Answers.Body: <p>I would try a <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=32556#T=S&amp;O=%7B%22iconly%22:0%7D" rel="nofollow noreferrer">3L low-friction Technic pin</a>, whose middle section is threaded through the pin holes of two <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=6632#T=S&amp;O=%7B%22iconly%22:0%7D" rel="nofollow noreferrer">half-width liftarms</a> (these would be joined to the trailers), and the ends capped with 1L &quot;liftarms&quot; (aka. <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=18654" rel="nofollow noreferrer">Technic cylinders or spacers</a>) and plugging some bars (e.g. <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=93094pb03#T=S&amp;O=%7B%22iconly%22:0%7D" rel="nofollow noreferrer">a lipstick</a>) in the end holes to prevent the spacers from sliding off.</p>
  <p>A shorter option would be to fix a <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=32002" rel="nofollow noreferrer">3/4 Technic pin</a> in a <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=6632#T=S&amp;O=%7B%22iconly%22:0%7D" rel="nofollow noreferrer">half-width liftarm</a> on the shorter end, attaching another one (or two) on the other end and locking both sides with any suitable 3.18 mm bar - maybe with a single piece across the whole pin.</p>
  
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Answers.CreationDate: 2024-08-02T09:56:19.257Z
Answers.Text: Interesting. Your solution takes lengthwise slightly less space (using a 5L axle on my variant) as mine, but the width is a minimum of 3L and mine would fit in 2L (provided the mounting to the vehicle can be done in the vertical plane). A 2L narrow bar would also work instead of a lipstick piece (lipsticks are not very common pieces in my experience.)
Answers.UserDisplayName: Tonny
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Answers.CreationDate: 2024-12-12T07:24:28.313Z
Answers.Text: This could be a good way of creating the rotation joint, but the half-width liftarms does not provide any secure way of attaching to the trailers. The half-width axle holes would likely provide too little grip. Is there another piece that could be used instead?
Answers.UserDisplayName: sondre99v
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Answers.Text: @sondre99v The half-width liftarms could be quite long and could extend in different directions, providing ample opportunities for various connections - depending on the available space near the connection. If empty spaces can be secured at a certain radius, additional pieces can be used to hold the liftarms against the trailers. Or just having a long half-width liftarm and attaching the trailers via 1.5 length pins blocked by bar pieces could provide a connection with enough strength that does not even exceed the envelop of the trailer.
Answers.UserDisplayName: zovits
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Answers.UserDisplayName: zovits
Answers.Body: <p>An option for a longer axle that allows the axle to rotate but prevents lateral movement would be to use a <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=3737b#T=C" rel="nofollow noreferrer">Technic, Axle 10L Threaded</a> with <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=4698#T=C&amp;C=9" rel="nofollow noreferrer">Technic, Axle Nut</a>s as stoppers. Single axle nuts should work but for added resilience doubling-up the axle nuts should prevent them slipping on the axle as they rotate.</p>
  <p><img src="https://img.bricklink.com/ItemImage/PN/11/3737b.png" alt="Technic, Axle 10L Threaded" /></p>
  <p><img src="https://img.bricklink.com/ItemImage/PN/9/4698.png" alt="Technic, Axle Nut" /></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-08-02T14:27:04.617Z
Answers.Text: Wow, those are quite the exotic and antique parts! Thanks for mentioning them, otherwise I'd never known they existed - even if just until 1990.
Answers.UserDisplayName: zovits
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Answers.Text: Do you know how they were used in the models?
Answers.UserDisplayName: A.L
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Answers.CreationDate: 2024-08-19T14:19:50.513Z
Answers.Text: @A.L They were all used in rotating joints to stop the sections from separating. In the backhoe ([instructions](https://manuall.co.uk/lego-set-8862-technic-backhoe-grader/), see step 18), it was to hold the backhoe securely onto the main body and to rotate it. It was similar on the power crane ([instructions](https://manuall.co.uk/lego-set-8854-technic-power-crane/), steps 12-16), holding the crane onto the wheeled body; and on excavator ([instructions](https://manuall.co.uk/lego-set-8851-technic-excavator/), step 13), holding the rotating cab onto the tracks.
Answers.UserDisplayName: MT0
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Answers.UserDisplayName: MT0
Answers.Body: <p>I have done something similar myself a few years ago.</p>
  <p>I used part
  <a href="https://i.sstatic.net/0k2xgHAC.png" rel="noreferrer"><img src="https://i.sstatic.net/0k2xgHAC.png" alt="55013" /></a>, axle with stop at one end. And ran that through a regular Technic brick with holes on each end of the connection. Then secured the other end with a stack of multiple half bushes <a href="https://i.sstatic.net/V0ZLWcut.png" rel="noreferrer"><img src="https://i.sstatic.net/V0ZLWcut.png" alt="enter image description here" /></a>. Putting multiple half-bushes against each other greatly increases the over-all friction when you attempt the pull the axle out of the set of bushes.</p>
  <p>The half-bushes have far more clutch power than the 1L sized ones and the axle comes in various lengths up to 8L (if I recall correctly) so you can go up to 12 bushes (assuming 2L needed for the bricks that provide the mounting holes for the axle ) to add more friction.<br />
  This will give you way more holding strength than any stud-based connection would supply. And will probably be close (or better) to what the turn-table could do.</p>
  <p>I would actually recommend to put at least 1 half-bush against the stop. I found that the flange on the stop is fairly small and weak and will deform when there is enough pull on the axle. A half bush as buffer fixes that problem.</p>
  <p>These bushes come in variants with 4 internal ridges (as shown in the picture) and with 2 ridges. The 2 ridge versions have less grip on the axle and would be useless for this application.<br />
  And it seemed to me the yellow ones had slightly better grip than the grey ones. That might just be coincidence though, caused by minute differences in tolerances in the pieces.</p>
  <p>A 5L axle with stop and 6 half-bushes (1 against the stop and 5 on the other end) is probably already strong enough to do what you want. And, as I said, 8L is avaialble.</p>
  <p>If you have enough space horizontally you could even use a longer regular axle (16L or even longer) and simply use more half-bushes on each side.</p>
  
