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Author Topic: How can this driveshaft work?  (Read 8369 times)

Offline Geezer

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How can this driveshaft work?
« on: 01/04/2010 04:33:50 »
Any ideas about how this works?



 

Offline doppler1

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How can this driveshaft work?
« Reply #1 on: 01/04/2010 06:20:45 »
Hey Geezer, That is one cool drive. I would say that it is driven using a closed hydraulic system. The drive that is connected to the lathe turns and drives mechanical bidirectional impeller. As the impeller turns, the oil is displaced through the pipes and then acts on an impeller on the other side and turns the other end with the same speed, direction and directly proportional power.....well that's just how I would do it but I could be wrong.
 

Offline LeeE

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How can this driveshaft work?
« Reply #2 on: 01/04/2010 17:14:49 »
The description by the person who posted the vid says:

Quote
High Torque Flexible Drive Shaft Constant Velocity Driveshaft with Disconnect Feature Hydrostatic Hydraulic Synchronous
 

Offline Geezer

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How can this driveshaft work?
« Reply #3 on: 01/04/2010 17:26:32 »
The description by the person who posted the vid says:

Quote
High Torque Flexible Drive Shaft Constant Velocity Driveshaft with Disconnect Feature Hydrostatic Hydraulic Synchronous

Sounds like mumble speak to me. That does not say much about how it really works. I think they were just trying to get the maximum number of web hits.
 

Offline LeeE

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How can this driveshaft work?
« Reply #4 on: 01/04/2010 23:41:20 »
Umm, yes... they'll be the relevant keywords.  If they were just trying to get the maximum number of web hits then they would have used pron keywords.  I think you're just being a bit too paranoid here.
 

Offline RD

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How can this driveshaft work?
« Reply #5 on: 02/04/2010 00:33:40 »
Is it really truly synchronised ? (i.e. like gears).
If a heavy load was applied I suspect the two rotations would not keep perfectly in sync.

« Last Edit: 02/04/2010 03:32:18 by RD »
 

Offline Geezer

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How can this driveshaft work?
« Reply #6 on: 02/04/2010 04:18:13 »
Is it really truly synchronised ? (i.e. like gears).
If a heavy load was applied I suspect the two rotations would not keep perfectly in sync.



I suppose there would have to be some amount of phase shift under load, particularly of it's a hydraulic connection. The fluid must compress a bit and the hoses are going to expand slightly too. Mind you, I suppose any drive shaft allows some amount of phase shift under torque.

It looks like there are three hoses. I wonder what that's all about? Hydraulic motors only need two.
 

Offline LeeE

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How can this driveshaft work?
« Reply #7 on: 02/04/2010 14:20:08 »
Is it really truly synchronised ? (i.e. like gears).
If a heavy load was applied I suspect the two rotations would not keep perfectly in sync.

Yes, I agree.  If it's really a hydrostatic link then the input and output can't be perfectly syncronised.  Hmm... unless that third hose is there for syncronisation purposes (but I'm not sure how that would work either).
 

Offline Geezer

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How can this driveshaft work?
« Reply #8 on: 03/04/2010 00:25:46 »
Umm, yes... they'll be the relevant keywords.  If they were just trying to get the maximum number of web hits then they would have used pron keywords.  I think you're just being a bit too paranoid here.

Just because I'm paranoid, it doesn't mean they are not out to get me.

BTW, 'scuse my ignorance, but what's a "pron keyword"?
 

Offline RD

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How can this driveshaft work?
« Reply #9 on: 03/04/2010 00:28:11 »
'scuse my ignorance, but what's a "pron keyword"?

Try anagrams of "pron".
 

Offline Geezer

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How can this driveshaft work?
« Reply #10 on: 03/04/2010 00:40:57 »
LOL! Thanks!
 

Offline Geezer

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How can this driveshaft work?
« Reply #11 on: 05/04/2010 22:12:42 »
I think it may be something similar to this.

http://www.google.com/patents/about?id=6C8AAAAAEBAJ&dq=6837141
 

Offline peppercorn

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How can this driveshaft work?
« Reply #12 on: 06/04/2010 15:17:05 »
Can this type of actuator be driven from a pneumatic accumulator acting on three hydraulic pistons (timed to copy the linear displacement of a driving rotor)?

