Gears: Different Types and Applications for Robotics
Gears are used to connect two shafts usually to transmit rotational motion with rigid components. Despite the advancement of technology, certain types of gears still exist, thanks to their reliability and standardized ways to make them. In this article, different types and applications of gears will be discussed to emphasize how beneficial gears are in the robot making industry.
Your robotics project might need more than just connecting the shaft to electric motors, and using gears might be a solution. However, there are different types of gears, and they all have different applications in different situations. Gears can be classified into a parallel axis, nonparallel axis, and special application gears due to their form, position, and teeth shape.
Parallel Axis Gears
Parallel axis gears, as its name implies, connect parallel shafts to transmit rotational motion. Formed as toothed cylinders meshing with each other, a gap exists between the teeth called backlash. The simple construction, however, makes an efficient power transfer.
The simplest gear of all, it is what most people think when they think of gears. It has a small speed ratio range and is widely used as a motion transmission solution. When using it in robots, consider the speed, backlash, and speed ratio, since it becomes noisy at high speeds.
It is a modified spur gear, which has slanted teeth to solve the noise issue at high speeds. Because helical gears have slanted teeth, it can be reassembled to connect nonparallel shafts. For robot makers, consider its lubrication and maintenance, since it wears faster than spur gears.
Also called double helical gears, the teeth of herringbone gears are also slanted. However, teeth are slanted in two directions forming a V-shape, which cancels the screw action of having only a single slant. The modifications make the herringbone gears more expensive but are beneficial for robot makers.
Nonparallel Axis Gears
Nonparallel axis gears have various forms and shapes. They have higher speed ratios than parallel axis gears and are more expensive because of their unique structures. However, their misaligned axes make them perform best for cases where they are applicable.
It is the reassembly of helical gears, which was mentioned earlier. Unlike its original form, it is noisy and inefficient. Because of that, it is rarely used, which also applies when making robots.
It is a modification of spur gears, where the base shape is a cone instead of a cylinder. Usually, bevel gears connect two shafts of 90 degrees. For robot makers, it is an option for robots that need to reach complex areas.
It is a modified bevel gear, where the teeth are spiral, and the shaft center lines do not intersect. Hypoid gears are silent like helical gears, but it has a long service life. It needs extreme pressure oils as seen in boats and industrial machines.
When in need of a locking ability and higher speed ratio, worm gears are a substitute for hypoid gears. Basically, a screw that drives a helical gear, the motion transmission is only one way. It has a low efficiency because of the rubbing of the screw and the gear, which makes it rarely used in making robots.
Special Application Gears
Another alteration of spur gear, ring gears or internal gears also connects parallel shafts. One of the gears is formed as a ring, which is larger than the other, and the teeth are ground inside. Usually, the small gear is connected to the motor to drive the part connected to the ring.
Planetary gears are made to solve the issue of spur gears and ring gears having few contact points, which limits the torque transferred. Also called epicyclic gears, it consists of a sun gear, a ring gear, and two or more planetary gears. The high torque capacity makes it optimum for power dense machines such as automobiles.
Rack and Pinion
Used to convert rotational motion to linear motion, rack and pinion work like wheels on the road. Since the rack is considered to have an infinite diameter, it has a length ratio instead of a speed of transmission ratio. Rack and pinion is a precise solution for precise heavy-duty tasks such as machine shop equipment.
Strain wave Gears
Also called harmonic gears, strain wave gears have an insane speed ratio compared to all of the other gears already mentioned. It is usually paired with high-speed motors because it is efficient, silent, simple, precise, and has a low weight. Because electric motors can speed up without losing precision, strain wave gears are most commonly used in robotics.
Timing gears are special spur gears connected with toothed belts called timing belts. Usually seen in automobiles and industrial machines, timing gears are used to synchronize rotation with precision. However, timing belts being non-metallic limits its range of applications.
Learn More About Gears and Robotics
Hope this article helps you learn about different types of gears and their applications, especially which are relevant to your project. Still have questions? On this page, you can learn more about robotics and relevant components such as gears and electric motors.