8hp vs 16 hp

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Nik3v
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8hp vs 16 hp

Post by Nik3v » Tue Jan 15, 2019 11:55 pm

Probably not enough info, but in a generic way in 1.5 scale how much difference does it make?
I have a PA that is set up with twin 8hp kohler engines driving twin hydraulic pumps which come together in a tee before passing through the valve and on to the truck mounted motors.
My track is not ready for serious testing but 1 car trials show no noticeable difference with one engine shut off. I’d say I’m losing half, but I think it’s less than that with the pumps fighting each other.
Removing one motor and pump would sure simplify things. Control wise for sure.
Before you ask I’m away from home and can’t give you pump flows or numbers.
Any thoughts!
Nik3v

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BigDumbDinosaur
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Re: 8hp vs 16 hp

Post by BigDumbDinosaur » Wed Jan 16, 2019 2:35 am

Nik3v wrote:
Tue Jan 15, 2019 11:55 pm
Probably not enough info, but in a generic way in 1.5 scale how much difference does it make?
I have a PA that is set up with twin 8hp kohler engines driving twin hydraulic pumps which come together in a tee before passing through the valve and on to the truck mounted motors.
My track is not ready for serious testing but 1 car trials show no noticeable difference with one engine shut off. I’d say I’m losing half, but I think it’s less than that with the pumps fighting each other.
Removing one motor and pump would sure simplify things. Control wise for sure.
Before you ask I’m away from home and can’t give you pump flows or numbers.
Any thoughts!
Nik3v
I'm going to hazard a guess and say that the teeing of the two pumps' output is consuming much of the available horsepower, which is why you aren't seeing a lot of difference with one engine dead. Without going into a lot of fluid mechanics theory to explain my guess, try to visualize what happens when fluid (oil in this case) rushing into one branch of a tee at velocity V encounters fluid rushing into the other branch of the same tee and also at velocity V. You could also stage a cornfield meet on your railroad to illustrate the problem. :D

In any case, 8 horsepower is probably more than adequate, unless you plan to haul scale 100 car coal trains.
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Berkman
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Re: 8hp vs 16 hp

Post by Berkman » Wed Jan 16, 2019 10:59 am

Could always replace the dual system with one 16 hp twin V setup. eaton hydraulic systems are pretty robust. Likely this would provide more usable power and consume much less fuel, potentially be much quieter as well. Even the largest 1.6 scale diesels generally just have one motor/hydraulic system and typically 16hp is more than enough.

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BigDumbDinosaur
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Re: 8hp vs 16 hp

Post by BigDumbDinosaur » Wed Jan 16, 2019 11:58 am

Berkman wrote:
Wed Jan 16, 2019 10:59 am
Even the largest 1.6 scale diesels generally just have one motor/hydraulic system and typically 16hp is more than enough.
What do you mean by "one motor/hydraulic system?"
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Berkman
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Re: 8hp vs 16 hp

Post by Berkman » Wed Jan 16, 2019 12:27 pm

sorry wasn't clear. Meaning one gas engine connected to one hydraulic pump with one set of controls.

It certainly is not typical to have multiple "prime movers" set up with multiple hydraulic pumps. There doesn't seem to be any reason to go this route.

Now i've also heard of variations in how the hydraulic motors are mounted, whether on the trucks or a single large one in the body then drive shafts running to the trucks.

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Re: 8hp vs 16 hp

Post by rkcarguy » Wed Jan 16, 2019 1:52 pm

I agree with BDD, the 2 pumps into one "Y" is likely choking off the flow and much of the 2nd engine/pump is going to be wasted power unless the Y and the hoses after it are all larger, as are the hydraulic motors(doubtful). If you are happy with the performance on one engine/pump, I don't see any reason to use both.

