First let me apologize for using a different user name to reply to your question, definitely don't want to confuse anyone trying to help me. My reason for having two ID's is complicated, but anyways...

Secondly, I was too busy today to draw a Schematic, maybe later tonight.

I did a search on eBay using "manual directional control valve" as keywords, and returned quite a few results mostly to do with instruction, either by CD, or Books.
At least one I will have to buy, because I don't know what {"Spool has P to T, and closed A and B ports at neutral."} means, likely if I bought a new valve the ports may be labeled. But I'd probably go with used.

The first item I looked at on eBay that wasn't a book was a valve that I don't think is what I need, the Valve weighs 125 pounds, LOL.
I'll keep looking...

For safety sake I will be buying an instructional Book, or CD before I blow myself up with too much pressure, or something. :-)

My project will have a hydraulic/mechanical brake (like a motorcycle/car), my question was how violently would the bike decelerate if the valve is "Closed".

I'm sure you've heard of the term "Engine Braking" on normal stick shift vehicles (some automatics), where you stop feeding the engine fuel, but the vehicle's momentum keeps the revs of the engine going a bit through the transmission until the drag of the engine slows the vehicle.
Very noticeable on my Motorcycle, if I am doing 70 on the interstate, and let go of the throttle, the Bike slows down as I watch the tachometer slowly drop, if I pull in the clutch, the Bike slows down less gradually, and the Engine immediately drops to an idle on the Tach. If I were to dump a gallon of water into the Carburetors while I was doing 70, guess what would happen, the cylinders of my Engine would "Hydraulic" causing catastrophic results, the Engine would stop spinning immediately, possibly breaking internal parts (likely), and if the Engine isn't turning the tranny would stop, the rear would stop, and I would be sliding uncontrollably down the highway.

THAT is exactly why I asked, what happens when you stop pressure to the Hydraulic motor suddenly?

As I have stated I have some experience with machinery using Rams, but not hyd. motors.
Our exhaust Pipe Bender for example, the valves that actuate the Rams go both ways, to either bend, or release the exhaust tubing, I didn't look at them today, but I believe they have one intake port, then two outputs to opposite ends of the ram Ram. Those valves STOP in the middle, and the Ram stops, and it would take an Enormous Force on the Ram to move it even a fraction of an inch until either the valve is opened, or a line is cut.

The Valves you've mentioned with a Neutral position, would those be different from the valves we use on our Pipe Bender?

A Truck lift we have for another example has an electric motor, that when turned on pressurizes the oil behind the Ram raising the lift, and up to 6 tons of payload. It has a one way valve in the line, then a manual release valve that slowly bleeds off pressure from the line while the load pushes the Ram back to it's starting point (where the rack meets the ground).

As for an accumulator, isn't that like the tank on an air compressor? The air tank gets pressurized to a point, then the motor shuts off, the air in the tank is potential energy, later used to drive air tools until the pressure in the tank reaches a point that turns on the motor till the pressure reach's the limit once again. In this example, the smaller the air tank, the more frequently the motor has to turn on.

So if a Hydraulic Motor circuit is analogous to an air compressor, I'm thinking, after the pump have a one-way valve in the line (like the truck lift has), then a tank (that can handle the pressures) for storing potential energy, then a valve that when opened sends some of that potential energy to the Hydraulic motor, which then turns the wheel, until the pressure drops too low, or the valve is shut.
At which point the valve had better have a "Neutral" position (if my definition of neutral is what you meant), or the impeller inside the hydraulic motor will stop spinning, and the rider will be flying over the handle bars.

I need a smoke, BBL.

AH, an expansion tank, like on a well-water pump, OF COURSE, BECAUSE IT'S A LIQUID, RATHER THAN A GAS!!!

DAMN, why didn't I think of that...
Thanks for that, it was an epiphany moment.

So if I use a tank, it should have room for a gas above the Hydraulic fluid, because the gas will compress much more than the oil does, allowing for more stored potential energy.
If I don't use a "Bladder" style, occasionally it would have to be drained of excess oil, correct?
Also any gas from the tank that escapes into the circuit, would simply make bubbles appear in the reservoir, correct? Maybe cause some noise to...

I also realized today while I was at the shop, we have an extra pressure washer lying about.

The pump on IT will pressurize oil as well as it does water, won't it?

Take a look at this web site to see what type pump you show in your photo.

