Tilting Trikes Part 1 - Velomobile and Motorcycle Trike Tilting Mechanism Design

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  • Опубліковано 25 чер 2024
  • This video looks at the design considerations for the tilting mechanism for a three-wheeled velomobile, trike or motorcycle. It covers the geometry of various configurations and how to avoid pitfalls of excessive tyre scrub and unsuitable arrangements. I have used cardboard models to illustrate the topics covered. Hopefully, this video will give you the information you need to design your own tilting mechanisms to give a nice-handling machine.
  • Наука та технологія

КОМЕНТАРІ • 382

  • @frankie8762
    @frankie8762 Рік тому +6

    Your a champion to share all these principles, all in all your card cut out concept is the best, one actually gets it

  • @davidvogl5447
    @davidvogl5447 2 роки тому +14

    Really informative for a person who wants to build a tilting recumbent. You’ve given me a far greater understanding towards this endeavour👍

  • @zapplespoon8917
    @zapplespoon8917 2 роки тому +16

    Thank you for sharing this information. I have been trying to make a working Velomobile design. It's very hard to find people willing to share their concepts.

    • @lewisbrodnax2682
      @lewisbrodnax2682 Рік тому +2

      Try to find a blueprint for the original tilting sidecar on 20s-30' s Harley- Davidson rigs. I can't recall any more if that was a Harley or tilt- car patent. But talk to your local librarian, that's what they do... Find obscure source's of data in places you and I will never think of. Good luck + I'll catch you later.

    • @CraigLandsberg-lk1ep
      @CraigLandsberg-lk1ep Місяць тому

      Have you seen the F300 Life-Jet German prototype from the late '90's? Worth a look 😅

  • @chaosofpeace5150
    @chaosofpeace5150 5 років тому +48

    Please keep making videos sir. This was very educational for my own project.

  • @Mad.Man.Marine
    @Mad.Man.Marine 4 роки тому +2

    Pretty cool. When ever I’m designing new machines. I always do cardboard and push pins. Works a treat and makes for real easy adjustments. Can’t wait to see what you build.

  • @BrianPalmerEDU
    @BrianPalmerEDU 4 роки тому +2

    Thank you so much for this talk through of so many aspects that come to play in a suspension design like this. Much appreciated!

  • @robertlyndon2892
    @robertlyndon2892 4 роки тому

    Nicely done and the cut out graphic made it crystal clear. Cheers.

  • @douglasgallardojr4759
    @douglasgallardojr4759 Рік тому +1

    This is a beautiful video. The communication works perfectly.

  • @Jacopo.
    @Jacopo. 4 роки тому +2

    Super interesting analysis, thank you for your work.

  • @maxsainty9816
    @maxsainty9816 4 роки тому +7

    I found this video to very interesting as I'm considering building my own velomobile

  • @MrSaemichlaus
    @MrSaemichlaus 3 роки тому +2

    Man this video is fantastic!! I'm working on something similar and this is a gold mine!

  • @hafeexius
    @hafeexius 4 роки тому +2

    Thank you for the educational video. Much appreciated!

  • @fonwoolridge
    @fonwoolridge 3 роки тому +2

    Very interesting.... I will be back again for more inspiration on my project! Bravo!

  • @chrissmith7669
    @chrissmith7669 8 місяців тому +1

    Very interesting. I was looking at how to make an IRS trick tilt and this gave me food for thought

  • @sandiandlee
    @sandiandlee 3 роки тому +5

    That was excellent, Bravo!!! I build gravity racing vehicles and I have always thought a tilting suspension would be amazing, thank you for sharing such a vast amount of time and work!

  • @cliffordharley4322
    @cliffordharley4322 4 роки тому +2

    Very interesting! Tilting seems to be the future of trike design!

    • @randominternetguy
      @randominternetguy 4 роки тому

      It is, but even pros don't have the solution... maybe sk18 whatever with his wierd ass channel name and sick af asl.

  • @greenarmy4705
    @greenarmy4705 4 роки тому

    That's good illustration bro!

  • @skraman69
    @skraman69 Рік тому +1

    Superb and systematic approach to arrive various solutions for tilting wheels

  • @amardeepberad3586
    @amardeepberad3586 4 роки тому +1

    Great Explanation Technique...