Nik3v
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Re: 8hp vs 16 hp

Post by Nik3v » Thu Jan 17, 2019 12:12 am

5D57CDF1-ABB9-4922-8D66-25B188C7C063.jpeg
Yeah I didn’t think it necessary. Well built I guess but will gain a lot of real estate taking one motor and pump unit along with hoses out.
Here’s a photo. Both pump outputs to a cornfield meet in a 1/2 tee. Tee feeds an electric proportional control valve that feeds the forward neutral reverse valve. Much easier planning for 1 throttle
Thanks for the opinions
Nik3v

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Re: 8hp vs 16 hp

Post by spro » Thu Jan 17, 2019 7:03 am

It looks pretty neat to me. Proportion valves also suggest either engine could supply power. As robust as the Kohler 8 hp is, what if it blows a gasket in the middle of a run? It would be super to have the emergency engine. Perhaps some sections were replaced that would have isolated them. fjwtss :)

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Re: 8hp vs 16 hp

Post by Bob D. » Thu Jan 17, 2019 8:09 am

Those motors sure aren't happy with no air filters....
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Nik3v
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Re: 8hp vs 16 hp

Post by Nik3v » Thu Jan 17, 2019 11:41 am

Air filters are on the list. There are intake openings in the body opposite the carbs. At the very least I can sandwich some filter media in there. I could put in valves to isolate either engine. Not sure I need valves as I’m not sure fluid will pass through the vanes
on the pumps backwards.
My biggest issue with both engines is coming up with a handheld throttle to run both evenly.
Proportional valve may have been the wrong word. It is a brand hydraulics electronic variable flow control valve. Makes it handheld with a dial for speed.
Nik3v

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BigDumbDinosaur
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Re: 8hp vs 16 hp

Post by BigDumbDinosaur » Fri Jan 18, 2019 2:01 am

Nik3v wrote:
Thu Jan 17, 2019 12:12 am
5D57CDF1-ABB9-4922-8D66-25B188C7C063.jpegYeah I didn’t think it necessary. Well built I guess but will gain a lot of real estate taking one motor and pump unit along with hoses out.
Not to be too pedantic, but the correct term for those two oily things with the fins that make noise and horsepower is "engine," not "motor." :D

In mechanical engineering, a machine that converts the chemical energy of fuel into kinetic energy is called an engine or prime mover. A machine that converts potential energy to kinetic energy is called a motor. In the electrical propulsion system of a Diesel-electric locomotive, the traction generator converts most of the prime mover's kinetic energy into potential energy. The traction motors reverse the process.
Here’s a photo. Both pump outputs to a cornfield meet in a 1/2 tee.
Whomever plumbed that was awfully brave—or naive. Schedule 40 pipe fittings are not rated for the pressures generated in hydrostatic power transmission systems. Real hydraulic fittings are manufactured from forged blanks, not iron or semi-steel castings.
spro wrote:
Thu Jan 17, 2019 7:03 am
As robust as the Kohler 8 hp is, what if it blows a gasket in the middle of a run? It would be super to have the emergency engine.
I have never seen any iron block Kohler engine blow a head gasket—and I have been using and abusing one cylinder engines since the late 1950s. The only Kohler I ever destroyed was one in which I had defeated the governor. I don't know what kind of RPM the engine was turning right before everything came unglued, but it sure sounded sweet. :D
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Re: 8hp vs 16 hp

Post by Harold_V » Fri Jan 18, 2019 2:26 am

BigDumbDinosaur wrote:
Fri Jan 18, 2019 2:01 am
Not to be too pedantic, but the correct term for those two oily things with the fins that make noise and horsepower is "engine," not "motor." :D

In mechanical engineering, a machine that converts the chemical energy of fuel into kinetic energy is called an engine or prime mover. A machine that converts potential energy to kinetic energy is called a motor.
Thanks for that. All too many refer to the engine in an automobile as a "motor" (which would be correct for electric automobiles). Likely due to the line that got fuzzed long ago when motorcycles were invented. It's a little more comfortable to say than enginecycle. :-)

H
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