Answers.Body: <p>I have received this set as part of the <a href="https://bricks.meta.stackexchange.com/questions/621/2024-q3-activity-support">2024 Q3 Activity Support</a>, so now I can provide a sufficiently sourced answer. Spoiler alert: the obvious suspicion was true - the tires are to balance the Globe. But how much are they needed and how well do they work?</p>
  <p>To find it out, I first built the Globe as intended, with all four tires anchored deep in the mantle. Then gave it a good spin, long enough to consider the position the Globe ground to an inevitable stop a truly random outcome, determined only by the weight distribution of the model. Then I noted the plate that was directly above the &quot;The Earth&quot; nameplate.</p>
  <p>Then I repeated the above process <sub>(starting from the spin, I certainly didn't rebuild the Globe for each spin!)</sub> a nice round hundred times. Here are the results:</p>
  <div class="s-table-container"><table class="s-table">
  <thead>
  <tr>
  <th>Equatorial tile above the nameplate</th>
  <th># of spins</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>East Atlantic Ocean</td>
  <td>6</td>
  </tr>
  <tr>
  <td>West Atlantic Ocean</td>
  <td>4</td>
  </tr>
  <tr>
  <td>East South America</td>
  <td>8</td>
  </tr>
  <tr>
  <td>West South America</td>
  <td>9</td>
  </tr>
  <tr>
  <td>East Pacific Ocean</td>
  <td>8</td>
  </tr>
  <tr>
  <td>Mid East Pacific Ocean</td>
  <td>11</td>
  </tr>
  <tr>
  <td>Mid Pacific Ocean</td>
  <td>8</td>
  </tr>
  <tr>
  <td>Mid West Pacific Ocean</td>
  <td>5</td>
  </tr>
  <tr>
  <td>West Pacific Ocean</td>
  <td>1</td>
  </tr>
  <tr>
  <td>East Polynesia</td>
  <td>4</td>
  </tr>
  <tr>
  <td>Mid Polynesia</td>
  <td>7</td>
  </tr>
  <tr>
  <td>West Polynesia</td>
  <td>2</td>
  </tr>
  <tr>
  <td>East Indian Ocean</td>
  <td>7</td>
  </tr>
  <tr>
  <td>West Indian Ocean</td>
  <td>8</td>
  </tr>
  <tr>
  <td>Mid Africa</td>
  <td>5</td>
  </tr>
  <tr>
  <td>West Africa</td>
  <td>7</td>
  </tr>
  </tbody>
  </table></div>
  <p>For reference, with 16 equatorial plates, each plate should have come up exactly 6.25 times. In hindsight, I should probably have spun the Globe an integer multiple of 16 times. Anyway, it can still be beautifully seen that the distribution is quite far from the ideal one expected from a uniform or at least a well-balanced globe.</p>
  <p>Having &quot;Mid East Pacific Ocean&quot; come in at first place means the plate with the &quot;Atlantic Ocean&quot; tile is the heaviest and on the opposite side, &quot;East Polynesia&quot; directly north of the &quot;Australia&quot; tile is the lightest - with the tires in place as planned.</p>
  <h2>But what happens when the tires are removed?</h2>
  <p>The results quickly showed why this was a fool's errand, but here are the initial data points from the first 25 spins:</p>
  <div class="s-table-container"><table class="s-table">
  <thead>
  <tr>
  <th>Equatorial tile above the nameplate</th>
  <th># of spins</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>East Atlantic Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>West Atlantic Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>East South America</td>
  <td>18</td>
  </tr>
  <tr>
  <td>West South America</td>
  <td>6</td>
  </tr>
  <tr>
  <td>East Pacific Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>Mid East Pacific Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>Mid Pacific Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>Mid West Pacific Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>West Pacific Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>East Polynesia</td>
