1. Mechanical drive mechanisms
By Robert Wall, Christopher Lockwood, Joe Gregson Lockie

2. Ball screws
What is a ball screw!!

3. Chain/ Belt drives

4. Chain/Belt drives Chain drive Belt drive
A chain drive is a way of transmitting power from one place to another. There are three main functions which a chain belt can operate:
1. Transmitting power
2.Conveying materials
3.Timing purposes
Advantages
chains don’t slip like belt drives
There is no power loss due to slippage, making them more efficient
They can operate effectively at high temperatures
Disadvantages
Chains require frequent lubrication
Chains are very noisy and can cause vibration within the machine
Chain drives cannot be used where the drive must slip
A belt drive is a method of transferring rotary motion between two shafts. A belt drive includes one pulley on each shaft and one or more continuous belts over the two pulleys.
Power transmission belts are available in several types: flat belts, V-belts, synchronous belts, and multi-ribbed belts.
When considering belt driven machines you have to take in environmental conditions such as:
Exposure to oil and grease
range of operating temperatures
Sunlight
Advantages
Wide range of speeds
No lubrication needed
Single belt drives will accept more misalignment than chain drives
Disadvantages
Belts cannot be used where exact timing or speed is required because slippage does occur
Belts are easily damaged by oil, grease, abrasives, some chemicals
Belts can be noisy; also loose or worn belts can be a major cause of machinery vibration

5. Reduction Gears in Robots
Understanding Gear Reduction

6. What is it and why does it work?
What are they?
Gears of different sizes connected together.
Used for speed reduction in general whether its used in traditional gear setups, chain and sprockets, or belts.
Used in different areas of a robot.
Focus of this information will
be mainly on the drive train
(The most important part)

7. Distance covered by wheel in 1 rotation = Circumference of the wheel
Understanding how and why they work
Gear reduction involves using gears/sprockets/pulleys of two or more different size that work together.
Different sizes of wheels have different circumferences, thus, the distance travelled for one full rotation would be different.
Distance covered by wheel in 1 rotation = Circumference of the wheel

8. As you can see in the 2 pictures above, the general rule is shown:
Examples
As you can see in the 2 pictures above, the general rule is shown:
The larger the diameter of the wheel, the larger the distance that’s covered in one full rotation. Double the diameter of a wheel and you also double the distance covered.

9. Why they are used
Example: Most DC motors spin at well over 1000 rpm and some even spin at over 50,000 rpm. If we had a robot motor that spun at 3000 rpm and attached a 6 inch wheel, that wheel would theoretically be able to move the robot at almost 54 Miles Per Hour! This is obviously far too fast! Speed of a wheel can be found by: Diameter (inches) x RPM 336

10. This is where reduction gears come into play
This is where reduction gears come into play. We need to reduce the speed so we have more overall control of the robots movements by using 2 or more different sized wheels.

11. Advantages and Disadvantages
More manageable robot speed
Less work for the motor
More torque
(inversely proportional to the amount of reduction created. Example: 4:1 gear box moves the bot ¼ the speed but has 4x the torque – More pulling/pushing power)
Loss of speed (debatable)
More weight for the gear box