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BMR-2

August 15th, 2011 Leave a comment Go to comments

Model of a Spanish armoured personnel carrier. Features full independent suspension, 6×6 drive, 2-speed gearbox, remotely opener rear ramp, deployable tracked drone and lights.  

Datasheet:

Completion date: 14/08/2011
Power: electric (Power Functions)
Dimensions: length 56 studs / width 29 studs / height 24 studs
Weight: 2.306 kg
Suspension: full independent
Propulsion: 1 x PF XL geared 6.5:1 (low gear) / 2.3:1 (high gear)
Motors: 1 x PF XL, 3 x PF Medium, 2 x micromotor

BMR-2 is a modern Spanish armoured personnel carrier. It’s a fairly typical vehicle for its class and I have chosen it mainly for its short chassis with first and last axles steered. I was hoping it would work well in an outdoor Truck Trial race. Unfortunately, it turned out that this kind of a steering system won’t work for a vehicle of that size, weight and with these tires without differentials. I haven’t been able to build it on time and therefore I abandoned plans to try it in a race.

The model had a full independent suspension that used 8297’s set components. Axles #1 and #3 were steered through a common steering shaft, by a Medium motor geared down 9:1, with a safety clutch. All wheels were driven by a single PF XL motor through a remotely controlled 2-speed linear gearbox.

The chassis was entirely studless, with majority of internal components located above the middle axle. The body consisted mainly of plates supported by a frame of Technic bricks. This solution resulted  in an unusually low weight – something I was expecting and which prompted me to try using only one shock absorber per wheel. The suspension created this was was very soft, and even though it worked, the model displayed apparent tendency to ‘sit down’ on the third axle.

Close to the end of the building process I have realized that I can save up some internal space at the back of the model. It led me to realize an idea that followed me for a while (or was it planted?) – a small tracked drone deployed from inside. In a way, this was a MOC within a MOC, and thus: a MOCception 🙂 The drone was extremely simple, built around two micromotors with chains instead tracks. The micromotors were powered and controlled by two long wires connected to a separate IR receiver inside the transporter.  The drone could be deployed once the rear ramp was opened and it could operate outside its carrier. It worked well, but due to its extremely low weight it was somewhat struggling against the wires. I have also integrated something like a simple passenger compartment into the upper hull’s surface, and it turned out to be perfectly fit for a single dwarf hamster.

Photos:

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Video:

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  1. Vadim
    November 16th, 2014 at 16:55 | #1

    Thank you!!!Good luck!!!

  2. Sariel
    November 16th, 2014 at 16:41 | #2

    @Vadim
    At Bricklink. This link is my every single video.

  3. Vadim
    November 16th, 2014 at 16:24 | #3

    Hi !!!Where did you buy parts for tanks??Throw link,please!

  4. Sariel
    January 31st, 2014 at 09:32 | #4

    @Antony
    No, I’m afraid not. And XL motor is bad for steering.

  5. Antony
    January 30th, 2014 at 22:30 | #5

    any place where i can find the tutorial to the steering system WITHOUT having to buy your book? you see, i can not pay in credit card. im 15 >.>
    anyway, will the steering work with a small or xl motor? i dont have a medium.

  6. Sariel
    April 1st, 2013 at 10:25 | #6

    @nitwity
    It’s a simple suspension, you can see it in my book.

  7. nitwity
    April 1st, 2013 at 05:30 | #7

    Do you remember at least how to make the wheels drive and turn all at once, this is where I am lost *the back and front wheels can turn while driving*@Sariel

  8. Sariel
    March 29th, 2013 at 09:52 | #8

    @nitwity
    Sorry, but no, it’s not possible.

  9. nitwity
    March 29th, 2013 at 02:14 | #9

    I hate to ask but can you either post building instructions for ONLY the chassis or at least a picture of the underneath and ontop of the chassis, Im trying to model this, I seriously want 1

  10. Sariel
    January 28th, 2013 at 16:00 | #10

    @bob
    I doubt it.

  11. bob
    January 28th, 2013 at 15:47 | #11

    hey, do you think when i build your old chassis for this beast, and i replace the 8t gear in a 12t gear, it wil work wel in trtr?

  12. Sariel
    August 20th, 2012 at 01:52 | #12

    @Cody
    Yes, they do.

  13. Cody
    August 20th, 2012 at 00:58 | #13

    Sariel, I have the 9397 logging truck and I was wondering, do linear actuators and mini linear actuators have some sort of safety to prevent breakage from over extension?

  14. Sariel
    February 12th, 2012 at 11:05 | #14

    @me
    Here’s the instruction for the 8297 set, look through the rear axle’s design, it’s all there:
    http://technic.lego.com/en-us/BuildingInstructions/8297%20Group.aspx

  15. me
    February 12th, 2012 at 09:52 | #15

    Sariel :
    @me
    Bricklink.

    me again.
    I want to build a big vehicle with big wheels and full suspended, I know you use special parts for that. What part(s) do you use? What type of suspention do you recommand(6,5L or 9,5L, hard spring, soft spring)?

  16. Sariel
  17. me
    February 4th, 2012 at 12:18 | #17

    @Sariel
    What is the item ID?

  18. Sariel
    February 3rd, 2012 at 18:31 | #18

    @me
    Bricklink.

  19. me
    February 3rd, 2012 at 17:45 | #19

    Where did you get those wheels? I’m searching for really big wheels but I can’t find them.

  20. Sariel
    August 31st, 2011 at 23:39 | #20

    @David
    Apparently not.