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Answers.UserDisplayName: Tonny
Body: <p>I am looking for a &quot;compact&quot; (see my initial ideas for the approximate dimension I am aiming for) connection that can rotate around its axis (along the direction of connection) and that can bear a certain amount of pull forces.</p>
  <p>I want to use it for some somewhat rigid trailer connection that can pull and push <em>multiple</em> trailers (think &quot;Model Team scale&quot; in terms of size and mass) up a slope with uneven terrain.</p>
  <p>Some initial ideas:</p>
  <ul>
  <li>A regular 2x2 turntable plate, turned up sideways. As the grip is entirely provided by four studs, at least twice (in front of and behind the turntable), not to mention the small inner turntable pin, I think this will come off too easily.</li>
  <li>With a technic pin: E.g. a 1x2 brick with a pin connected to a regular 1x2 Technic brick with a hole. Two of these connectors were used to attach the modules of <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?S=6973-1#T=S&amp;O=%7B%22iconly%22:0%7D" rel="nofollow noreferrer">6973 Deep Freeze Defender</a>, and they came close to the limit of what the connection could bear there, so this is probably too weak for my use case.</li>
  <li>The <a href="https://rebrickable.com/parts/88738/technic-turntable-large-type-4-top-60-tooth/" rel="nofollow noreferrer">large Technic turntable</a> is too large for my designs.</li>
  <li>The <a href="https://rebrickable.com/parts/99010/technic-turntable-small-base-28-tooth/" rel="nofollow noreferrer">small Technic turntable</a> might fit and appears to allow for getting attached sturdily on both sides. Still, I do not have access to this part in real life and thus do not know whether the turntable halves would support any pull forces.</li>
  <li>Just an axle in the direction of the connection - any such solution seems to rely on the grip of whatever prevents the axle from slipping out, which might not be sufficient.</li>
  </ul>
  <p>Are there any tried and tested techniques for this building problem?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-08-02T09:13:36.663Z
Comments.Text: I would think the technic turntable is especially designed for the purpose you have in mind, i.e. being able to rotate while push or pull forces are applied. They are relatively cheap on bricklink.
Comments.UserDisplayName: Michael Verschaeve
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-08-02T10:33:02.873Z
Comments.Text: The small Technic turntable is practically impossible to pull apart once snapped together. It can definitely handle forces that would break other connections first.
Comments.UserDisplayName: zovits
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2024-08-04T22:49:13.877Z
Comments.Text: I can't answer, but may I suggest a name? A "compact rotatable connection that supports pull forces" sounds to me like [a _swivel_](https://en.m.wiktionary.org/wiki/swivel).
Comments.UserDisplayName: Solomon Slow
Tags: <technic><building><piece-usage>
Title: Compact rotatable connection that supports pull forces?
UserDisplayName: O. R. Mapper
ThreadText: # Compact rotatable connection that supports pull forces?
  
