To the uninitiated, the suggestion that gears may not always be round may strike people as odd, if not absurd. However, as Brian Dengel illustrates in his article in Gear Solutions magazine, this is sometimes the case.
Noncircular or irregular gears differ from traditional gears in both shape and functionality. The article outlines how and why irregular gears are suited to specific applications.
‘Noncircular gears feature varying radii that result in non-uniform motion between the driving and driven shafts’. This leads to an uneven transmission of motion suitable for applications requiring differing areas of speed. Most common types of irregular gears include oval, elliptical and cam profiles.
Unlike traditional gears, contact does not occur at a constant point along the circumference. Therefore, significant design calculations are necessary to ensure the smooth engagement of the teeth.
So what applications are noncircular gears used for?
Applications where the transmission motion needs to be non-uniform. In the early days, mechanical clocks used noncircular gears to achieve different rates of movement for the hands. Printing was another early application to control the feed speed of the paper where the process needs to adapt to paper thickness or media.
Other applications that use noncircular gears are:-
Conveyor systems – where differing speeds are needed during processes like sorting or packaging
Robotic systems – requiring precise and variable motion control
Aerospace and defence applications that require high precision and variable motion such as aircraft actuators or weapon systems.
Agricultural machinery – seeders, ploughs and harvestors requiring variable speed control.
So, noncircular or irregular gears crop up more regularly than many would assume, read more here.