Hydraulic Generators

[pnichols]

I notice that the newest high end Earthroamer has a hydraulic generator on board.

I know that Earthroamer likes to talk about their vehicles not having onboard stand-alone generators. So I wonder what the RV advantages are of a hydraulic generator over a conventional stand-alone generator?

Doesn't a hydraulic generator require the main vehicle engine to be idling to run it's PTO to power the hydraulic generator? If so ... isn't high-idling of the Earthroamer's diesel engine going to be somewhat noisey and smelly .... just like with a conventional diesel generator (plus use more fuel than a small stand-alone generator)?

Here's a link to a typical hydraulic generator product that might be what Earthroamer is using: http://harrisonhydragen.com/?page_id=90

[Horizon170]

theoldwizard1 wrote:

MrWizard wrote:
run the drive engine, to power a hydraulic pump , too spin a generator

something here doesn't make sense to me

1st and 2nd Law of Thermodynamics.

When you convert one form of energy to another, you can't win. You can't even "break even".

Not trying to argue but most train engines are Diesel over Electric I think.
I would NOT want this setup.
Marvin

[Chum_lee]

drsteve wrote:

DrewE wrote:
If only there were some mechanical method to increase rotational speed and allow high speed devices to be operated by lower speed motors....

I have heard rumors that such technology exists... I'll have to Google it.

They're economical, compact, and they can handle high loads. They've been around and used successfully for years. I'll gladly save you the time/trouble googling it. It's called a . . . . planetary gearset. Typically they are used for gear reduction, but they don't have to be.

Chum lee

[SidecarFlip]

MrWizard wrote:
doesn't need to be governed
IF
they use a pump powered multiphase alternator head and inverter electronics ?

i think this is a case of a solution looking for a problem
like one post suggested "cost is no object, its about bragging rights"

That was me. Now, if someone gave me one (Earth Roamer), I'd be happy to use it as an RV, but buy one, no way. Just a status symbol for the well to do set.

[MEXICOWANDERER]

10" driver - 2" driven

Pulleys

One will get you five...

[drsteve]

DrewE wrote:
If only there were some mechanical method to increase rotational speed and allow high speed devices to be operated by lower speed motors....

I have heard rumors that such technology exists... I'll have to Google it.

[MEXICOWANDERER]

I like my own personal natural gas field and 1 Megawatt Worthington natural gas generator to sell power back to the utility. With enough dehumidifiers, I could get structure humidity down to 20% with 22c. Even the garage which houses my Rolls extended chassis and Oshkosh touring rig.

Nice to dream. I was forced to use a hydraulic test bench to test alternator output curves from 500 RPM to 3,000 RPM. The winner was my 50DN Delco that develops 80 amps at 500 ALTERNATOR RPM.

[DrewE]

If only there were some mechanical method to increase rotational speed and allow high speed devices to be operated by lower speed motors....

[MrWizard]

we had hydraulic pumps on industrial CNC machinery

the max speed those motors ever ran was 1875 RPM
and may have been as low as 1200 rpm

[time2roll]

MEXICOWANDERER wrote:
And hydraulic motors do not like to spin at 5K RPM

Generators are fine at 1800 rpm. Maybe less if you add a couple more poles.

[pnichols]

According to an Earthroamer XV-HD video I just watched, the way it utilizes the hydraulic generator is to automatically sense when the battery bank is low, then automatically start up the diesel chassis engine to power the hydraulic generator until the the battery bank is fully charged, at which time the diesel engine is automatically shut down. This appears to be much the same procedure as the way certain Class A motorhomes handle automatic start-up/shut-down of their built-in fossil fuel generators to automatically recharge their battery banks as needed.

Earthroamer engineers seem to be really hung up with not having a conventional stand-alone diesel generator on board. I have been camped next to well engineered Class A motorhomes with their generators running that I could - for all practical purposes - "not hear". I walked up to within 6-8 feet of one in order to try and hear it's built-in generator quietly humming along ... really, really not irritating at all - way quieter than a Honda inverter generator at idle.

So .... ultra-quiet built-in RV fossil fuel powered 120V AC generation IS POSSIBLE. Earthroamer engineers should know that. That being given, they may be using PTO and a hydraulic generator because:

1. A hydraulic generator can be broken up into two very small pieces for better fit in tight places -> pump at the PTO point with the generator unit tucked away some place else.

AND/OR

2. Believe it or not - MAYBE modern fossil fuel large bore chassis engines now emit less smelly fumes into the air than any available fossil fuel powered small generators.

[DrewE]

GordonThree wrote:
Wouldn't they have the same problem with a hydro system as well, unless they're using an electric pump instead of a belt drive? With gearing, belts, etc they can convert rpms up or down, but it still needs to be constant, still needs to be governed somehow?

I think they can govern it by altering the hydraulic fluid flow. I'm no expert, not even close, but I'm under the impression that many hydraulic systems are set up to operate at a more or less constant pressure (at least a constant static pressure), with something along the lines of a bypass valve at the pump end. If the load on the system is not constant, something of that sort is required or the pump would be locked and unable to turn until something broke loose...with messy results.

An inverter generator setup could certainly be used on a PTO or belted from an engine. At that point, it might be just as simple to put in a bigger alternator and an ordinary inverter, which amounts to much the same thing after all.

[MrWizard]

yeah that 'could' be done

but does the earth roamer have a PTO ?

i think this whole discussion is showing the reasons, why the idea is expensive and maybe ? ridiculous

[GordonThree]

MrWizard wrote:
doesn't need to be governed
IF
they use a pump powered multiphase alternator head and inverter electronics ?

i think this is a case of a solution looking for a problem
like one post suggested "cost is no object, its about bragging rights"

If we're going exotic, wouldn't the same inverter-generator setup work off the pto or accessory belt? The inverter electronics could talk to the engine computer and request whatever RPM it needs to deliver the requested current.

[MEXICOWANDERER]

All of Quicksilver is a 24 volt system. Chassis and coach.

And I am out of pulley room for the crankshaft. About 7/8" to a major crossmember.

If I wanted to have a 12-volt alternator too I would be out-of-bullets.

I would have to install a hydraulic pump and run it off the Fuller transmission.

Which would allow me to place the new alternator anywhere within reason in the engine bay.

Top drawer hydraulic systems are EXpensive! A quality pump with magnetic clutch alone costs in excess of $1500

And hydraulic motors do not like to spin at 5K RPM

So an 8-9/16" frame low-speed alternator would be de riguer. Two thousand for that puppy. Then there is the motor. And #10 double braid hoses.

Sooner or later it's going to start dripping hydraulic fluid.

Even if someone else was footing the bill it would take a lot of fast talking to get me interested in a hydraulic driven alternator.

Thirty seven years ago I spent $12000 building a 10HP hydraulic alternator test bench. Fifteen years later it started dripping.

No thanks