  <td></td>
  </tr>
  <tr>
  <td>Mid Polynesia</td>
  <td></td>
  </tr>
  <tr>
  <td>West Polynesia</td>
  <td>1</td>
  </tr>
  <tr>
  <td>East Indian Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>West Indian Ocean</td>
  <td></td>
  </tr>
  <tr>
  <td>Mid Africa</td>
  <td></td>
  </tr>
  <tr>
  <td>West Africa</td>
  <td></td>
  </tr>
  </tbody>
  </table></div>
  <p>Clearly, this is not just &quot;not 100% fair&quot;, like the above table provers for the <em>tired</em> version, but beyond broken. In fact, the Globe without its tires can't even stay in any other orientation, as the combined weight of the European and African <em>plates</em> pulls that hemisphere towards the arched support. The only fluke was when the heavier side somehow ended up on the highest point, in an unstable equilibrium, which nevertheless was attained due to the frictional forces overcoming the moment arm of the overweight plates.</p>
  <p>So that is the purpose of the tires: to balance the model so that it can actually hold any orientation.</p>
  <p>Otherwise, it just settles with the heavier side down:</p>
  <p><a href="https://i.sstatic.net/6YfFruBM.gif" rel="nofollow noreferrer"><img src="https://i.sstatic.net/6YfFruBM.gif" alt="GIF of spinning the tireless Globe, which grinds to a halt and changes direction at the end" /></a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-10-28T15:45:27.530Z
Answers.LastActivityDate: 2024-10-29T06:44:21.067Z
Answers.LastEditDate: 2024-10-29T06:44:21.067Z
Answers.UserDisplayName: zovits
Body: <p>I just finished building The Globe (set #21332), and I'm curious what the purpose of the four rubber tires on the interior of the model is (highlighted with red box):</p>
  <p><a href="https://i.sstatic.net/Q9L0O.jpg" rel="noreferrer"><img src="https://i.sstatic.net/Q9L0O.jpg" alt="page from instruction manual with tires in question highlighted" /></a></p>
  <p>I had hoped that towards the end of the construction process their purpose would somehow be revealed, but sadly that didn't happen.</p>
  <p>My best guess is that they are some sort of counterweight to prevent the globe from always settling into a certain orientation, but due to the tilted axle and the overall weight of the rotating part there seems to be enough friction to prevent the globe from moving by itself. Also, the tires, though somewhat heavier than regular Lego parts, don't seem to be adding a significant amount of weight.</p>
  <p>My second guess was that the tires are some kind of assembly aid that would help with handling the (admittedly somewhat unwieldy) globe in a later construction step. However, I did not encounter any point in the assembly process where those tires would have been helpful in some way.</p>
  <p>Does anyone know what the actual purpose of these elements is?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2023-05-23T14:08:52.307Z
Comments.Text: It's indeed a counterweight for the landmass (plates and tiles) missing in the pacific part of the globe. Friction can vary on how tightly the model was built, or perhaps the globe wobbles slightly when motorized. Or perhaps the designers added this just in case...
Comments.UserDisplayName: Michael Verschaeve
Tags: <sets><design><advanced-models>
Title: Purpose of the four rubber tires in The Globe set (21332)
UserDisplayName: raner
ThreadText: # Purpose of the four rubber tires in The Globe set (21332)
  
