1. 1.9: Drive Train

2. 1.9: Drive Train A robotic drive train is a system of components
motors
gears
wheels
It allows the robot to move from one point to another. These components can be assembled in many different ways to propel the robot.

3. Motors
How Motors Work A motor converts electrical energy into mechanical energy.

4. Motors
When supplied with power the motor produces physical motion. Power travels through electrical wires to the motor.
The motor drives an output shaft that rotates, translating the electrical power into rotational motion.

5. Motors

6. Motors
Vex Kit Motor The Vex robotics system comes with a continuous 2-wire motor.
This motor can rotate 360 degrees continuously when electrical power is applied to the motor. Continuous motors are used for drive trains, gear boxes or any application that requires the shaft of the motor to rotate continuously.

7. Motors
Motor Controller The motor controller allows the robot to drive a 2-wire motor using a PWM (Pulse Width Modulation) standard. You will learn more about PWM later.

8. Motors
Motor Coupler Each motor has a removable coupler and post. The coupler acts as a spacer, and prevents the motor from stalling and protects the internal gears of the motor from damage.

9. Gears
Gears transmit motion and force in machines. They come in a variety of shapes and sizes. The teeth of two gears engage each other to transfer motion and force from one gear to the next. This engagement is called meshing and can affect the rotation of the gears in the following ways: change the speed reverse the direction change the axis

10. Gears
There are a variety of different types of gears, which we will cover in a later unit. The most common type of gear is a spur gear. You will use spur gears supplied with the Vex kit.

11. Gears

12. Gears
Gears
Vex Kit Gears There are four gear sizes included in the Vex starter kit: 12-tooth 36-tooth 60-tooth 84-tooth

13. Wheels
A wheel is a simple machine consisting of a circular frame, with spokes or a solid disk, which can rotate on a shaft or an axle. Wheels come in many different sizes. The bigger the wheel, the further it will roll with every revolution of the axle.

14. Wheels
There are three different types of wheels provided in the Vex starter kit:
A knobby tire provides excellent traction

15. Wheels
An all-purpose tire with a flat tread.

16. A removable tire with a plastic hub which can be used as a caster.

17. Bearings
A bearing is a component used to reduce friction in a machine, commonly used with rotating parts like wheels, gears and shafts.

18. Bearings
The flat bearing has three holes in it and is designed to mount onto all of the Vex hardware. Two of the holes are typically used for mounting screws and the third hole is used to support a shaft for an axle or gear.

19. Bearings
The bearing block has two mounting holes and a third hole in the middle of the bearing that is oriented at a right angle from the mounting holes. These bearings are typically used as a pivot for a variety of mechanisms you can build.

20. Bearings
Both types of bearings provide round plastic holes for the square shafts to rotate in. This greatly reduces the amount of friction in the system

21. Shafts and Collars
Shafts are the connecting link between the motors, gears and wheels in a drive train.

22. Shafts and Collars
The shafts provided in your Vex kit are 1/8" square bars. All of the gears and wheels in the kit have a square hole to fit this size shaft. The square design prevents the gear or wheel from rotating freely on the shaft. This is why the bearings play such an important role in this design system.

23. Shafts and Collars
Collars with setscrews prevent the shafts from coming out of the motors, gears and wheels.

24. Shafts and Collars
It is critical to design your robot to withstand the rigors of the robotic challenge without falling apart. Proper use and careful placement of the collars on the shafts will enable you to meet this aspect of the challenge

25. Bringing it All Together
The drive train is the most important system in your robot’s design. A drive train must be robust and durable. An unreliable drive train could leave your robot motionless, rendering useless all the other design innovations you engineered into it. Test your drive train repeatedly to work out any bugs in the system before entering a competition with it.

26. Troubleshooting notes:
Friction is your drive train's worst enemy and should be your first consideration when troubleshooting. Wear and tear on the robot will cause bearings and shafts to come loose, which could result in mechanical binding. Always rotate the wheels in your drive train by hand and verify that both sides feel roughly the same. If one side is harder to rotate than the other, investigate all the components on that side to try to find the problem.