View source for Atomically precise roller gearbearing

'''Up: [[Atomically precise bearings]]'''

Atomically precise roller gearbearings are bearings with:
* all surfaces being atomically precise and nonreactive (See: [[nanoscale passivation]])
* roller having gear teeth
* dry running – no lubricants
* atomically tight seals

'''Why not smooth ungeared rollers?''' Because:
* low resistance against slipping at the nanoscale may cause hard to predict behavior including sliding of rollers. 
* no slipping implies interdigitation at the nanoscale and atomically precise interdigitation implies well defined gears
<small>As a side-note: FFF printed bearings also typically work better as gearbearings. <br>
There the reason is that static friction from material-to-material contact is often lower than forces from hookups on printing-inaccuracies like layerchange-blobs, non-roundness, or something else. <br>
And thus ungeared rollers tend to start to slide and consequently self destruct. </small>

'''Why no lubricants?''' Because: <br>
The atoms of lubricants are like grave at the nanoscale and <br>
atomically precise surfaces of [[Base materials with high potential|''good'']] [[gemstone like compounds]] feature:
* [[FAPP]] no [[wear]] (no structural irreversibility) and 
* low dynamic friction for low sliding speeds – (there is a tiny bit of sliding in rolling gears) 
See sections below for details.

== Types == 

== Shapecomplementary atomic teeth gearbearings ==

Here protruding atoms act as gear teeth addenda and  <br>
the trough spaces between act as gear teeth dedenda. <br>

* For cylindrical rollers atoms can be arranged in rows or spirals. <br>
* For conical rollers rows or spirals are not an option as the teeth <br>continuously and slowly would vary in width which atoms can't.

Some prototypes have been modeled theoretically via means of molecular dynamics modelling.

See: [[Examples of diamondoid molecular machine elements]]

'''Naming:''' How about "Countertomic rollerbearings"?

== Superlubricating toothflank gearbearings ==

Conventional gear teeth profiles are approximated. Cycloid, Evolvent, or other.<br>
Very much conventional gears. <br>

When tooth flanks contact then ideally the atomic bumpyness is as imcommensurable as possible. <br>
Such design leads to [[superlubricity]] when tooth-flanks rub more or less forcefully along each other ([*|accidentally suggestive]).

Flank shapes can be approximated by [[strained shell structures]]. <br>
Where the outer surface is undisturbed lattice and the inner structure <br>
contains intentional defects similar to the principle of [[Kaehler bracket]]s.

Getting smooth flanks near enough the mathematic ideal such that <br>
the elastic surface-surface interactions can do the rest works better for bigger gears. 

Even "graphene-sheet-lining" could perhaps be an option maybe. See: [[nanoscale passivation]] for that.

Smaller gears (filling the size gap down to Shapecomplementary atomic teeth gearbearings) <br>
By only crudely approximating shape [[Kaehler bracket]] style might <br>
get a bit rough in operation meaning large remaining energy barriers during rotation. <br>
Thus they may be less desirable.

'''Naming:''' How about "SuToFlaGe bearings"?

== Lower friction at higher speeds ==

While [[Atomically precise slide bearing]]s can be <br>
very compact and feature extremely low energetic friction losses for very small speeds  <br>
losses are not low for moderate speeds and it gets really bad for high speeds. <br>

But looking how efficient macroscale bearings can be for high speeds this is unsatisfactory. <br>
As roller (gear)bearings are a direct analogy they should be able to allow significantly lower losses at higher speeds. <br>
This works by two effects:
* Lower sliding speeds – teeth in gears still slide but much slower than speeds in a sliding bearing
* lower contact area – there's no point contact because of elastic deformation

Note that:
* the lower contact area reduces load bearing capacity
* the (necessarily atomically tight) seal still contributes to sliding friction – quadratic
* contact area reduction only linear

At the cost of high design effort going for [[infinitesimal bearings]] reduces losses quite a bit. <br> 
Roller gearbearing based infinitesimal bearings will likely be much preferrable over sliding infiniresimal bearings. <br>
Infinitesimal bearings need rollers to distribute speeds equally anyway.

See main pages: [[Friction in gem-gum technology]], [[Friction]]

== Wear ==

Since surfaces are assumed atomically precise after production
and materials are assumed extremely hard. Typically Mohs 8 and above.

The only modes of damage are:
* via sufficiently ionizing radiation (and degradation from there) – a hit can be quite the "nano-nuke" <br> "sufficiently ionizing" means UV may not be high energy enough
* significant thermal overload (melting)
* significant mechanical overload (total crush)
* dissolution by very aggressive chemicals - if the chemical manages to breach the seal
* a combination of the above

If properly built with atomically tight seals then potentially damaging nanoscale dirt can't get in.

== Sealing & dirt ==

Especially bigger atomically precise gear-bearings have hollow spaces where dirt could find place obstructing motion and leading to damage. <br>
(Note that as these are gearbearings no cages for rollers are needed.)
----
The assumption is though that atomically precise seals get included <br> 
compartmentalizing space and thereby:
* making a [[PPV]] possible and 
* leaving not a single stray gas molecule in. 
----
As for dirt from hard ionizing radiation splitting it off from AP surfaces: 
* This should be covered by system redundancy and
* eventual [[selfrepair by subcomponent replacement]] (hot plugging or not).

The smaller the system the less room there is for undetected slight damage. <br>
Either it works or it does not.

On the other hand the bigger the system the more there is space for undetected slight damage. <br>

There is likely a sweet spot at quite small scale with
* very low degradation
* already low friction for higher speeds

Related: [[Vacuum lockout]]

== Relation to atomically precise gears ==

Gears are basically the same.
Geometry of loads is typically different which may reglect in specific designs.

== Tooth profiles ==

For gearbearings (full) cycloid profiles seem good? <br>
* Cycloid gears have flank lower sliding speeds than evolvent gears and are known for their low friction properties.
* The varying pressure angle of cycloid flanks is less problematic in the absence of tangential loads as present in gear-trains <br> helical tooth trajectories can further help there
* Full cycloid profile gears  can be pressed together reducing backlash to zero by pre-tension. <br> Evlovent flanks need high pressure angles for that and incur more sliding speed

== Conductive roller gearbearings ==

For motors and generators conductive rollers should give <br> 
notably lower losses than using tunnelling contacts.
 
See: [[Electromechanical energy conversion]]

== Related ==

* [[Superlubricity]]
* [[Infinitesimal bearings]]

== External links ==

* [https://en.wikipedia.org/wiki/Gear_bearing Gear bearing]
* [https://en.wikipedia.org/wiki/Needle_roller_bearing Needle roller bearing]