  (Asked by: username_0 on 2023-05-22)
  
  I just finished building The Globe (set #21332), and I'm curious what the purpose of the four rubber tires on the interior of the model is (highlighted with red box):
  
  [![page from instruction manual with tires in question highlighted](https://i.sstatic.net/Q9L0O.jpg)](https://i.sstatic.net/Q9L0O.jpg)
  
  I had hoped that towards the end of the construction process their purpose would somehow be revealed, but sadly that didn't happen.
  
  My best guess is that they are some sort of counterweight to prevent the globe from always settling into a certain orientation, but due to the tilted axle and the overall weight of the rotating part there seems to be enough friction to prevent the globe from moving by itself. Also, the tires, though somewhat heavier than regular Lego parts, don't seem to be adding a significant amount of weight.
  
  My second guess was that the tires are some kind of assembly aid that would help with handling the (admittedly somewhat unwieldy) globe in a later construction step. However, I did not encounter any point in the assembly process where those tires would have been helpful in some way.
  
  Does anyone know what the actual purpose of these elements is?
  
  **Tags:** sets, design, advanced-models
  
  > **Comments:**
  > **username_1**: It's indeed a counterweight for the landmass (plates and tiles) missing in the pacific part of the globe. Friction can vary on how tightly the model was built, or perhaps the globe wobbles slightly when motorized. Or perhaps the designers added this just in case...  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_2 on 2024-10-28. Score: 5
  
  I have received this set as part of the [2024 Q3 Activity Support](https://bricks.meta.stackexchange.com/questions/621/2024-q3-activity-support), so now I can provide a sufficiently sourced answer. Spoiler alert: the obvious suspicion was true - the tires are to balance the Globe. But how much are they needed and how well do they work?
  
  To find it out, I first built the Globe as intended, with all four tires anchored deep in the mantle. Then gave it a good spin, long enough to consider the position the Globe ground to an inevitable stop a truly random outcome, determined only by the weight distribution of the model. Then I noted the plate that was directly above the "The Earth" nameplate.
  
  Then I repeated the above process (starting from the spin, I certainly didn't rebuild the Globe for each spin!) a nice round hundred times. Here are the results:
  
  | Equatorial tile above the nameplate | # of spins |
  | --- | --- |
  | East Atlantic Ocean | 6 |
  | West Atlantic Ocean | 4 |
  | East South America | 8 |
  | West South America | 9 |
  | East Pacific Ocean | 8 |
  | Mid East Pacific Ocean | 11 |
  | Mid Pacific Ocean | 8 |
  | Mid West Pacific Ocean | 5 |
  | West Pacific Ocean | 1 |
  | East Polynesia | 4 |
  | Mid Polynesia | 7 |
  | West Polynesia | 2 |
  | East Indian Ocean | 7 |
  | West Indian Ocean | 8 |
  | Mid Africa | 5 |
  | West Africa | 7 |
  
  For reference, with 16 equatorial plates, each plate should have come up exactly 6.25 times. In hindsight, I should probably have spun the Globe an integer multiple of 16 times. Anyway, it can still be beautifully seen that the distribution is quite far from the ideal one expected from a uniform or at least a well-balanced globe.
  
  Having "Mid East Pacific Ocean" come in at first place means the plate with the "Atlantic Ocean" tile is the heaviest and on the opposite side, "East Polynesia" directly north of the "Australia" tile is the lightest - with the tires in place as planned.
  
  ## But what happens when the tires are removed?
  
  The results quickly showed why this was a fool's errand, but here are the initial data points from the first 25 spins:
  
  | Equatorial tile above the nameplate | # of spins |
  | --- | --- |
  | East Atlantic Ocean |  |
  | West Atlantic Ocean |  |
  | East South America | 18 |
  | West South America | 6 |
  | East Pacific Ocean |  |
  | Mid East Pacific Ocean |  |
  | Mid Pacific Ocean |  |
  | Mid West Pacific Ocean |  |
  | West Pacific Ocean |  |
  | East Polynesia |  |
  | Mid Polynesia |  |
  | West Polynesia | 1 |
  | East Indian Ocean |  |
  | West Indian Ocean |  |
  | Mid Africa |  |
  | West Africa |  |
  
  Clearly, this is not just "not 100% fair", like the above table provers for the *tired* version, but beyond broken. In fact, the Globe without its tires can't even stay in any other orientation, as the combined weight of the European and African *plates* pulls that hemisphere towards the arched support. The only fluke was when the heavier side somehow ended up on the highest point, in an unstable equilibrium, which nevertheless was attained due to the frictional forces overcoming the moment arm of the overweight plates.
  
  So that is the purpose of the tires: to balance the model so that it can actually hold any orientation.
  
  Otherwise, it just settles with the heavier side down:
  
  [![GIF of spinning the tireless Globe, which grinds to a halt and changes direction at the end](https://i.sstatic.net/6YfFruBM.gif)](https://i.sstatic.net/6YfFruBM.gif)
  
  
  ---
  
  