  • @necdetsaltek6790
    @necdetsaltek6790 2 роки тому +1

    That was excellent, Bravo!!! I

  • @demonxelloss
    @demonxelloss 4 роки тому

    A very helpful video for my tilting trike construction ;)

  • @eskanderx1027
    @eskanderx1027 Рік тому

    Great stuff!
    Thank you mate!

  • @user-lt7cs4tg5b
    @user-lt7cs4tg5b 4 роки тому

    이제까지본 강연중에 최고입니다.이해하는데 많은도움이되었네요. 만들떼 참고할게요

  • @joelrebelo7292
    @joelrebelo7292 2 роки тому +1

    beautiful explaination and amazing idea of testing different ideas. this is how i would do it.

  • @Witsenburg
    @Witsenburg 5 місяців тому +1

    Hi, I'm doing a similar exercise so thanks for posting this. What I am looking into is different tilt on the wheels, less on the outside of the turn and more on the inside, making the imaginary lines through the wheel axles meet in the centre of the turn.

  • @IvanQuaglia
    @IvanQuaglia Рік тому +1

    For ages I been "planning" to make a EV trike 1+1 in tandem with motorcycle parts, but, since i didnt have the time space or money im seriulsy thinkin a electrically assisted trike bike to start with, this exercise was really very informative. thanks

  • @richarddavies7728
    @richarddavies7728 Рік тому +1

    Excellent thank you for this.

  • @2pi628
    @2pi628 3 роки тому +2

    Best Explanation video on UA-cam!!
    Thanks!

  • @irsyansani6866
    @irsyansani6866 4 роки тому +1

    nice information sir. thankyou so much. its can help me to finish my final project. please keep this video sir :)

  • @Ale_775
    @Ale_775 6 місяців тому +1

    Amazing!

  • @philcmoa6080
    @philcmoa6080 4 роки тому

    Very good job, Thank you this video, Good luck ...

  • @kodicogburn935
    @kodicogburn935 3 роки тому +1

    This was very helpful. I did find success with slight separation with of the arms from the center point and using the t model but the t shape is just about 1/3rd the height of the space between the upper and lower arms. The points where the shocks connect to the t is the same as the inner pivot points of the arm. Then using the distance for the shock to measure out where it would attach to the lower arm. For body wise you may have to make a slight deviation in the body to allow room for the shocks which aerodynamically shouldn’t effect it to much. You can also prevent a lot of aerodynamic loss by using fine bristles on the slits which will allow it to essentially close the slit.

  • @AuroraCypher
    @AuroraCypher 3 роки тому +3

    This is by far the most details built of the Tilting Trike ! I know im like 2 years late to this video but instant sub and love your build series

  • @Serenelove520
    @Serenelove520 4 роки тому

    You sir, are a genius

  • @serkanatila3141
    @serkanatila3141 Місяць тому +1

    Kral , çok güzel olmuş eline sağlık

  • @mehmetcanaz2152
    @mehmetcanaz2152 4 роки тому

    good job bro,please keep create like these videos

  • @activedrive8310
    @activedrive8310 4 роки тому

    Thanks! I thought about it, but did not think to make simple models!)

  • @realnutteruk1
    @realnutteruk1 4 роки тому

    Fantastic piece of analysis! I've done most of this thinking before but without the pretty cardboard aided design. I don't have an aversion to FWD, so the image you showed of the tilting delta trike was right up my street.

    • @MetalMachineShop
      @MetalMachineShop  4 роки тому

      I am moving from cardboard to computer aided design for the next phase!

    • @daszieher
      @daszieher 4 роки тому

      The velotilt project was for sale not too long ago. It has plugs and molds for the body and some design work

  • @user-eb5oq8lt2s
    @user-eb5oq8lt2s День тому

    Thank you very much !

  • @DrXupetin
    @DrXupetin 8 місяців тому +1

    Excelente trabajo. Estoy definiendo como hacer el basculante de mi futuro triciclo invertido. Gracias !!!

  • @veridical22
    @veridical22 3 роки тому

    The minds and technology of Lithuanian engineering are rough diamonds.

  • @projectastra8350
    @projectastra8350 3 роки тому +4

    Thank you for all your efforts, I have been thinking of building an electric trike and have been stumped for a long time on this issue.