  (Asked by: username_0 on 2024-08-02)
  
  I am looking for a "compact" (see my initial ideas for the approximate dimension I am aiming for) connection that can rotate around its axis (along the direction of connection) and that can bear a certain amount of pull forces.
  
  I want to use it for some somewhat rigid trailer connection that can pull and push *multiple* trailers (think "Model Team scale" in terms of size and mass) up a slope with uneven terrain.
  
  Some initial ideas:
  
  * A regular 2x2 turntable plate, turned up sideways. As the grip is entirely provided by four studs, at least twice (in front of and behind the turntable), not to mention the small inner turntable pin, I think this will come off too easily.
  * With a technic pin: E.g. a 1x2 brick with a pin connected to a regular 1x2 Technic brick with a hole. Two of these connectors were used to attach the modules of [6973 Deep Freeze Defender](https://www.bricklink.com/v2/catalog/catalogitem.page?S=6973-1#T=S&O=%7B%22iconly%22:0%7D), and they came close to the limit of what the connection could bear there, so this is probably too weak for my use case.
  * The [large Technic turntable](https://rebrickable.com/parts/88738/technic-turntable-large-type-4-top-60-tooth/) is too large for my designs.
  * The [small Technic turntable](https://rebrickable.com/parts/99010/technic-turntable-small-base-28-tooth/) might fit and appears to allow for getting attached sturdily on both sides. Still, I do not have access to this part in real life and thus do not know whether the turntable halves would support any pull forces.
  * Just an axle in the direction of the connection - any such solution seems to rely on the grip of whatever prevents the axle from slipping out, which might not be sufficient.
  
  Are there any tried and tested techniques for this building problem?
  
  **Tags:** technic, building, piece-usage
  > **Comments:**
  > **username_1**: I would think the technic turntable is especially designed for the purpose you have in mind, i.e. being able to rotate while push or pull forces are applied. They are relatively cheap on bricklink.  
  > **username_2**: The small Technic turntable is practically impossible to pull apart once snapped together. It can definitely handle forces that would break other connections first.  
  > **username_3**: I can't answer, but may I suggest a name? A "compact rotatable connection that supports pull forces" sounds to me like [a _swivel_](https://en.m.wiktionary.org/wiki/swivel).  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_2 on 2024-08-02. Score: 5
  
  I would try a [3L low-friction Technic pin](https://www.bricklink.com/v2/catalog/catalogitem.page?P=32556#T=S&O=%7B%22iconly%22:0%7D), whose middle section is threaded through the pin holes of two [half-width liftarms](https://www.bricklink.com/v2/catalog/catalogitem.page?P=6632#T=S&O=%7B%22iconly%22:0%7D) (these would be joined to the trailers), and the ends capped with 1L "liftarms" (aka. [Technic cylinders or spacers](https://www.bricklink.com/v2/catalog/catalogitem.page?P=18654)) and plugging some bars (e.g. [a lipstick](https://www.bricklink.com/v2/catalog/catalogitem.page?P=93094pb03#T=S&O=%7B%22iconly%22:0%7D)) in the end holes to prevent the spacers from sliding off.
  
  A shorter option would be to fix a [3/4 Technic pin](https://www.bricklink.com/v2/catalog/catalogitem.page?P=32002) in a [half-width liftarm](https://www.bricklink.com/v2/catalog/catalogitem.page?P=6632#T=S&O=%7B%22iconly%22:0%7D) on the shorter end, attaching another one (or two) on the other end and locking both sides with any suitable 3.18 mm bar - maybe with a single piece across the whole pin.
  
