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  Course: Functions & Features
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Motors Get your LEGO moving! From Wind Up to Electric - Learn what it takes to add motion to your Models.  
What is a motor? A motor is a certain kind of machine that takes electrical energy and converts it into mechanical energy. Adding a motor to your LEGO model can give it realistic functions - as part of a large moving sculpture or the source of movement for a vehicle, motors can bring your LEGO model to life! The LEGO company makes several kinds of motors, so you can choose the motor that works best with your creation, whether it is a robotic gripping arm, a motorbike that pops wheelies, or a ball kicker for your soccer set (so you can save your hands to practice being goalie).
Here’s the wind-up… The windup motor, used in set 4093, uses your energy to make the model move. When you wind the motor up, your own body’s energy is stored in a spring in the motor. Upon release, the spring unwinds and the energy goes through a gear train which bumps up the number of output revolutions by 2.5X. This means if you wind the input shaft 6 times, the output shaft will unwind 15 times. Of course, as we learned in the lesson on Gearing, this all comes at the price of torque reduction. The torque on the output shaft for the wind-up motor is about 1.2 newtons/cm. You can use it to make things spin and wiggle. It is not one of the most powerful motor solutions, but if you gear it down, you will end up with a more usable amount of force. Gearing it down will of course reduce your overall run time and speed. It’s all about power Power is equal to force applied over a distance, divided by time. Let’s say you move your leg and kick a ball. Your leg moves through a set distance (the swing of your leg), applies force to the ball (when your toe hits it) and the ball rolls forward 5 feet. In a moment, all movement stops. Then let’s say you applied 20lbs of force (one leg casually swinging at the ball) over 1 foot (the distance where your toe is actually touching the ball) for .5 seconds (the time to cover that distance). If you kick the ball harder, the time you are touching the ball is similar as is the distance over which you apply the force, but the force applied is much higher. Thus you have increased the power output. Electric motors For increased power, let’s look at the electric motor from set 4094. Compared to the 1.2 N/cm of the wind-up motor, you can now have up to 9.5 N/cm. The electric motor also has an operating range of around 500rpm, or 5 times the range of the wind-up motor. It’s a substantial increase, but there is a penalty for all this power: batteries. Batteries will need to be built into your model, or your model will need to be connected to them via a wire. Added weight will take a bit of the power away from the driving mechanism if it is a moving model, but if it is a stationary model then it is not such a big deal. Sometimes you don’t want to wind a motor, or turn your model on and off, or manually change direction, and in these cases you have another power option: the smart motor! Featured in set 4093, this little machine gives you the ability to record movements and play them back automatically! Now you can make your model do what you want when you want. You want it to go slow? Spin it slowly while you are programming it. Is speed a need? Spin the shaft fast while the motor is “recording” and that’s just what you’ll get. To get the motor’s output to go where power is needed, you’ll need to use a combination of gears, axles and pulleys. Just remember that the more components you put between the motor and the powered object, a) the more likely they are to break (because the more moving parts you have, the more changes there are for things to go wrong); and b) the more friction you are going to have in the system (and that means less available power). Be careful to avoid stalling and overloading when using electric motors. Motors work thanks to the miracle of electrical energy which is converted into motion. However, if motion cannot be made, then energy becomes heat, which can damage your motor. If the motor is moving slowly, and you have not made any gear reductions, you may be overloading it. Try to gear down the motor to make more torque and thus move the weight. There are a few other things to look out for when using electric motors:
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