If so it would seem a perfect transmission system for a free-piston powered series-hybrid vehicle (providing this type of drive could take the torque).
 

Offline Geezer

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How can this driveshaft work?
« Reply #13 on: 06/04/2010 19:00:56 »
Can this type of actuator be driven from a pneumatic accumulator acting on three hydraulic pistons (timed to copy the linear displacement of a driving rotor)?

If so it would seem a perfect transmission system for a free-piston powered series-hybrid vehicle (providing this type of drive could take the torque).

I suppose it could. It would probably have to produce three sinusoidal pressure relationships to mimic the hydraulic response of one end.

My initial reaction was "why bother" because, if you could produce those relationships with compressed air, you might as well use them to drive the "motor" directly and dispense with the hydraulics.

However, that would depend on how large the "motor" was allowed to be. The hydraulic form should be able to produce a much greater torque than an air motor of equivalent dimensions. Of course, it would be necessary to have "pressure multipliers" to convert the low pressure air phases into high pressure fluid phases.
 

Offline LeeE

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How can this driveshaft work?
« Reply #14 on: 06/04/2010 23:23:14 »
Can this type of actuator be driven from a pneumatic accumulator acting on three hydraulic pistons (timed to copy the linear displacement of a driving rotor)?

If so it would seem a perfect transmission system for a free-piston powered series-hybrid vehicle (providing this type of drive could take the torque).

I don't think so.  A piston type arrangement with just three channels (tubes) would result in three clear lobes on the output plot (unless there was some sort of buffer reservoir to smooth the pulsed output. And even then, 120° is still a bit too much for a passive buffer reservoir to cope with).

Another way of looking at such a pulsed solution is to consider the bandwidth of the solution.  Let's say that this connection can handle up to 100rpm (which is relatively low-speed).  Even if there is just a single pulse on each actuator, then for each revolution we're looking at a total of 300 pulses per minute, which means that the equivalent mass of three times the body/mass of hydraulic fluid in one tube must be accelerated and then deccelerated for each revolution i.e. 3 * 100 times, from a single power source; this strikes me as a huge energy loss.
 

Offline Geezer

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How can this driveshaft work?
« Reply #15 on: 07/04/2010 05:10:14 »
Can this type of actuator be driven from a pneumatic accumulator acting on three hydraulic pistons (timed to copy the linear displacement of a driving rotor)?

If so it would seem a perfect transmission system for a free-piston powered series-hybrid vehicle (providing this type of drive could take the torque).

I don't think so.  A piston type arrangement with just three channels (tubes) would result in three clear lobes on the output plot (unless there was some sort of buffer reservoir to smooth the pulsed output. And even then, 120° is still a bit too much for a passive buffer reservoir to cope with).

Another way of looking at such a pulsed solution is to consider the bandwidth of the solution.  Let's say that this connection can handle up to 100rpm (which is relatively low-speed).  Even if there is just a single pulse on each actuator, then for each revolution we're looking at a total of 300 pulses per minute, which means that the equivalent mass of three times the body/mass of hydraulic fluid in one tube must be accelerated and then deccelerated for each revolution i.e. 3 * 100 times, from a single power source; this strikes me as a huge energy loss.

I don't think the flow is so much pulsed as sinusoidal. It seems to be somewhat analogous with polyphase electrical systems.

Accelerating the mass of fluid will consume energy, but that energy should be recovered when it acts on the other end and decelerates. I suppose it's a sort of reciprocating mass. Of course, if the fluid flow rate is too great, a lot of energy could be wasted in fluid friction in the tubes, so things would have to be sized properly to take that into account.

Mind you, if you tried to run it too fast, I imagine the whole thing might just resonate. It's probably best suited to low speeds and high torques.
 

Offline doppler1

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How can this driveshaft work?
« Reply #16 on: 13/04/2010 13:34:14 »
I agree that this is for a relatively slow RPM system.....still pretty cool though. I recon that the concept of having a flexible and self contained transfer system like this has plenty potential and can be improved upon, as far as the speed is concerned, with some of the brain being flexed in the right direction.
 

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How can this driveshaft work?
« Reply #16 on: 13/04/2010 13:34:14 »

 

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