Home > Ideas > Compact pendular steered suspension

Compact pendular steered suspension

December 28th, 2008 Leave a comment Go to comments

Simple steered and driven pendular suspension. Very compact and strong, needs no rare parts. Step-by-step instruction provided.

One of my most popular and useful ideas. It’s a simple driven and steered pendular suspension, built without use of any rare parts like universal joints etc. It requires mainly liftarms and bevel gears. The full parts list can be seen here. The entire module’s dimensions are 15x8x5 studs plus wheels. The weight is 82 grams, and it has been successfully tested under 2 kilograms of load. All the moving parts are enclosed in liftarm frame. You can find a complete step-by-step instruction on the photos below.


dscn4596.jpg dscn4598.jpg dscn4599.jpg hwsuspension1.jpg hwsuspension2.jpg hwsuspension3.jpg hwsuspension4.jpg hwsuspension5.jpg hwsuspension6.jpg instruction01.jpg instruction02.jpg instruction03.jpg instruction04.jpg instruction05.jpg instruction06.jpg instruction07.jpg instruction08.jpg instruction09.jpg instruction10.jpg instruction11.jpg instruction12.jpg instruction13.jpg instruction14.jpg instruction15.jpg instruction16.jpg instruction17.jpg instruction18.jpg instruction19.jpg instruction20.jpg instruction21.jpg instruction22.jpg instruction23.jpg instruction24.jpg

Media reference:

nxtasy.org, TechnicBRICKs

Categories: Ideas Tags: ,
  1. liamisamonster
    May 21st, 2012 at 18:36 | #1

    maybe your thinking of the newer, 3 stud wide ones, this is thinner, yet it is 4 studs long

  2. Sariel
    April 21st, 2012 at 09:57 | #2

    No, they don’t.

  3. Fin
    April 21st, 2012 at 07:58 | #3

    Dont the teeth on th diff rub the casing

  4. Sariel
    November 8th, 2011 at 22:12 | #4

    @Jon Håvard
    This design comes from before the 3-studs wide differential. I suggest to check my newer ideas.

  5. Jon Håvard
    November 8th, 2011 at 21:45 | #5

    Could you make one with the 3-studs diff? Guess you have other plans… 😛 no offence

  6. Sariel
    August 3rd, 2011 at 14:42 | #6

    No, I lost this file somewhere.

  7. freakybuilders
    August 3rd, 2011 at 12:39 | #7

    Could you please send me the LDraw File to freakybuilders@web.de?

  8. Salih
    February 7th, 2011 at 12:27 | #8


  9. Sariel
    February 7th, 2011 at 12:23 | #9

    You can build one from the Lego 8880 set.

  10. Salih
    February 7th, 2011 at 12:08 | #10

    Can you post instructions for steered, independent suspension with drive or tell me a website where i can find one please?

  11. Sariel
    December 18th, 2010 at 14:16 | #11

    You should add shock absorbers for stability. There are plenty of ways to do so.

  12. Alexr
    December 18th, 2010 at 13:49 | #12

    so you what you are saying is that you don’t need springs.
    but wont it just tip over?

  13. Sariel
    November 5th, 2010 at 18:26 | #13


  14. Bartek
    November 5th, 2010 at 18:23 | #14

    Szkoda, jestem Twoim fanem i często wzoruje się na Twoich projektach 😀
    Miałeś może kiedyś problem z silnikiem PF XL taki iż kabelki nie łączyły??

  15. Sariel
    November 5th, 2010 at 15:34 | #15

    1. Bo 90% odwiedzających to osoby spoza Polski. A po polsku moje konstrukcje opisuję na Lugpolu.
    2. Nie.

  16. Bartek
    November 5th, 2010 at 15:24 | #16

    Witaj, dlaczego tu jest wszystko po angielsku skoro to jest polska strona??
    Chciałem się spytać czy robisz instrukcje do swoich projektów ????

  17. Sariel
    October 2nd, 2010 at 08:57 | #17

    No, I don’t, sorry.

  18. Dan
    October 2nd, 2010 at 03:17 | #18

    Hey Sariel, would you still have the ldraw file from this, do you still have it kicking around, I’m working on changing the way it is driven and it takes way too long by physical bricks. So maybe you could send me the file? Anyways great job on this system, I’m going to be using it for my physics project involving the purpose of differential gears, it was the best one I’ve found.

