Answers.Body: <p>After receiving the rover via the <a href="https://bricks.meta.stackexchange.com/q/614/3631">2024 Q1 Activity Support</a> program, I set about to answer the question. Using parts from a <a href="https://brickset.com/sets/42065-1/RC-Tracked-Racer" rel="nofollow noreferrer">42065: RC Tracked Racer</a> and a <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?S=88004-1#T=S&amp;O=%7B%22iconly%22:0%7D" rel="nofollow noreferrer">PF servo motor</a> to keep the costs and complexity low I started by emptying the crew compartment to make room for the steering assembly, figuring there'd be no need for facilities for humans if the rover is remotely operated.</p>
  <p>After hitting <a href="https://bricks.stackexchange.com/questions/18609/how-to-troubleshoot-an-inert-power-functions-servo-motor">a snag with the servo motor</a>, the plan changed to use a clutch for protecting the model and one of the <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=58120c01&amp;idColor=86#T=C&amp;C=86" rel="nofollow noreferrer">PF M motors for steering</a>. The first test with <a href="https://bricks.stackexchange.com/questions/17547/has-anyone-else-had-problems-with-the-tail-rotor-drive-shaft-on-the-lego-airbus/17548#17548">the clutch mechanism</a> seen in the <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?S=42145-1#T=S&amp;O=%7B%22iconly%22:0%7D" rel="nofollow noreferrer">42145 Airbus H175 Rescue Helicopter</a></p>
  <p><a href="https://i.sstatic.net/5XNFjPHO.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/5XNFjPHO.jpg" alt="Exploded view of the first clutch idea during testing" /></a></p>
  <p>proved the need for a setup with a higher slipping torque, so a <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=60c01&amp;name=Technic,%20Gear%2024%20Tooth%20Clutch&amp;category=%5BTechnic,%20Gear%5D#T=C" rel="nofollow noreferrer">Technic, Gear 24 Tooth Clutch</a> has been chosen to proceed with.</p>
  <p>Seeing the need for high torque, the power transmission from the motor to the steering axle was planned with a pair of <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=32072#T=C" rel="nofollow noreferrer">Technic Knob Cog / Gear / Wheel with Axle Hole (+ Orientation)</a> pieces. Finally, a 1:3 reduction gearing was added to allow for precision steering and to produce the torque required to turn the rubber wheels.</p>
  <p><a href="https://i.sstatic.net/HhQ4CDOy.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/HhQ4CDOy.jpg" alt="The steering sub-assembly" /></a></p>
  <p>This was simplified later to eliminate the obvious redundancy still visible in this photo, see the final assembly stage for the latest version.</p>
  <p>For the drive motor, a rear axle was constructed with the same knob gear (thanks to the clear round holes leading to the wheel hubs and no obstructions on the suspension), and a motor was mounted (here just temporarily) on some Technic-System bridge pieces:</p>
  <p><a href="https://i.sstatic.net/M6AQP6rp.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/M6AQP6rp.jpg" alt="Rear axle under development" /></a>
  <a href="https://i.sstatic.net/FyFjR9xV.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/FyFjR9xV.jpg" alt="Motor mounting detail" /></a></p>
  <p>This was enough to turn the wheels, albeit only in the upside-down orientation shown in the photos. As soon as the rover was resting on its wheels, the torque of the motor proved woefully inadequate to move the whole mass.</p>
  <p>So for the next attempt a 1:8 reduction was added by changing the knob gears for the combination of a worm gear and an 8-tooth gear, while also strengthening the bracing around the transmission and moving the motor mounting a bit to the side and one unit further from the chassis (this sadly reduced the ground clearance significantly):</p>
  <p><a href="https://i.sstatic.net/Gsibv6BQ.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Gsibv6BQ.jpg" alt="The reworked motor mounting with the worm gear reductor" /></a></p>
  <p>The battery box found a snug hiding place between the first and second axles (eliminating the wheelbase-changing function as collateral damage):</p>
  <p><a href="https://i.sstatic.net/bZNAY60U.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/bZNAY60U.jpg" alt="The mounted battery box in the undercarriage" /></a></p>
  <p>The steering motor was mounted on a plate held in the crew bay by several <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=89678#T=C" rel="nofollow noreferrer">Technic pin 1/2s</a> (the surplus seen here in grey):</p>
  <p><a href="https://i.sstatic.net/vTQslTOo.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/vTQslTOo.jpg" alt="The steering subassembly on a plate in the crew compartment" /></a></p>
  <p>Finally, the IR receiver was attached to the cargo area, with the cables routed via the airlock and a cutout in the payload bed:</p>
  <p><a href="https://i.sstatic.net/6HXQT7YB.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/6HXQT7YB.jpg" alt="The finished mod" /></a></p>
  <p>Possible avenues for improvement would include:</p>
  <ul>
  <li>Using stronger motors for more torque for both steering and driving</li>
  <li>Mounting the motors in a more Technic-compliant and elegant way</li>
  <li>Using a more modern RC architecture</li>
  <li>Hiding the modifications better to keep more of the original functions, aesthetics, and playability.</li>
  </ul>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-05-30T07:34:26.117Z
Answers.LastActivityDate: 2024-05-30T07:34:26.117Z
Answers.UserDisplayName: zovits
Body: <p>The <a href="https://www.lego.com/de-de/product/mars-crew-exploration-rover-42180" rel="nofollow noreferrer">42180 Mars Exploration Rover</a> has a sturdy Technic frame with plenty of empty space - how could it be fitted with driving and steering motors for remote-controlled driving?</p>
  
Tags: <technic><motor><remote-control><set-modification>
Title: How can the 42180 Mars Exploration Rover be motorized?
UserDisplayName: zovits
ThreadText: # How can the 42180 Mars Exploration Rover be motorized?
  