  • @lewisbrodnax2682
    @lewisbrodnax2682 Рік тому +1

    Few people today recall that the first Harley- Davidson side hacks we re of a tilting design. H- D didn't make them, that was a contract with a private co. During WW 11, the company made bus replacement parts. Afterwards that company was still in business, Nowadays they make the tilting platform buses in Los Angeles California.

  • @hershkoyi
    @hershkoyi 4 роки тому

    Super design super technic 👌👍🌹

  • @guillaumevincent716
    @guillaumevincent716 Місяць тому +1

    VERY IMPRESSIVE

  • @edsondonascimento3412
    @edsondonascimento3412 3 роки тому +1

    Seus vídeos são ótimos, projetos completamente viáveis ,mesmo para quem não é um profissional na área, seria possível realizar com suas dicas .

  • @johnwhauserman
    @johnwhauserman 3 роки тому +1

    Thank You, Thank You, Thank You.

  • @quebuenavaina
    @quebuenavaina 2 роки тому +1

    Wow excellent video

  • @user-jh9dk9te4i
    @user-jh9dk9te4i 7 місяців тому

    你讲的很细致,谢谢 你

  • @BabylonPatrol
    @BabylonPatrol Місяць тому +1

    great!

  • @osmanharmankaya9777
    @osmanharmankaya9777 5 років тому

    Motosiklet Trike Devirme Mekanizması Tasarımı bilgilendirme için teşekkürler

  • @MrLemaner
    @MrLemaner 4 роки тому

    very nice and cleaver! thanx!

  • @archdentadit8893
    @archdentadit8893 4 роки тому +1

    Hi ... Thanks for this video, i'd love, i'm the new followers.😊

  • @johnmoncrieff3034
    @johnmoncrieff3034 4 роки тому +1

    This is a very interesting video with a range of possible designs. The only thing I would say is you are having the single wheel on the same plane as the other two. As the single wheel is at least three/ four feet behind or in front of the other two the amount of scrub or lift can be ignored due to this change in the plane!

  • @irfantanjung2924
    @irfantanjung2924 3 роки тому +1

    Good job bossqua 👍👍👍👍👍

  • @spike7269
    @spike7269 5 років тому

    thanks i am converting an e-bike to tilt trike this will help

  • @blackarmored
    @blackarmored 4 роки тому

    tnx for the load of info , I would try to take the whole or at least most of the mechanism in front or rear of the body that should be possible with 2 foil shaped carbon arms . that would take the wheels completely to the front or rear of the vm . if you make the same on the other side you can suspend the drivers pod in between them with a lot of space inside . the hub-less wheel idea of nelson would complement it nicely :)

  • @hermandurieux3247
    @hermandurieux3247 4 роки тому +3

    Great Presentation, I’m working on an idea for a tilting trike recumbent myself. Challenging I must say, your approach is inspiring!

  • @creativecityis
    @creativecityis 4 роки тому

    in my tilting trike design i decided that i wanted to control the lean with my arms, ok ok i havent built it yet, however in my design both wheels are individually suspended and i have a rod that allows me to drop each wheel individually. this video did point out to me how im going to run into heaps of wheel scrub. bugger, but his is prototype #8 there is always #9. thanks for this video as its dificult to find any info on how to build a tilting teck into a trike. i recon when this is solved it has the potential to compete with cars. who wouldnt want vehicles to be a third the size and heaps more power eficent probably dreaming, but hey, dreams are free :-)

  • @aikabdroqib5191
    @aikabdroqib5191 2 роки тому +1

    Thanks sir

  • @rogergarcia3021
    @rogergarcia3021 4 роки тому +1

    really like your evaluation, trail and error. where the center joints come together , please consider sliders that cross before connecting to shocks? thanks

  • @johanventer5730
    @johanventer5730 3 роки тому +1

    Great stuff now I need to learn english.😄 Greate job...

  • @Golgi-Gyges
    @Golgi-Gyges Місяць тому +1

    There's no right or wrong. It's what works best.

  • @Gallardo6669
    @Gallardo6669 4 роки тому +6

    Best way to create prototypes in smale scale is Lego technik!!!!! Thx for the great video.

    • @MetalMachineShop
      @MetalMachineShop  4 роки тому +4

      Ha! I actually did that. Ran out of bits though!

    • @daszieher
      @daszieher 4 роки тому +3

      My experience is the same. 3D CAD takes the design to a next level.
      From my purely digital work I learned that a powered or at least partially powered vehicle is necessary to achieve gains from the heavy tilting mechanism.

