Superlube tube

Top right: A possible superlube-tube featuring stratified shear bearings.

Superlube tubes or mechanical cables (in analogy to electrical cables)
are various cable like systems that do capsule transport or other transport
within a cable that has a sheath of stratified shear bearing as an ultra low friction superlubricating layer inside.

Basic properties

Actuation

For getting the contents of the cable/tube to move one might want to integrate shearing drive functionality into some parts of the stratified shear bearings.

One of course can take the traditional approach of only pushing from the source (like with today's pressurized water and gas pipeline systems) Or "push" and "pull" simultaneously at the source side in an unidirectional or alternating way (like today's electrical systems).

With the possibility of the integration of shearing drives though:
For all super lube tubes that carry power in a useful form (thermal is not so useful) there's the opportunity to skim off some of that power and supply it to the these shearing drives. Shearing drives in superlube tube systems

• could be concentrated at special "speed boosting cable sections"
• could be completely continuously distributed over the wohle length of a superlube tube cable

Emulated elasticity

In order for the superlube tube cables to be conveniently handleable
some emulated elasticity needs to be implemented. (Stiff crystal rods would often be rather inconvenient.)

Maybe self-de-twisting?

As for other desirable exotic mechanical metamaterial properties: Cable self de-twisting would be a very convenient property. But that circumferential motion (twist around the cable axis) sounds like horribly complex to design in combination with the stratified shear bearings that run through the cable axially. Well maybe such self-de-twisting capability will de implementable for all kinds of "low" power end-user superlube tube cables.

Concrete examples for superlube tube systems

Superlube tube systems include:

• Chemical energy transmission
• Mechanical energy transmission cables
• Global microcomponent redistribution system
• Diamondoid heat pipe systems
• ...

Due to specialization to their individual tasks these may
differ quite strongly in their specific implementation details.
But the general base idea is the same for all of them.

Distinguishing characteristics for different types of superlube tubes

Size of the transported capsules

• microcomponent size
• ...
• macroscopic

Diameter of the cable

• for home applications (e.g. replacing todays electrical vcables),
• for inter-regional connections (e.g. replacing electrical overland line)

There likely will be a very different scaling law for maximal throughput depending on aerial cable cros-section.
No electrical skin effect making the inner part of a cable ineffective.
In case of viscous flow throughput scales with the fourth power of radius of a hole
Is that maybe even better with stratified shear bearings?
(TODO: investigate that)

Shape of the shear bearings

• thinner or thicker stack(s)
• fully tubular or just rail stripes
• flat of more zig-zag – the latter might be in the case for diamondoid heat pipe systems

Sparse contact bearings

The best lowest friction bearing is no contact or interaction at all.
Unless a spinning ring in outer space this is not possible of course as at least some support is needed.

But supports can be spaced out at least. There is no need for continuous contact along the entire length.
Much like chains only supported by the occasional sprocket.

For an localized infinitesimal bearing support to stay stationary and not shear apart
it needs to loop around in a sort of torodial fashion.
This would be three or more classical roller bearings geometries as the most naive self suggesting approach.

With sparse support sagging and resonance modes become of bigger concern.
Much like with ropes and chains.

Ultimate speed limits

If unsupported (no all around back pressure from outside of the bearings inwards)
then speeds are ultimately limited by the
unsupported rotating ring speed limit or a bit above as it's more like disks.
This is a scale invariant quantity.
Coolability limits might hit earlier though.

If supported and that limit of centrifugal force self destruction further pushed out
then coolability becoming the bottleneck gets more likely.
But honestly at this point the absolute limits are still just subject to wild guessing.

Related

Some superlube tube systems will be designed to carry huge power densities.
See: Power density – and more generally: High performance of gem-gum technology

• How small scale friction shapes advanced transport
• Large scale construction
• Superlube tracks
• infinitesimal bearings
• Unsupported rotating ring speed limit
• Accidentally suggestive