6

from to this question, it seems that the gears are stronger than the axles, which begs the question of how strong are the axles? if you connect one of the stronger motors, such as say the buggy motor:

http://www.bricklink.com/PL/5292.jpg

which according to philohome can produce 14N*cm of torque with an adequate power supply, is this enough as-is to break axles? what if it's geared down 1:2? 1:4? (such that it turns slower with more force), at what point do you risk breaking axles? (or more likely, at which point will they start to bend and lose strength)

4

In this forum thread I have found the following tidbits:

  • "We all know that XL motors can twist axles to their breaking point" This means 40 Ncm, according to Philo.
  • "If you're looking to get max torsional stiffness, then stacked 2L axles + connectors would definitely be much stiffer in torsion than a single long axle."
  • Axles can twist without breaking in two

Besides these, I couldn't find an exact number.

2

I have never broken an axle. That's despite dealing with some rather hefty forces that dwarf any LEGO motor. I made a flywheel (around 800g and 8cm radius) and spun it by hand up to 1,000 RPM (through a gearing system and a monstrous handle). That's 28 joules of kinetic energy there. I then released it all into a single wheel (with more gearing up), with the drive passing through A SINGLE axle. The axle was only slightly bent, and could easily be twisted back.

On another note, I often use torsion bars as shock absorbers in my vehicles when I need a compact double-wishbone suspension. A 1.5kg vehicle provides enough weight to twist eight 7-stud axles by around 5-10 degrees.

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