.
However, this analysis is quickly disproved if one considers the range of precision tasks that contemporary worm gear systems are required to perform.
Modern dual lead worm gears are used in telescopes, dicing machines that cut silicon chip wafers. They are also increasingly the first choice for use in machine tool positioning tables, cutter drives on milling machines, and robotic arms.

What has made the evolution of worm gears possible to perform these precision tasks is the continuous improvement in production methods leading both to higher accuracy and also greater efficiency in gear performance.

By the Engineering Department at QuickSet