# How to Build a Weight Pulling Robot

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## Introduction: How to Build a Weight Pulling Robot

In this instructable we will show you the materials and steps in order for you to build and run a weight pulling robot. This was all for an Engineering class project we had to complete at the end of the school year in order to see who could get the best torque and speed ratio to allow the robot to pull as many 5lb. weights as it could.

## Step 1: Materials/Step 1a

You will need these parts for the robot:

1 open ended wrench
2 Hex/Allen wrenches (one large and one small)
2 wire-motors
4 6-32 hex screws
41 8-32 hex screws
6 36-tooth gears
4 12-tooth gears
2 60-tooth gears
4 12.5cm knobby tires/wheels
14 collars (with setscrews)
41 keps nuts
12 flat berings
5 bering blocks
2 30cm squarebars
6 6cm squarebars
2 9-holed holebars
4 chassy rails
(and any other parts you see in the pictures in the next steps that were not included here)

## Step 2: Step 1b

Add the motors to the bottom of the robot.

## Step 3: Step 2

On the bottom of the robot construct gears, motors, and wheels to look like the pictures, connecting the 60t gear to the motor. Make sure the gear ratio for the back wheels is 60:12:36 (5:1:3), and the gear ratio for the front should be 36:36:60 (3:3:5) on both sides starting from the front of the robot. We chose this ratio because the W-output was 175 and the torque on the robot was 1.002, which are both good numbers.

## Step 4: Step 3

Build the wheels of the robot to look like they are in the picture. We decided to use these wheels because we believed (and was later correct) that they would give us a good grip on the surface of the floor it was moving on.

## Step 5: Step 4

Build the body of the robot as shown in the picture.

## Step 6: Step 5

Build the trialer to hold the weights the way it is shown in the pictures.

## Step 7: Step 6

Don't forget to add a fully charged battery to your robot before you turn it on and start testing it.

## Step 8: Step 7

Add one weight onto the trailer and run the shown program. This program should be made in EasyC programming. Afternthe first test, and another 5lb. weight and execute the code again.

## Step 9: Step 8

Write down your data from your tests in a notebook and continue repeating this process until the robot can not pull any more weights.

## Step 10: Step 9

Calculate your angular velocity and the torque output of the robot and write these calculations in your notebook.

## Step 11: Our Original Design

Our original design for the robot looked somewhat similar to the Bad Piggies contraption shown in the picture. After a few tests with this design and with a different gear ratio, we realized it was not the best to use and quickly switched to the current design. The design we have now is, to our knowledge, the best out of all of our other classmate's robots.

## Step 12: Congratulations!

You have now complete the instructable! Have fun with your robot! ;D

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## Discussions

This is cool! How many pounds of weight did your robot end up pulling? Thanks for sharing!