You should be able to search for the company that made yours and find out its specs.

http://www.catpumps.com/pumps-...nger-sf-flushed.html

I tried that site, their pumps didn't look like the one I have, so I searched for "T991 Hydro pump" on the web, because of the # visible in the pic, and received this link in my search results:

http://www.shopetsonline.com/T991-p/bapl-1977.htm

I have a program called "ESBUnit Converter" on my computer which is just great for converting figures between US/Metric, and other conversions through all kinds of options, mass, volume, distance, area, & many more...

http://www.esbconsult.com/esbcalc/esbunitconv.htm

I used that program for a flow calculation, (on another thread I mention that I found specs on my HYD. Motor) the motor uses 9.6 cubic inches of fluid to turn 1 revolution:

GEOMETRIC DISPLACEMENT (CU. IN./REV.): 9.6 CU. IN. / REV

So if I am running @ 60 RPM on the motor, that is 9.6 CU. IN./per second, I put that in my calculator, it equates to 576.0000 CU in. per minute, or 2.4936 (US) Gallons per minute.

The Specs I found on the link above, says the output of the T991 pump is:
Maximum Volume: 4.0/3.5 GPM
Maximum Discharge Pressure: 1100/1500 PSI
Maximum Inlet Pressure: 125 PSI
Maximum Pump Speed: 1750/1450 RPM

I reverse calculated 3.5 GPM (the lower of the MAX figures), that equates to 16.1823 CU. Inches, per second/970.9409 CU inches per minute, which would make the Hyd. motor spin @ 101.14 RPM, right?

I believe the rear tire I have planned turns about 700 times to cover a mile, 700/101.14 RPM= 6.92 minutes to cover a mile, which only adds up to 8.7 MPH. Is that all I can expect?

The Hydraulic Motor is capable of so much more speed, but if the pump will only move up to 4 Gallons/minute is this the best I can expect for speed?
Or am I missing something in my Math...

By The Way, if you are wondering about the revs/mile figure on my rear tire, the Tire I have in mind is a 275/45R20, 29.8" Diameter, 699 Revolutions/mile.
I told you my design would be unique.

I am going to make that schematic of my design I promised a couple days ago, will be back later.

It would be less weight than my Father's Harley, which tips the scales around 500 pounds.

quote:

The Hydraulic Motor is capable of so much more speed, but if the pump will only move up to 4 Gallons/minute is this the best I can expect for speed?
Or am I missing something in my Math...

I actually come up with 84 RPM at 3.5 GPM, 96 RPM at 4 GPM. So you are close. I could not follow your nubers so I used the ones in the formula section on my basic book. I've used these Formula for years with no problem.

You will be disappointed with your setup if it will even takeoff without help. It will be a learning curve for you and unfortunately it is the way most persons learn hydraulic design. It'snot all bad since I have gleaned some unique ideas from the untrained since they've done things that I woulnt try since I know they wont work.

You need a Variable Volume Piston Pump to do the job right.However they are expensive unless you could find one at a junk yard. Cessna Hydraulics makes an aluminum body one that I've used on several home made units. One was for a 4 wheel tug used for towing a Lear Jet in and out of its hangar. Was'nt fast but real torquey.

These drawings should convey most of the design characteristics I have in mind.

The drawings are not intended to be drawn to scale, these are rough drafts.

Any of the items regarding Hydrostatic drive, are still in the planning stage.

Planned supplies for the frame, include 1.25" X .180W Dom tubing, and 4" X 6" X 0.25W box steel, which I have in ample supply.

Rear Wheel is 20" X 8" drilled with two bolt patterns 4.5" X 5 lug & 4.75" X 5 lug, Tire 275/45-20.

Engine 5.5HP OHV ICE.

Front Wheel, to be determined.
Pump, to be determined...
Valve, " "
Accumulator, " "

Reservoir, any 3-5 Gallon motorcycle gas tank I find, then modify lower ports. Moveable, for filling Engine's fuel tank, or a big notch cut to allow access.



Any Questions?

Maglub, I am going by the numbers for flow from the site I included with my post.

Bud T, after I went through doing the calculations using the ESB unit converter, I went to another members forum, where he provides a Calculator, where I also came up with 84.2 RPM @ 3.5 GPM.

As for take off power, with 1500 PSI, and low RPM won't it be torquey? if a bit slow...

700/84.2 RPM, would be 8.31 minutes to cover a mile, or 7.22MPH, woohoo. lol


Bud T, something you mentioned 2/18:
"A Power Steering Pump on most Automobiles is aroud 5-6 GPM at Engine Idle around 600 RPM and increases as RPM increases. That means your 3600 RPM Gas Engine direct driving the pump will produce about 30 GPM and your 5 HP Engine can raise that 30 GPM to about 400 PSI."

On the Converter provided in this forum:
http://forums.hydraulicspneuma...251087813#1251087813

Speed:
30GPM/9.6cu. in. = 721.875 RPM "WOW"
Torque:
9.6 displacement, 400 PSI = 611.464 in/lbs

Maybe I should go back to the idea of using an automotive Power Steering Pump...

