Magnetic Levitation : Gear reduction and Calculation
Gear
Gear is a set of toothed wheels that work together to change the speed and torque of the mechanism. There are many types of gears such as spur gear, worm gear, rack and pinion gear, and bevel gear.
Spur gears are two gears that drive each other when the other rotates. If the number of teeth is not equal, the speed and torque will change depending on the ratio.
A pinion gear is a spur gear rotating on a bar with teeth. when spur gear rotates, the bar also moves. The distance it moves depends on the diameter of the spur gear. Rack and pinion gear does not change speed but changes rotational movement to linear.
Bevel gears are similar to spur gears but they are connected at an angle. It changes the axis of rotation.
A worm gear is a spiral and spur gear. When the spiral part rotates, it slowly rotates the spur.
Gear Reduction
As stated above, if the number of teeth on the two gears are not equal, there will be a change in the speed and torque by the ratio of teeth.
If the number of teeth of the input gear is less than the output gear, then the speed will decrease while the torque increases. But if the input has more teeth than output gear, then the speed of output will increase thus decreasing the torque.
For example, the input gear has 20 teeth and output gear has 40 teeth. So we can write the ratio in this format.
(output gear’s teeth : input gear’s teeth)
In this case, 40 : 20 or 2 : 1. This means the output gear rotates once for every 2 input rotation. If the input gear rotates at 100 RPM (rotation per minute) the output would be would decrease by a half. If B is the input, the reduction ratio would be 1 : 2, which means the output gear would rotate twice for every input rotation. If there are more than one pair, the output of the first set would be the input of the second set.
The motor I used in the magnetic levitation project is a motor with gears, so gear calculation is very important in choosing the right motor.