  • @salimkumar9748
    @salimkumar9748 4 роки тому

    Thanks

  • @gemitalico1
    @gemitalico1 2 роки тому +1

    me gusto mucho la excelente explicación y los diferentes modelos y problemas que presentan, han sido de una gran ayuda para mi, quería sugerir en cuanto a la suspensión, porque no colocas un pequeño sistema de suspensión en cada rueda, igual que la que usas en la central y que cada rueda suspenda por individual, te voy a enviar un modelo de suspensión sencillo que usa una trike bike, buscare el link del vídeo y te lo comparto en otro msj

  • @autotuningkmv
    @autotuningkmv 4 роки тому

    Большое спасибо!! Очень помог!! Взял себе на заметку!!

  • @AG-id5fj
    @AG-id5fj Рік тому +1

    Nice video

  • @roman_abelardo
    @roman_abelardo 4 роки тому

    Excelente!!

  • @Retrofordguy
    @Retrofordguy 5 років тому

    Been thinking of a motorcycle along these lines and having same issues finding a decent suspension setup without drawbacks whilst ensuring suspension and tilting work in harmony

  • @AngelAndTheWolf
    @AngelAndTheWolf 4 роки тому

    A wide track may keep your trike from tipping on corners, but a fast enough turn could break the bead on your tires. You need tilting to keep the forces in line with your axle.

  • @mikebull6
    @mikebull6 4 роки тому +2

    What a great video with so much detailed information, Just a thought, would you use any caster angle with these setups for a tadpole trike configuration.

    • @MetalMachineShop
      @MetalMachineShop  4 роки тому +4

      Mike Bull hi, thanks for your comment. The video just shows the tilting geometry, the steering geometry will require a castor angle and king pin angle to prevent bump steer. I’ve been working on these aspects of the design and am hoping to upload another video one these aspects in due course

  • @andycapo9you
    @andycapo9you 4 роки тому

    Cntes Engeneering. Have a look. Great job!

  • @thecontrarian9933
    @thecontrarian9933 4 роки тому

    You should look at tilting mechanisms for motorcycle cars. I'm not sure if it would work with independent suspension but something like the Flxi Flyer might simplify things. I think once you start to look at how much turning the wheels starts to change and complicate load and geometry you might forget about some of your concerns.

  • @mikek7153
    @mikek7153 4 роки тому

    Thank you MMC, very very interesting, you saved me a lot of work. One mechanism you didn't try was two pivot points in the center on the lower arms and one on the top, the same they use on the Quadro, do post another video if you try this geometry please. Thanks again for going to all this trouble.

    • @MetalMachineShop
      @MetalMachineShop  4 роки тому

      Thanks! I think the Quadro design as you describe it would make the wheels angle outwards slightly relative to each other as the machine tilts or suspension compresses. The effect would be greater the further apart the bottom pivots are. I’m not sure what the advantage of this would be, but the Quadro seems to work pretty well!

    • @mikek7153
      @mikek7153 4 роки тому

      MMS, I solved the above problem I discussed in my previous post (Quadro) simply by using your number 4b and turning it upside down, it would have the same result, I'm just wondering how Quadro solved this or didn't they ???? Correct me if I'm wrong but to have the correct geometry the top and bottom pivot points would have to have be aligned in the center such as in
      figure 2a.

    • @mikek7153
      @mikek7153 4 роки тому

      Do let us know how you solved the steering, for your project. I would imagine it would be direct steering as in a push bike but with scooters and motorbikes the preferred method seams to be a tie rod arrangement, I'm exploring some sort of direct method of steering for motorbikes to keep the whole thing as light as possible.

  • @osalbuos
    @osalbuos Рік тому +1

    Muchas gracias por todas sus explicaciones. Me encanta este diseño, pero en suramérica son muy poco empleados y las rutas para bicicletas no son muy seguras.

  • @pep2tize
    @pep2tize 4 місяці тому +1

    very interesting, perhaps you could use the buddy it self (a shell like) to transfer horizontal forces across. Could not see very clear the relationship to the driver's geometry.

