In this tutorial, we would drive the scissors mechanism and there are a number of rules that we must follow
- 22 Mar 2017
- LEGO MINDSTORMS, LEGO MINDSTORMS EV3
- FIRST LEGO League, Attachments, EV3, Attachments, Construction, Classes with students, FLL
With the motor in the centre of the robot, we must use a system of gear to transfer the power. The final driving wheel must be as small as possible. In this case, we are using 40 teeth gear wheels so for driving we must use the 8 teeth LEGO gear wheel. This will increase the torque and will reduce the speed because in lifting we must increase the torque and power to be able to lift the robot.
Changing gear orientations and direction of axles
It would be necessary to change the gear orientation and the direction in which the axles rotate. There are plenty of resources about this and you could find them at:
or generally just search for Gear Orientation.
Our next step is to actually drive this scissor mechanism. And for driving there are some rules that we must follow.
We have the robot, we have the scissor mechanism and we should place one mechanism at each side of the robot. And then when we rotate with the gear wheel we would lift the robot. It's an interesting question: Where do we place this axle? Is it at the back of the robot at this side? Is it at the front of the robot? The important thing is that to transfer the power from the motors that are right here in the center of the Box Robot to transfer the power from the motors to our scissor mechanism we'll need some form of a gear system - gears that are changing directions, gears that are increasing the ratio or decreasing the ratio. So, it's a mechanism of gears. At the end when we get to the final wheel this is this large wheel here we should always try to drive this wheel with a small gear wheel - 8 teeth gear wheel. And this will allow us to go for power and for torque which is important when lifting heavy objects and not that much for speed. So, the end wheel is a small 8 teeth wheel that is driving the large 40 teeth wheel.
Again, the advantage when using a small 8 teeth gear wheel driving a large 40 teeth gear wheel is that you are going for torque. And this is what you want to get at the end for lifting a heavy object. But you reduce the speed. So, lifting the robot will be slower. How slow? We should see this as an end result.
Also when transferring the power from the axles that are at the front of the robot to these scissor mechanisms that are at the side of the robot we must change the gear orientation. What I'll try to do is to add in the course links for a number of videos for changing the gear orientation - the orientation of gears and changing the direction of the axles. Check them out before moving forward to the course because some of the next tasks are actually changing the orientation of different gears.
Courses and lessons with this Tutorial
This Tutorial is used in the following courses and lessons