  (Asked by: username_0 on 2024-05-30)
  
  The [42180 Mars Exploration Rover](https://www.lego.com/de-de/product/mars-crew-exploration-rover-42180) has a sturdy Technic frame with plenty of empty space - how could it be fitted with driving and steering motors for remote-controlled driving?
  
  **Tags:** technic, motor, remote-control, set-modification
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_0 on 2024-05-30. Score: 2 | Accepted answer
  
  After receiving the rover via the [2024 Q1 Activity Support](https://bricks.meta.stackexchange.com/q/614/3631) program, I set about to answer the question. Using parts from a [42065: RC Tracked Racer](https://brickset.com/sets/42065-1/RC-Tracked-Racer) and a [PF servo motor](https://www.bricklink.com/v2/catalog/catalogitem.page?S=88004-1#T=S&O=%7B%22iconly%22:0%7D) to keep the costs and complexity low I started by emptying the crew compartment to make room for the steering assembly, figuring there'd be no need for facilities for humans if the rover is remotely operated.
  
  After hitting [a snag with the servo motor](https://bricks.stackexchange.com/questions/18609/how-to-troubleshoot-an-inert-power-functions-servo-motor), the plan changed to use a clutch for protecting the model and one of the [PF M motors for steering](https://www.bricklink.com/v2/catalog/catalogitem.page?P=58120c01&idColor=86#T=C&C=86). The first test with [the clutch mechanism](https://bricks.stackexchange.com/questions/17547/has-anyone-else-had-problems-with-the-tail-rotor-drive-shaft-on-the-lego-airbus/17548#17548) seen in the [42145 Airbus H175 Rescue Helicopter](https://www.bricklink.com/v2/catalog/catalogitem.page?S=42145-1#T=S&O=%7B%22iconly%22:0%7D)
  
  [![Exploded view of the first clutch idea during testing](https://i.sstatic.net/5XNFjPHO.jpg)](https://i.sstatic.net/5XNFjPHO.jpg)
  
  proved the need for a setup with a higher slipping torque, so a [Technic, Gear 24 Tooth Clutch](https://www.bricklink.com/v2/catalog/catalogitem.page?P=60c01&name=Technic,%20Gear%2024%20Tooth%20Clutch&category=%5BTechnic,%20Gear%5D#T=C) has been chosen to proceed with.
  
  Seeing the need for high torque, the power transmission from the motor to the steering axle was planned with a pair of [Technic Knob Cog / Gear / Wheel with Axle Hole (+ Orientation)](https://www.bricklink.com/v2/catalog/catalogitem.page?P=32072#T=C) pieces. Finally, a 1:3 reduction gearing was added to allow for precision steering and to produce the torque required to turn the rubber wheels.
  
  [![The steering sub-assembly](https://i.sstatic.net/HhQ4CDOy.jpg)](https://i.sstatic.net/HhQ4CDOy.jpg)
  
  This was simplified later to eliminate the obvious redundancy still visible in this photo, see the final assembly stage for the latest version.
  
  For the drive motor, a rear axle was constructed with the same knob gear (thanks to the clear round holes leading to the wheel hubs and no obstructions on the suspension), and a motor was mounted (here just temporarily) on some Technic-System bridge pieces:
  
  [![Rear axle under development](https://i.sstatic.net/M6AQP6rp.jpg)](https://i.sstatic.net/M6AQP6rp.jpg)
  [![Motor mounting detail](https://i.sstatic.net/FyFjR9xV.jpg)](https://i.sstatic.net/FyFjR9xV.jpg)
  
  This was enough to turn the wheels, albeit only in the upside-down orientation shown in the photos. As soon as the rover was resting on its wheels, the torque of the motor proved woefully inadequate to move the whole mass.
  
  So for the next attempt a 1:8 reduction was added by changing the knob gears for the combination of a worm gear and an 8-tooth gear, while also strengthening the bracing around the transmission and moving the motor mounting a bit to the side and one unit further from the chassis (this sadly reduced the ground clearance significantly):
  
  [![The reworked motor mounting with the worm gear reductor](https://i.sstatic.net/Gsibv6BQ.jpg)](https://i.sstatic.net/Gsibv6BQ.jpg)
  
  The battery box found a snug hiding place between the first and second axles (eliminating the wheelbase-changing function as collateral damage):
  
  [![The mounted battery box in the undercarriage](https://i.sstatic.net/bZNAY60U.jpg)](https://i.sstatic.net/bZNAY60U.jpg)
  
  The steering motor was mounted on a plate held in the crew bay by several [Technic pin 1/2s](https://www.bricklink.com/v2/catalog/catalogitem.page?P=89678#T=C) (the surplus seen here in grey):
  
  [![The steering subassembly on a plate in the crew compartment](https://i.sstatic.net/vTQslTOo.jpg)](https://i.sstatic.net/vTQslTOo.jpg)
  
  Finally, the IR receiver was attached to the cargo area, with the cables routed via the airlock and a cutout in the payload bed:
  
  [![The finished mod](https://i.sstatic.net/6HXQT7YB.jpg)](https://i.sstatic.net/6HXQT7YB.jpg)
  
  Possible avenues for improvement would include:
  
  * Using stronger motors for more torque for both steering and driving
  * Mounting the motors in a more Technic-compliant and elegant way
  * Using a more modern RC architecture
  * Hiding the modifications better to keep more of the original functions, aesthetics, and playability.
  
  
  ---
  
  