  • @truthseek1790
    @truthseek1790 5 років тому +3

    @Metal Machine Shop This appears to be the most comprehensive coverage on the subject on this platform. Congrats for that. No doubt many hope that this project comes to fruition and viewers get more information helpful to constructing the proposed vehicle. It is very curious that little is now heard of the much praised "Velotilt" trike with two rear wheels, first heard of about 2012. It looked so promising, while it's apparent absence from the market place suggests that it is still overcoming problems. Any light you could shed on this matter would be much appreciated. I look forward keenly to follow ups on this project. I am surprised that the topic of a leaning velo is not far more popular.

    • @MetalMachineShop
      @MetalMachineShop  5 років тому +1

      Thanks for the comment! I'm not sure what happenend to the Velotilt, I haven't found any up-to-date news on the internet. Nice looking machine though. It uses a different sort of tilting mechanism that I didn't cover in my video.

    • @truthseek1790
      @truthseek1790 5 років тому

      @@MetalMachineShop Remain keen to know if this velomobile is being built and hope you will advise along the way. Thanks for the velomobile upload.

    • @MetalMachineShop
      @MetalMachineShop  5 років тому

      I'm still working on the design so I'm not sure whether I will ever build it. Once the design is finished maybe I will share it with the velomobile community to see whether it's good enough to build! I'll try to upload another video in due course.

  • @drmosfet
    @drmosfet 4 роки тому

    Thanks good information to consider, Utility EV could greatly benefit from tilting technology, only problem is the outrigger wheels used often exceed the form factor of a motorbike.

  • @AttemptMade
    @AttemptMade 4 роки тому

    I was actually thinking about a similar velomobile design, but for mine the body would be slightly higher and flatter on the bottom, and the fairing would be T shaped looking roulghly like cannards but capable of flexing. I was wanting to do a jet plane canopy like teardrop shaped glass dome on the top as well. I would love to work with you on the design and implementation.

  • @thechumpsbeendumped.7797
    @thechumpsbeendumped.7797 4 роки тому +16

    Very interesting, I’d love to see follow up vids on this project.

    • @MetalMachineShop
      @MetalMachineShop  4 роки тому +5

      More planned...!

    • @thechumpsbeendumped.7797
      @thechumpsbeendumped.7797 4 роки тому +1

      Excellent.

    • @ASCENDU
      @ASCENDU 4 роки тому

      Hi, you would also consider to follow up our tilting trike ASCENDU, we have a youtube channel, ua-cam.com/channels/u869xo02p4utwZpVxmCCaw.html

  • @LeesChannel
    @LeesChannel 2 роки тому +2

    When it comes to driving 2 rear wheels I think driving the rear axel with one-way clutches on either wheel would be a more elegant solution than a differential. Basically, all of the power would go into whichever wheel is moving slowest, and the vehicle would be self-righting (it would want to go straight) and it would never spin out unless BOTH wheels had no traction. Basically it would function opposite of a differential. The Quattrovelo has a system like this.
    I know you aren't intending on making a delta configuration, but I thought I might mention it since it was discussed in the video.

  • @RomanTechnician
    @RomanTechnician 4 роки тому

    I'm not sure but it seems that body clearance should increase as the tilt angle increases for vertical state stabilization. But not much, probably it causes risk of overturn at speed. Thank you for shared analysis.

  • @CrusaderSports250
    @CrusaderSports250 9 місяців тому

    Fourteen minutes very well spent, been considering this and the problems that arise for some time now, out of interest how big a problem is tyre scrub and if you mounted the lower arm where it met the tyre slightly higher and angled the wheej outwards, (positive camber), would that be of benefit,

  • @mk3brakes569
    @mk3brakes569 4 роки тому +1

    Excekent discriptions,,, regads Ricky Bolivar - Argentina

  • @cengooley6737
    @cengooley6737 3 роки тому +1

    supeeeerr wooouuwww heyt bee helal sana braawuooooo

  • @fer3.0fg67
    @fer3.0fg67 Рік тому +1

    WOW!!!!