  19. guillem
    September 7th, 2010 at 15:13 | #19

    Hi I have 14 years
    thank you very much, it works very well and Land Rover this Tanvi done.
    guillem greetings from spain

  20. Sariel
  21. puredeath
    August 19th, 2010 at 16:05 | #21

    is there a way to make a even numbered wide steering or an even numbered wide gearbox [transmision] and there is another way to make a version of this with less parts or larger and im working on trying to build a car with my mindstorm nxt useing the 3 mindstorm motors, the “brain”, and the mindstorm ir transmiter and receiver. My remote does not have speed control and ur return 2center disign is not strong enough to move the moters onec the get withen 5 degress or so of center, and i dont have the parts to build and grear box greater than 4 speeds and i have a working version of ur 4 speed manual gear box. I have to have 2 motors suplling the powers to the wheels because the nxt “brain” is so heavy that it strains all the chasies i have made with transmisions and some of my first direct drive cars do u have and ideas i could build and i have 1 differintral no shocks
    e-mail me at: Narutokiba11@yahoo.com
    and if anyone has any ideas u can e-mail me 2

  22. Sariel
    June 20th, 2010 at 16:44 | #22

    Yes, exactly.

  23. Krika99
    June 20th, 2010 at 16:24 | #23

    Hey, how does the 16 tooth gear with clutch act as a pinion? since it does not have a cross-axle hole in it, is it turned by yet another gear from above?

  24. May 18th, 2010 at 00:21 | #24

    I continue to be awe struck by the quality coming from this website. If we, in the LEGO community had the ability I would see that once a year we would vote, worldwide, on the best, in a number of categories, and present them, not only with the international recognition they so richly deserve, and a nice trophy, and we would ask LEGO to donate some LEGO parts that the winners want so ban that they drool when they simply think about them. I am just sick and sadden, here in a nursing home and no money, when I come here, first thing, and see all of the new creations. Believe it, or not, but I see things here that ARE NOT SOLD IN THE USA.
    Now, I first want to award Paul with the top recognition for keeping this website growing, and looking so professional. When I place this site beside websites that are for corporations with millions to spend, their sites “suck”, some of my 6th grade students have done better.
    Next, I wish to congratulate Paul for the development in his design work…it comes out with each and every model that he has created. For 25+ years I was known as the “LEGO Maniac” which came from LEGO-USA for developing my schools and using LEGO as the manipulative elements for developing concepts they could carry throughout life, and serve them well. One of my students, through our hacking access into ‘milnet’ and hacking into MIT, he became friends with Rodney Brooks (Head of AI and Robotics). Once Chris graduated from High School Rodney invited him to work his way through MIT by developing the AI and ‘brain’ for LEGO. What few people realize is that we were a full 5 years ahead of LEGO with the motorized LEGO vehicle carrying a “Smart Brick” inside. This was the first step for LEGO into the world of Robotics and it came from my school. He then went to Stanford-JPL and is now on the team that has developed the “cross-over” vehicle, seen on TV and soon to start roaming the highways across the USA. I have had, from 1983 to 19998, over 278,256 students go through my 2,878 schools in all states. When I became deathly ill I had to withdraw my Founder/Headmaster positions, and when I was in the hospital I suffered 56 strokes (I survived all of them without so much a mark that would reveal to the casual visitor, that there had been, or remains, some issues that keep me here. My mind is fresh and unharmed, if I had lost my ability to think and develop, I would fall into a depression that I would fear that I may do something to myself…which won’t happen as Hospice (for people dying with a very short period of time…I am now 6..6 years in Hospice, they kicked me out of their care…Why? I didn’t die when all of my doctors said I wouldn’t lase 6 weeks after the major operation. See, I’m a tough Irishman. While I was out sick, my mind was working over what was supposed to be facing me and I forgot everything else, including my schools. Behind my back, none of my mentors (teachers) came to visit me…I am told that people don’t want to be around the dying—they have to face their own mortality. At any rate, once I realized I was not only going to live, but become better than before, I started to check into the status of my schools. I was told that a group of my “friends” had managed to steal my schools from under me and they left me with NOTHING. I was never paid the “Founder’s Fee” that the government demands of new businesses, etc. That’s what has left me without a penny to my name, otherwise I would be hounding Paul to sell some parts that I can’t get here, or maybe find someone willing to donate and ship a few special parts. My day finds me at the CPU (MS-DOS System-Windows-ME) and/or building. PCS-Edventures (The new name the thieves is now calling my schools (they dropped the name I created as a request of a 12-year-old boy who was dying, at the time, from cancer. It was called “PCS Centers for Advanced Learning,” All students liked it because one of their own named the schools. The adults in the company thought themselves more clever, so they changed it. Now I hope that my fellow brother engineers will know the part of my background that meshes with them.
    I want to now present my recognition for 13 builders of note. I will name them later, as soon as I finish reviewing the rest of the group. I wish I could put a Red Star of Recognition for “above average” creation and innovation. One thing I have realized as I examine all of the models. I see a general influence of Peter in many of the models, as the builders first hit the site. As they remain, continue building, I notice there is less the “Peter Influence” and more “Individualized personality” starts to bring out the best. I credit much of this as proper leadership coming from Paul and I think that there are other “mentors” in the group willing to be self-less, drop what they are doing, and help the one seeking help. CONGRATULATIONS TO EVERYONE. I surf a lot these days and there is NO SITE that can compare with place that I call “home” and whose members I call my “brothers and sisters.”
    If anyone would be interested in helping me get my hands on some LEGO Technic gears, etc. send me an Email and I will reply with the small list (I promise) that I drool over. I really miss the group building sleep-overs we held frequently, especially in the summer when we were outside cooking over a fire and sleeping under the stars and talking through the night about LEGO. [mcshane.patrick9@gmail.com]

