Improved theory automatic gearbox

[TechnicBrickPower]

Hi All,

This video demonstrates an improved design of a 2 speed automatic gearbox based on a theoretical approach. Typically a Lego automatic gearbox consists of two stages namely a gear selector and a torque detector. In this video, both of these components are improved upon. The gear selector gear count has been reduced from 13 gears down to just 9 gears and a torque improvement of 40% is demonstrated via pulling on rubber bands and measuring the force using luggage scales. The torque detector is analyzed mathematically and the equations determining it's gear ratio behaviour are presented. Finally the overall improved automatic gearbox is tested and demonstrated to have a powerful second gear.

 

 

[2GodBDGlory]

Good work!

It is still much too large for easy use in a scaled model, but I know that isn't the point.

It has been very interesting watching you develop the theory and then put it into practice.

[nerdsforprez]

I like these builds, especially in a time where there is concern of over-saturation of the MOC market, or even Technic line, of certain vehicles.  Concepts such as these, mechanisms only, Akiyuki machines, etc. all branch the hobby outward...

 

[Andman]

I love your scientific approach on Lego! Very interesting!

[Woodpecker]

Why do you have to multiply everything by a factor of two to calculate the gear ratio when dealing with a differential?

[TechnicBrickPower]

18 hours ago, Woodpecker said:

Why do you have to multiply everything by a factor of two to calculate the gear ratio when dealing with a differential?

HI Woodpecker. Yes good question - I didn't explain that very well in the video. The reason is that the center of the differential rotates at the average speed of the two side inputs. So mathematically we have C = (A+B) / 2. Now because I drive the center C in my layout the equation becomes A = 2C -B. So the 2 in the 2C is where the factor of 2 comes from. Hope that makes sense.

[Woodpecker]

Thanks TechnicBrickPower; your explanation made sense. Very helpful. I will use those equations to calculate the gear ratios in my six speed gearbox that uses a differential.