This DIY pressure wave gearbox is powerful sufficient to tug a automobile

Mechanical benefit is arguably a very powerful engineering idea that humanity has ever discovered to harness. By changing distance, just like the size of a lever or rotations of a gear, into torque (and vice versa) we are able to overcome nearly any bodily problem. However that distance could be a difficulty. For instance, you probably have an enter gear 10mm in diameter and need a 100:1 discount, your output gear must be a full meter in diameter. Pressure wave gearboxes clear up that downside and Brian Brocken’s video will stroll you thru the best way to construct your individual that’s sturdy sufficient to tug a automobile.

To keep away from meter-wide gears, engineers sometimes flip to gearboxes that incorporate a number of gears. Every gear multiplies the discount of the previous gear, so a number of gears can obtain dramatic reductions and one can organize them in a compact house. However a pressure wave, AKA “harmonic drive,” gear can obtain an analogous discount with simply three elements: a wave generator, a flex spline, and a round spline. 

The round spline is the outermost half and has inside gear tooth of typical geometry. The flex spline meshes with that round spline, however solely at two reverse factors. The wave generator, which is the enter and innermost half, has an rectangular form and forces the flex backbone’s tooth into contact with the round spline. This odd association causes the flex spline to push the round spline ahead by round one tooth per full revolution, leading to an enormous discount. Brocken’s design produces a discount of 54:1, which is unimaginable for the scale. As a result of there are solely two factors the place the gear tooth mesh, this produces much less friction than a typical gearbox and has tighter tolerances due to the shortage of substances backlash.

A lot of the mechanical elements for this pressure wave gearbox are 3D-printable, however you’ll want a option to management the DC motor that drives the gearbox. Brocken used an Arduino Nano board that matches onto a customized energy distribution PCB. With that, Brocken can use a big energy provide and permit the Nano to manage a lBT2 H-bridge motor driver that handles as much as 43A. Utilizing a standard brushed DC motor, this gearbox can produce about 3.75N*m. That’s just like an 79cc inner combustion engine and is sufficient to pull a Dodge Charger throughout a flat floor.