  25. Sariel
    March 15th, 2010 at 13:30 | #25

    I’m just working on one in my Tatra. If it turns out good, I’ll probably publish some instructions.

  26. gimba96
    March 15th, 2010 at 13:11 | #26

    Great work!
    I used it already a couple of times.
    Only one question: Can you make an independent version?

  27. Sariel
    February 19th, 2010 at 07:35 | #27


  28. cody
    February 19th, 2010 at 02:40 | #28

    so can this work with lego nxt
    and how does it work like do u need two motors idk

  29. Sariel
    February 16th, 2010 at 11:34 | #29

    The bevel gears usually can handle the torque from PF XLs. When using two PF XLs together, I tend to connect them directly. You’re right that there are small differences in their speeds and it’s a better solution to connect them through a differential, but a direct connection is simplier, stronger and less likely to fail under high torque.

  30. Beppe
    February 16th, 2010 at 11:27 | #30

    Some more questions regarding high torque and gears. Can the bevel gears in the differential handle the high torque from the PF XL motor?

    This question might not fit here, but I’ve seen that some of your models have drivetrains that are driven by two PF XL motors. In these cases, do you use a differential to distribute the torque from each motor to the drivetrain? Or do you simply connect them directly to the drivetrain? If the latter is true, do the motors “balance” each other well? I mean, even if the motors have the same speed on the paper it could differ in reality which could be a problem in a direct connection.


  31. Sariel
    February 15th, 2010 at 13:18 | #31

    I think bevel gears are better in general, because their teeth design is more efficient. No, the PF XL can’t break the new u-joint, unless you add some gear reduction to it.

  32. Beppe
    February 15th, 2010 at 13:15 | #32

    The topic of high torque on gears and drivetrains is an interesting one. After having read your gear tutorial I understand that the regular 24 teeth gear and the double bevel 20 teeth gear are the strongest ones. Are they equal in strength or is one of them the better one?

    Can you tell anything about the universal joint? How much torque could it withstand? Would a PF XL motor break it?

  33. Sariel
    February 12th, 2010 at 20:34 | #33


  34. Beppe
    February 12th, 2010 at 19:41 | #34
  35. Sariel
    February 11th, 2010 at 22:58 | #35

    Bevel gears are no good for large loads. Try knob wheels instead.

  36. Beppe
    February 11th, 2010 at 22:36 | #36

    I’m having problem with the bevel gears in the steering axle. They slip when the load is getting large, for example when simply trying to push a heavy object with the car. I’m not using the differential since I don’t have one. The left and right side are simply connected with an axle and the axle is driven by a PF XL motor. The gear ratio is 1:1 from motor to wheel.

    Any idea of what is causing the problem? Or are bevel gears and a PF XL motor simply a NO, NO? Can I expect to have the same problem with the bevel gears in the differential if I use one?

    Thanks for these wonderful web pages!

  37. Sariel
    January 25th, 2010 at 16:10 | #37

    This is a different suspension of the same type, the way of using shock absorbers is the same: http://www.brickshelf.com/gallery/Sariel/Cat990H/dscn7018.jpg
    Note that you don’t actually need absorbers for this suspension. They are only useful for improving stability.

  38. Ben
    January 25th, 2010 at 15:13 | #38

    Oh, OK, thanks. Do you happen to have any pictures showing it with shock absorbers placed on it?

