New 12/24 Flat Gear Friction Measurement

[TechnicBrickPower]

The Lego Technic set 42140 App-Controlled Transformation Vehicle introduces two new gears - a flat version of the 12 tooth bevel gear and a flat version of the 20 tooth bevel gear. These gears are designed to have less friction. In this video I measure the difference in gearing efficiency between two gearboxes - one made from a stack of 3 of the original 12 and 20 tooth gears to create a 27 to 125 gearing ratio, and a similar version made from the new flat 12 and 20 tooth gears. The gear box losses are measured using a powered up motor and a powered up App to determined the efficiency of each gear box by lifting different weights. The results are presented and compared for each gearbox.

 

 

[Gray Gear]

Thank you for making this test! I was considering to replace all the bevel gears in my !manual! 1:8 Supercar MOCs with this new version. But according to this the efficiency increase for a drivetrain that has little load and already pretty low friction will be close to zero? A test regarding a low load scenario with high RPM would be interesting for me.

I am currently using the older lbg/lg versions of the bevel gears that had lower friction in comparison to the Tan/black versions. Your test suggets "upgrading" to these will probably be pretty pointless.

[jorgeopesi]

Very interesting thanks for the video.

[Jurss]

Thank You for test?

[howitzer]

Interesting. It appears that while the difference is not that great, it might still be significant for larger/more complex drivetrains as the buildup of friction over many gears becomes a problem and the designer must do everything to minimize it.

[nerdsforprez]

11 hours ago, Gray Gear said:

Thank you for making this test! I was considering to replace all the bevel gears in my !manual! 1:8 Supercar MOCs with this new version. But according to this the efficiency increase for a drivetrain that has little load and already pretty low friction will be close to zero? A test regarding a low load scenario with high RPM would be interesting for me.

I am currently using the older lbg/lg versions of the bevel gears that had lower friction in comparison to the Tan/black versions. Your test suggets "upgrading" to these will probably be pretty pointless.

I agree, probably won't make much difference but I would say that in 1/8 cars there is already quite a bit of load on the drive train.  Especially in TLG official UCS car drivetrains, because they have like a billion gears.   

*break*

Great experiment and interesting results.  

[Gray Gear]

9 minutes ago, nerdsforprez said:

*Snip* I would say that in 1/8 cars there is already quite a bit of load on the drive train.  Especially in TLG official UCS car drivetrains, because they have like a billion gears.     

Yes, for most 1:8 supercars you are probably correct, I would do the change for the cars with 8 speed sequential transmissions. But my MOCs all have a 6 speed manual transmission, which has a lot less resistance due to much more efficient construction, and only 1 gear ring being engaged at all times. If you push my cars they keep on rolling quite a bit ,even in 1st gear.

[markaus]

i assume the motor torque is being recorded by the hub, is that averaged over the 0.8s or the maximum value? You also dont seem to make use of the motor RPM once calculated so i guess that was just there for fun. Based on the equations you used for efficiency the motor angle cancels out from both terms (assuming non zero motor angle) so you're really just looking at mass*radius*g / motor torque. Given that the top term is just some constant for both gear types in any given mass test you may aswell just ignore its value too and just directly compare motor torque recorded for each gear type. A reduction gear train isnt generally where you notice issues with the bevel gears anways. Try the unofficial test again but measure the torque required to spin each one and then compare those. Could try a longer gear train with a few alternating or neutral ratios so the final ratio isnt too much to stall the motor.

[gyenesvi]

Interesting test, thanks for doing it, I'd also suggest trying it the other way round with the gearing (up-gearing) to see how that effects the results!

[amorti]

Interesting test, and extremely thorough as always!

The gearbox you constructed for this is (within the bounds of ABS plastic) very sturdy. I suspect there would be more difference in a less-rigid gearbox, where the gears would be more able to rub the adjacent liftarm. Also more difference in a construction where the typical user might pinch a gear too tight?

[Lipko]

Wow I didn't even know about these new gears...

[Zerobricks]

I have a feeling that because the upcoming Ferrari is RWD only, they had only half the available torque to drive the gearbox and the engine and this was one of the solutions used to reduce the friction.

[Gray Gear]

It could also be because they encountered an engagement problem somewhere. I had the problem in setup like this before that the two bevel gears would engage as well sometimes, which is obviously a problem.

[Andman]

Thanks for the Video and the test! But I think it highly depends on the mould of the bevel gears. All of my grey 20z bevel gears work fin. Every other color version causes sometimes issues. Especially the tan one. Sometimes only one side of the 20z gear is rubbing against liftarms and sometimes both sides. Seems like it depends on fractions millimetres, if they introduce more or less friction.

So did you test your chosen bevel gears, if they are grinding against liftarms?

[Gray Gear]

@Andman Yeah thats was my take as well. Conpared to the old lg/lbg bevel gears these new ones are probably needed, since those were close to perfect. But compared to the newer Tan/Black versions these new ones are probably a noticable improvement.

[Axadder]

Great and smart work!

[Zerobricks]

Another good usage of the new 12 tooth gear is for steering mechanisms, there is visibly less slack and better engagement with the rack.

[gyenesvi]

47 minutes ago, Zerobricks said:

Another good usage of the new 12 tooth gear is for steering mechanisms, there is visibly less slack and better engagement with the rack.

That sounds really good, although I thought that the bevel version was already quite good there. Curious to try this once I get my hands on those gears!

[msk6003]

Quite interesting. I did simple test with new gear but numerical output is another story.

If anyone interested my simple experiment, see this.