About two months ago I scraped a real beauty of a pump from a Mercedes Turbo Diesel, the whole housing was Aluminum {that's why I recycled it} with a lid that would have been easily sealed, it was BEAUTIFUL, and weighed about 12 pounds before I stripped the guts out of it.



P.S. I hope my schematic is helpful.

A composite picture of something I saw today at a Swap meet/car show in Zephyrhills, FL.

A link to a folder with all of the pics I took today:
http://s167.photobucket.com/al.../Cyberfool1/2-22-09/

quote:

Originally posted by R Deinla:
But you have to limit the prime mover speed to rated, to avoid pump cavitation. But there are pumps that can be operated to higher RPM... just a few for special purpose. In this case your pump will be smaller but retains the capability to sustain more pressure.

For just a toy, I think steering pumps can do the job... but only for fewer time usage. You have to consider heat losses when using an open loop hydraulic system.

Heat losses? I have a smaller cooler that can handle the pressures of the Power Steering pump.

But tell me more about cavitation, is that a result of spinning the pump faster than it was intended? Does this result in aeration of the Hyd. fluid?, or the "hydraulic whine"?

As for over-winding... (example) An '89 Ford LTD I am going to cut up soon has a 302 V8 engine. The Power Steering pump on it has a Pulley on it that is as big, or bigger than the Pulley on the Crankshaft. Which would mean it spins as fast, or a little slower than the Engine. The Ford V8 is capable of far more RPM than the 5.5HP horizontal shaft engine is capable of, so unless I "Overdrive" the pulley ratio, the pump should hold up to quite a bit of abuse. Even if the pressures it creates are less than ideal, I need Volume.



Also can you give me an example of a closed loop Hydraulic system?
Our Pipe Bender, & Lift are also what I think of as open loop, because they both have a zero-pressure reservoir holding the bulk of the Oil. Or am I defining it wrong?

This message has been edited. Last edited by: Cyberfool,

A Dentist? LOL

So, I need decarbonated oil, gotcha...

You can read my explanation/understanding of Cavitation applied to hydraulic pumps starting on page 8-19 in the Basic Ebook. You can get to the Ebook from the Home Page of this Forum.

Both kinds of Cavitation should be avoided at the Inlet of any Hydraulic Pump unless short pump life can be tolerated.

Hey Bud, I'm gonna start reading the ebooks tonight, but I wanted to run something by you...

I was looking at the specs on a Wagner Marine Power steering pump, and it's displacement was 9.8 CU IN/rev, do you think that would be ideal to work in concert with my Motor which has a displacement of 9.6/rev?

Or would it be better to work with a smaller displacement pump that my small Engine can spin at 2-3 times faster than the desired RPM's of the Hyd. Motor?

My thinking is that the higher displacement pump would match the Motor well, but the demands on the Gas Engine would be too great.

OK, I'm off to read the ebooks.

A general rule of thumb for HP to drive a hydraulic pump is, "1 GPM can be elevated to 1,500 PSI by 1 HP input."
Therefore your 5 HP Engine would only be able to produce 5 GPM flow AT BEST. The rule of thumb above is based on 3 Phase Electric Motors and no Gas Enginge can compare.

Also, your 9.6 CIR (Cubic Inch per Revolution) Pump driven by a 3,600 RPM Gas Engine would have a Flow of, 9.6 CIR*3,600 RPM/231 (Cubic Inches per Gallon or almost 150 GPM.

If you drove the pump at 1 RPM it would theoretically drive the motor at 1 RPM+ and so on. Actually a Gear Pump and Motor may have enough ineffficencies that the pump would have to be turning at 4-6 RPM before the motor go up to 1 RPM and that is at no load. Add load and internal bypass of both units increases with increased pressure.

What you are attempting is going to require full HP no matter the speed your motor turns at any required pressure and if you are not continually at full Hydraulic Motor RPM, FULL SPEED OF THE VEHILE) you will be generating a lot of heat with the wasted energy. That is why any good Hydraulic Motor circuit for variable speed uses a Variable Flow Pump to conserve energy and operate at lower HP in the lower speeds.

The Military HUMVEE I posted a link to uses a Hydro-Static pump and Flow Dividers to allow it to run at 50 MPH and also be able to tow a Chinook Helicoter up a ramp into a cargo plane for transport over long distances. It uses an Eaton Hydro-Static pump to accomplish the speed changes.

There is no magic to Hydraulic Drives. They follow the same rules of any method of passing on energy. Hence the reason for multi speed transmissions of some sort in all vehicles.

Keep reading the basic book and you can see some circuits for Hydraulic Motor drives in the basic book. The circuits book has many more Hydro-Static circuits as well.