  39. Sariel
    January 25th, 2010 at 14:44 | #39

    No. It rotates around longitudinal axle, thus allowing one wheel go up and the other go down when they meet an obstacle. Like here: http://www.brickshelf.com/gallery/Sariel/FaunSLT/dscn6202.jpg

  40. Ben
    January 25th, 2010 at 14:09 | #40

    So the whole structure goes up/down together?

  41. Sariel
    January 25th, 2010 at 13:33 | #41

    Because this is a pendular suspension, not an independent one.

  42. Ben
    January 25th, 2010 at 13:12 | #42

    I just don’t see where the ‘suspension’ comes in. There aren’t any shock absorbers or anything similar on it.

  43. legonut
    January 5th, 2010 at 04:07 | #43

    i made this using your system, but flipped the diff. around and used no wormgear to allow much more speed

  44. blarson
    January 5th, 2010 at 02:22 | #44

    thanks and they both look great

  45. Sariel
  46. blarson
    January 4th, 2010 at 22:43 | #46

    what creations have you made with this design?

  47. Sariel
    January 4th, 2010 at 19:14 | #47

    Well you don’t.

  48. blarson
    January 4th, 2010 at 18:58 | #48

    how do i make one of these with the new differential


  49. joalegofreak
    January 2nd, 2010 at 11:21 | #49

    Use the new 3 studs wide differential in it

  50. diego
    November 25th, 2009 at 20:29 | #50

    I made some changes, have you read my mail?

  51. Sariel
    November 23rd, 2009 at 17:12 | #51

    Then use a fast motor or gears to accelerate it prior to driving the suspension module.

  52. diego
    November 23rd, 2009 at 17:04 | #52

    Yes, but it makes it very slow as legobuilder said before.

  53. Sariel
    November 22nd, 2009 at 18:35 | #53

    Because it’s a very compact way to transfer the drive to the differential.

  54. diego
    November 22nd, 2009 at 18:33 | #54

    why is it necesary to use a worm gear? can I avoid using it?

  55. lego+car= :-D
    November 19th, 2009 at 17:56 | #55

    thats a good idea but because im too young, I dont have the peices or the money yet-i have to wait till christmas!

  56. MB
    October 24th, 2009 at 18:11 | #56

    OK, now I get it 🙂 what is the purpose of the clutch gear.
    And the beam 3 problem I solved adding long pins as stoppers.

  57. MB
    October 24th, 2009 at 16:07 | #57

    Couple of question:
    Is the instructions,missing a picture? 34?
    Because the cluch gear doesn’t work. It makes the steering turn with a half bush with gears(?) but it doesn’t slip like clutch is design to do…?
    And second problem is that the beam 3:s are pushing liftarms 2825 loose.

  58. legobuilder
    August 19th, 2009 at 09:16 | #58


  59. Sariel
    August 18th, 2009 at 22:47 | #59

    Perhaps try a stronger motor or reinforce the model.

  60. legobuilder
    August 18th, 2009 at 19:08 | #60

    Sariel :@legobuilderYeah, you can use a faster motor or speed up the input with some gears.

    if I speed up the input with gears the friction is so high that I lose power or my model is breaking in pieces:(

  61. Sariel
    August 17th, 2009 at 23:38 | #61

    There are dozens of possible solutions, and none of them is perfect. I’d like to know a really good one myself.

  62. legobuilder
    August 17th, 2009 at 21:59 | #62

    I want to build a big strong trtr but how can i made this trtr 4wd?

  63. Adi
    July 26th, 2009 at 11:50 | #63

    i now know how to do it.

  64. Sariel
    July 26th, 2009 at 10:43 | #64

    Then perhaps you should look for help at the Bricklink.

  65. Adi
    July 26th, 2009 at 10:05 | #65

    i really want to make this but i dont have a differential. i want to buy one from bricklink but i dont know how to do it.

  66. legobuilder
    June 29th, 2009 at 18:47 | #66

    ok I’ll try it:p

  67. Sariel
    June 29th, 2009 at 17:40 | #67

    Yeah, you can use a faster motor or speed up the input with some gears.

  68. legobuilder
    June 29th, 2009 at 17:34 | #68

    nice idea but it’s very slow any suggestions how I can made it faster? greetings legobuilder

  69. OlSom
    February 27th, 2009 at 19:18 | #69

    Thx a lot dude 😉

  70. February 6th, 2009 at 17:35 | #70

    This axle was very inspiered. But in my case not compact enought.

  1. January 9th, 2012 at 17:09 | #1