My daughter got the LEGO Technic - Service Truck set. When we looked at the instructions, we saw a different notation on parts.

eg: the beams (cross beam) it has number 5 in white circle. what does that 5 stand for. Other instructions in same book have the number 3 or 7 in white circle.

Can anybody advise what these numbers mean?

2 Answers 2


Beams, axles, panels, and axles connectors usually have numbers next to them, to uniquely identifies the piece:

  • for beams and axles, the number is the length (length in number of holes)
  • for panels, it identifies the panel (and the panel mold contains the same number)
  • for axle connectors, it identifies the angle (again, the same number is part of the mold, and visible on the piece)

Same pieces with different colors have the same number attached


These numbers indicate the length of the beam or axle shown.

For a beam, this number is the number of holes it has. For an axle you have to hold it next to a beam and than count the number of holes.

  • 4
    Also, the instructions usually have a 'ruler' on that page of instructions so you can measure it even without a beam or brick of that length.
    – gev
    Commented Nov 23, 2014 at 10:25

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