STEM

DC Motor Vs Geared Motor – Explained with Experiments

Last Updated on 20/02/24 0
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Electric motors are one of the finest inventions of the twentieth century. They are the magical little things that harness the power of electricity and make things move! 

There are 2 types of electric motors that we use regularly in our robotics kits and domestic use: DC motor and DC Geared Motor(BO motor as referred in market terms).

We learn all about these 2 motors in the class with hands-on experiments.

Class Summary:

0:40 – What are Motors in general?

Motors are rotating electrical devices that convert electrical energy into mechanical energy. 

1:03 – Which among the dc motor and the bo motor is the strongest?

How to measure the efficiency/strength of these motors?

Is speed the only measure of efficiency? Maybe, it is in a running race. But when it comes to motors the efficiency of a motor is decided based on its applications.

Electric Gear motors(bo motors)are used in applications that require high torque and lower speed like automatic doors, wipers, plates inside a microwave, etc…

bo motor
Geared Motor (BO Motor)

The Electric motor without gears is useful in many applications, like the fan, toy cars, etc.

dc motor
DC Motor

1:40 – Experiment with Havi Elements’ DC motor

    • Connect the power element to the motor element 
    • Then connect the dc motor to the circuit.
    • Attach a wheel to the motor shaft
    • Turn the power on
    • Observe the speed of the wheel

dc vs bo motor
3:38 – Next, repeat the above steps by replacing the dc motor with BO motor 

Observe the speed of the wheel 

5:01 – What’s the observation of the above 2 experiments?

After turning the power off, the BO motor turns off immediately. While the DC motor keeps turning for a few seconds more. We will see why this happens in a while.

6:36 – Moving onto the next Experiment 

While the wheel attached to the motors is turning, touch the wheel with your finger slightly. 

Try this for both the motors.

What did you observe?

The wheel attached to the DC motor stops immediately when touched. 

While the wheel attached to the Bo motor keeps moving with a little resistance. 

7:39 – Why does this happen and which one is the strongest?

9:23 – Before we answer those questions, we need to know how electric motors work. Explained in detail there.

9:42 – Now, what makes the BO motor strong enough to keep moving even when touched? 

Let’s understand that with an analogy. If you were to hit a sofa with your hands and a friend would hit the same sofa with a stick. Who do you think would dust the sofa well?  Easy much? Your friend with the help of the stick leverages his strength. 

11:10 – Similarly, the BO motor has gears attached to the motor. The addition of a gear head to a motor increases the torque output. 

11:38 – What is Torque though? 

Torque is the rotational power of a motor. In simpler words, Torque is a type of force that makes things move in angular instead of linear. It’s just the rotational equivalent of force. Example: What is applied to push a box from point a to b is force. What is applied to pedal a cycle is a torque.

Unit of torque: Newton–meter (N-m).

Formula of Torque: τ = r x F 

That is the force times radius of the circle formed by the rotational force.

13:18 – The same principle of torque applies to cars too. Having learned about it now, In which gear does a car run the fastest? 

The highest gear, be it the 4th or the 5th gear.

14:20 – In which gear the car can climb a slope efficiently?

The lowest gear, 1st or 2nd gear.

15:50 – What do gears look like?

dc vs bo motor
17:15 – In cars, the first gear means less speed and more power 

While the last gear means more speed and less power.

18: 03 – Same is the case with motors, BO motor with gears has more torque(power), hence less speed. But the DC motor which does not have gears has more speed and less power.

That was a pretty fruitful class, isn’t it? A class in electronics, physics, AND Driving!

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