  > **Comments:**
  > **username_4**: Interesting. Your solution takes lengthwise slightly less space (using a 5L axle on my variant) as mine, but the width is a minimum of 3L and mine would fit in 2L (provided the mounting to the vehicle can be done in the vertical plane). A 2L narrow bar would also work instead of a lipstick piece (lipsticks are not very common pieces in my experience.)  
  > **username_5**: This could be a good way of creating the rotation joint, but the half-width liftarms does not provide any secure way of attaching to the trailers. The half-width axle holes would likely provide too little grip. Is there another piece that could be used instead?  
  > **username_2**: @sondre99v The half-width liftarms could be quite long and could extend in different directions, providing ample opportunities for various connections - depending on the available space near the connection. If empty spaces can be secured at a certain radius, additional pieces can be used to hold the liftarms against the trailers. Or just having a long half-width liftarm and attaching the trailers via 1.5 length pins blocked by bar pieces could provide a connection with enough strength that does not even exceed the envelop of the trailer.  
  
  ---
  
  ### Answer by username_6 on 2024-08-02. Score: 5
  
  An option for a longer axle that allows the axle to rotate but prevents lateral movement would be to use a [Technic, Axle 10L Threaded](https://www.bricklink.com/v2/catalog/catalogitem.page?P=3737b#T=C) with [Technic, Axle Nut](https://www.bricklink.com/v2/catalog/catalogitem.page?P=4698#T=C&C=9)s as stoppers. Single axle nuts should work but for added resilience doubling-up the axle nuts should prevent them slipping on the axle as they rotate.
  
  ![Technic, Axle 10L Threaded](https://img.bricklink.com/ItemImage/PN/11/3737b.png)
  
  ![Technic, Axle Nut](https://img.bricklink.com/ItemImage/PN/9/4698.png)
  
  > **Comments:**
  > **username_2**: Wow, those are quite the exotic and antique parts! Thanks for mentioning them, otherwise I'd never known they existed - even if just until 1990.  
  > **username_7**: Do you know how they were used in the models?  
  > **username_6**: @A.L They were all used in rotating joints to stop the sections from separating. In the backhoe ([instructions](https://manuall.co.uk/lego-set-8862-technic-backhoe-grader/), see step 18), it was to hold the backhoe securely onto the main body and to rotate it. It was similar on the power crane ([instructions](https://manuall.co.uk/lego-set-8854-technic-power-crane/), steps 12-16), holding the crane onto the wheeled body; and on excavator ([instructions](https://manuall.co.uk/lego-set-8851-technic-excavator/), step 13), holding the rotating cab onto the tracks.  
  
  ---
  
  ### Answer by username_4 on 2024-08-02. Score: 5
  
  I have done something similar myself a few years ago.
  
  I used part
  [![55013](https://i.sstatic.net/0k2xgHAC.png)](https://i.sstatic.net/0k2xgHAC.png), axle with stop at one end. And ran that through a regular Technic brick with holes on each end of the connection. Then secured the other end with a stack of multiple half bushes [![enter image description here](https://i.sstatic.net/V0ZLWcut.png)](https://i.sstatic.net/V0ZLWcut.png). Putting multiple half-bushes against each other greatly increases the over-all friction when you attempt the pull the axle out of the set of bushes.
  
  The half-bushes have far more clutch power than the 1L sized ones and the axle comes in various lengths up to 8L (if I recall correctly) so you can go up to 12 bushes (assuming 2L needed for the bricks that provide the mounting holes for the axle ) to add more friction.  
  This will give you way more holding strength than any stud-based connection would supply. And will probably be close (or better) to what the turn-table could do.
  
  I would actually recommend to put at least 1 half-bush against the stop. I found that the flange on the stop is fairly small and weak and will deform when there is enough pull on the axle. A half bush as buffer fixes that problem.
  
  These bushes come in variants with 4 internal ridges (as shown in the picture) and with 2 ridges. The 2 ridge versions have less grip on the axle and would be useless for this application.  
  And it seemed to me the yellow ones had slightly better grip than the grey ones. That might just be coincidence though, caused by minute differences in tolerances in the pieces.
  
  A 5L axle with stop and 6 half-bushes (1 against the stop and 5 on the other end) is probably already strong enough to do what you want. And, as I said, 8L is avaialble.
  
  If you have enough space horizontally you could even use a longer regular axle (16L or even longer) and simply use more half-bushes on each side.
  
  
  ---
  
  