  • @MytryKHOVANSKY
    @MytryKHOVANSKY 4 роки тому

    good

  • @sanglambo
    @sanglambo 4 роки тому

    Good

  • @thundercuntinashoefullofpiss
    @thundercuntinashoefullofpiss 4 роки тому

    hats off 2 u sir im just going into this with the general view all ideas must work but after your vid it would appear not so (SO) subs with thumbs up are an iregular occurance from me as it takes a mind blowing amount of learning in the minimal amount of time at wich the end i can actually say " I GET IT " LOL U SIR TICK ALL THOSE BOXES so i sub thee with great thumbness and i THANK YOU for your time :)

  • @GoldenSim27
    @GoldenSim27 4 роки тому

    your suspension arms pivots are offset of the wheel , then put the pivots on the body offset also . left wheel arms mounted ofset to the right on the body and right wheel pivots offset to the left on the body and they cross them self

  • @flannel2699
    @flannel2699 4 роки тому

    This is uncannily like a project I shelved a decade or so ago. Even the sketches and model are pretty much identical. Great minds..!
    Have you considered a delta layout with a Calleja type twin trailing swing arm setup. Calleja used a diff on his motorised test bed but with a narrow enough track you could possibly do without - or even drive a single rear wheel ( unless it would cause some unwanted yaw effects..?)
    Anyway it was fun to watch you talk through the same work, the same way.. Thanks for sharing.

    • @MetalMachineShop
      @MetalMachineShop  4 роки тому

      Ha! I don’t claim any of my work is original - interesting to hear that other people have come to similar conclusions! I think the tadpole configuration has advantages in terms of mechanical simplicity but the deltas probably look better.

  • @KevinNguyen-zn4vv
    @KevinNguyen-zn4vv 2 роки тому +1

    Perfect example of how to visualize physics without all the math.

  • @derekmcdaniel6029
    @derekmcdaniel6029 Рік тому +1

    I would mimic oversized skateboard trucks in my design.

  • @stevedelaire6258
    @stevedelaire6258 4 роки тому

    Some insight from having built a bunch of human powered streamliners including 3 wheeled leaners.
    Weight and complexity are always a hindrance to efficiency when powered by fractional horsepower engines (humans).
    Lighter, simpler yields the best results.
    A 2 wheeler with side openings so either a foot or hand can touch the ground at a stop worked out the best ... for me.
    The speeds that can be attained with a good light weight human powered streamliner it truly amazing.
    Your results may vary.

    • @MetalMachineShop
      @MetalMachineShop  4 роки тому

      Hi, thanks for your comment! I totally agree that light weight and simplicity is the right way to go for out and out speed. I am prepared to sacrifice a bit (but not too much) of speed for practicality. I am pitching my design at reasonably practical year round (in UK) commuting type use, and and intending to use electrical assistance. I also have in mind a faster two-wheeled design. Anyway, it’s all still on the drawing board at this point!

    • @stevedelaire6258
      @stevedelaire6258 4 роки тому

      Lightweight and simplicity is a nice advantage for all weather, everyday practicality. Even when adding the weight of motors and batteries. This statement is based on years of complex testing and personal experience.
      All the best with your build.
      Your results may vary.

  • @redramos7208
    @redramos7208 Рік тому +1

    💖💖💖

  • @AngelAndTheWolf
    @AngelAndTheWolf 4 роки тому

    I'm just thinking Ackerman should be applied to your tilting action, as that is how you'll be steering at higher speeds. I assume higher speed correct tracking is more important to you than low speed start and end of ride tracking. The turning mechanism is only needed for slow speed small radius maneuvering. Maybe the tilting mechanism can be a sub-assembly mounted on a pivot, which would be the pitch axis for turning the whole tilting assemble in the left/right horizontal plane for tight turns.I'm Thinking of a handle bar that can be pushed left and right for tilt, and twisted in the usual bicycle manner for turning the tilt mechanism on the horizontal plane for tight turns. I'm saying this several different ways, because I can't put a picture of it on UA-cam.

  • @patrickmckowen2999
    @patrickmckowen2999 4 роки тому +1

    Just wonderful. Thank you.
    Your 1st "optimal" configuration will work for my design.
    Have you started it yet?
    Cheers

  • @parstal4972
    @parstal4972 3 роки тому +2

    Thank you, really interesting. I am about to make a reversed Electric motorcycle and aim to make it to tilt.
    BR Per
    .

    • @MetalMachineShop
      @MetalMachineShop  3 роки тому

      Thank you! Good luck with your project, it would be great to see it when it's finished!

  • @danielgotz1027
    @danielgotz1027 3 роки тому +1

    A tricky bit with the spring. Perhaps a torsion bar. Like an old pickuptruck.