  21. David
    August 31st, 2011 at 23:24 | #21

    Why does it sit down on the back axle, aren`t most of the compoents on the middle axle?

  22. shawn
    August 21st, 2011 at 23:10 | #22

    @tom I hadn’t realized just how small the rear compartment was.

  23. tom
    August 20th, 2011 at 22:21 | #23

    @shawn the goal wouldn’t be that it isn’t lego but that the drone is independent from the APC and this would prodably mean that it can’t be fully made of lego because some lego pieces are just larger then they actually need to be.

  24. allu
    August 20th, 2011 at 17:53 | #24

    unimog wheels could be better 🙂

  25. shawn
    August 19th, 2011 at 20:40 | #25

    @tom I would think there’s no reason for a non-lego autonomous rover. Just use Mindstorms.

  26. tom
    August 18th, 2011 at 16:36 | #26

    i like it very much but it would hve been so much cooler if the drone was completely independant from the APC . I know that to do such a thing the drone can’t be fully made of lego pieces but or maybe not at all lego but it still would havenlooked good (just my opinion )

  27. Sariel
    August 18th, 2011 at 08:47 | #27

    @Mecho12345
    They aren’t u-joints. You put u-joints inside them and they protect them from tensions that could damage them.

  28. Mecho12345
    August 18th, 2011 at 06:14 | #28

    i dont have a facebook but i want to comment on your first post on the rg-35
    what do the “Dark Bluish Gray Technic, Steering Ball Joint Large Receptacle” and “Light Bluish Gray Technic, Steering Ball Joint Large Open with C-Shape Pivot Frame” do? are they kind of like u-jointsor what

  29. Sariel
    August 17th, 2011 at 22:59 | #29

    @MeCho123451
    Plain and simple: no space for two.

  30. MeCho123451
    August 17th, 2011 at 22:40 | #30

    why do you only ever use 1 xl motor? 2 would be much more powerful and you wouldn’t need so much gear reduction.

  31. August 17th, 2011 at 13:22 | #31

    My TT had the same setup. The suspension was way too soft, and I didn’t want to spend much money on the big yellow shock absorbers from 8466. Turning radius was quite big, and the steering was too loose. If I tried to climb against a wall, it fell to 1 side, because of the rear steered axle. Link: http://www.flickr.com/photos/luc2000/sets/72157626503017948/with/5621327215/

  32. saberwing
    August 17th, 2011 at 02:22 | #32

    pretty good. had to laugh at how the armor kept falling off. hope the rg 35 works welll

  33. Sariel
    August 16th, 2011 at 23:22 | #33
  34. Mecho12345
    August 16th, 2011 at 23:11 | #34

    I thought the wires were either home-made or from bricklink. What sets are they in?

  35. Sariel
    August 16th, 2011 at 19:42 | #35

    @Robin
    No, I can’t.

  36. August 16th, 2011 at 19:36 | #36

    Hello Sariel,

    I can not see video, because “Unfortunately, this viedeo, which includes music from SME, not available in Germany since the GEMA has the publishing rights are not given here.” could you also please the viedeo on another website and upload dan me write the link? sorry for the poor translator!

    Robin from Germany

  37. Sariel
    August 16th, 2011 at 18:48 | #37

    @jade2448
    Well then, I guess the cost of pieces is under $1,000.

  38. jade2448
    August 16th, 2011 at 18:35 | #38

    I realize that, just I was curious about it.

  39. Sariel
    August 16th, 2011 at 18:23 | #39

    @TLT803
    I’m using rechargeable NiMH AA batteries.

  40. TLT803
    August 16th, 2011 at 17:22 | #40

    I’m sorry this is off topic, but what kind of batteries do you use with a regular PF battery box?

    I ask because a NiMH rechargeable AA is 7g heavier than an alkaline AA. That means a box with NiMH batteries will be 42g heavier. I’m guessing that your MOCs are so strong it doesn’t matter much.

    If you use NiMH the 8110 does tilt noticeably.

  41. TLT803
    August 16th, 2011 at 17:01 | #41

    Beautiful model!

  42. Sariel
    August 16th, 2011 at 15:20 | #42

    @jade2448
    You do realize this is not a set and I’m not selling it?

  43. jade2448
    August 16th, 2011 at 15:00 | #43

    how much do you think this is worth in the US?

  44. will
    August 16th, 2011 at 14:20 | #44

    Cool apc

  45. Sariel
    August 16th, 2011 at 10:19 | #45

    @Mecho12345
    The race is on August 20th, and as for wires – in how many places do I have to write BRICKLINK?

    @shawn
    Of course not, differentials are most needed in steered axles.

  46. Mecho12345
    August 16th, 2011 at 02:10 | #46

    and when is the TrTr race?

  47. Mecho12345
    August 16th, 2011 at 02:07 | #47

    1 meter long wires?!? where did you get those? anyway awesome mocception;)

  48. shawn
    August 16th, 2011 at 01:59 | #48

    Could you get away with using just one diff on the center axle?

  49. Sariel
    August 15th, 2011 at 23:46 | #49

    @Spiller
    There are some WIP photos at my Facebook page, with chassis for instance.

  50. August 15th, 2011 at 23:21 | #50

    Any photos of the internals?
    I happen to be doing something similar, a 6×6 with steering on the font and back axles. NXT project though, some RC programming I guess…

    I wouldn’t feel very secure if the armor suddenly fells off though ; )
    I also like the hamster seat and the mobile drone.

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