3Hp hydraulic power unit

[Frank S]

Actually this would fall under the sub forum tools in progress but I think that one is gone.
After building my plate roller rather than press it straight into service I decided that I wanted to power it hydraulically.
This meant that I either had to dig through 10 tons of stuff still stashed away in 1 of my storage trailers to try and find where I had put my power unit or build another.
To build another was the easier choice First I started with an old automotive lift power unit off of a larger lift actually it was one I had removed from an elevator I built 20 years ago when the coupling went bad a few years back.
I made a new pump to motor coupling "see Pump/ motor shaft coupling
Then I inspected several pumps that I had and checked the motor, then located a 4 way valve the one I decided to use is a 3 bank valve I will cap 2 of the sections for now but may need them when I use this power unit to test other equipment.
next was to decide on a tank the 6 gallon plastic tank didn't fit my design criteria, so I settled on a 15 gallon steel drum it has a good diameter to height ratio being almost the same in height as in diameter.
I couldn't just mount the pump and motor directly to the top as the metal was too thin for my liking so I cut 3 old truck mud flaps to fill the depression in the top Then I needed to cut a round plate to cover these with and bolt through everything.
this was why I made the Simple plasma torch circle guide to cut out the round piece
here are some assembly pictures I still need to make up 3 hoses tomorrow if I have the correct fittings then will have to wait until I need to make a trip to town to get the oil.

[DIYer]

Thanks Frank S! We've added your Hydraulic Power Unit to our Metalworking category,
as well as to your builder page: Frank S's Homemade Tools. Your receipt:

Hydraulic Power Unit by Frank S

tags: roller, hydraulic, pump

[Crusty]

Your scrap pile(s) must be awesome Frank.

[Frank S]

Your scrap pile(s) must be awesome Frank.

Better than average, but I need to start attending auctions again because much of the stuff is dwindling

[Crusty]

I just scored a welding stool and a wide two drawer horizontal filing cabinet to hold my welding accessories by watching the Craigslist free section. Got some red steel and some stainless steel earlier in the year the same way. You gotta get there quick after it's posted and don't bother if it's out on the curb because it will be gone by the time you get there.

[metric_taper]

So what sort of hydraulic motor is on your plate roller? I assume that is what will be powered via this pump assembly. I'm not familiar with the pump your using, is that a spool valve manifold contraption, with a gear pump?

[Frank S]

So what sort of hydraulic motor is on your plate roller? I assume that is what will be powered via this pump assembly. I'm not familiar with the pump your using, is that a spool valve manifold contraption, with a gear pump?

The pump is gear 0.6 cubic inch per revolution or 2.1 gal per minute at 2800 RPM the block between the pump and motor has an internal relief valve factory set at 4000 PSI
The bank valve is a spool valve with relief sat to 3000 PSI by changing out a single plug it can be used as power beyond with other valves. I have several dozen 4 way poppet solenoid valves with 12 vdc coils but I didn't have a suitable body to mount some of them in and no good way to create a cavity cutter or a burnishing tool Ideally this would have been the preferred way to have built it as everything would have been more clean and compact. If I had the cavity cutters I could have made a mono block containing all passages and mounted the pump and motor directly to it. As it is this spool valve set up is way oversized but I'm not going to worry about it.
the motor on the plate roll is a Parker wheel motor 2.5 cubic inches @ 2750 PSi it has 832 in.lb. torque @ 1 gallon per minute The minimum flow for it is 1/2 gallon per min. the max is 11 gallon per minute max torque @ max flow would be 838 in. lb but it would also be truning at 897 PRM
The plate roll has a 10 to 1 speed reduction which should yield 693 ft. lbs of torque to the rolls except for the obvious losses due to internal leakage of the oversized spool valve plus other accumulated losses IE low flow rate through the motor the pump not being new and so forth I figure there could possibly be a 25 to 30% loss of efficiency if I wind up with 400 ft lbs I'll be more than happy. But I may find that the target main roll RPM of 5 will turn out to be much higher than that even with such a diminutive sized power unit if this is the case I will have to either feather the spool valve or add a flow restrictor or I could up the reduction by adding a second shaft and sprocket system if need be.
I should find out in a couple of days when Bob pays me for mounting the APU on his truck.

[MeJasonT]

Frank,
I have a pressure washer with the a 3 stage pump with a relief set for 4000 psi , I wonder if it would make a suitable hydraulic unit for me. simply swapping out the medium from water to hydraulic oil ?

[Frank S]

Frank,
I have a pressure washer with the a 3 stage pump with a relief set for 4000 psi , I wonder if it would make a suitable hydraulic unit for me. simply swapping out the medium from water to hydraulic oil ?

Ok let's take a closer look at what you have.
First off in theory any pump can be used to move different fluid mediums Note I said in theory for this is the important issue here.
centrifugal water pumps can move oils just as easy as moving water. the same goes for diaphragm pumps vane pumps and piston pumps.
using a pump specifically designed to move hydraulic oils as a water pump will work but the service life would be limited to the lubrication factor.
But in your case you are going the other way round, replacing water as the medium being transferred to that of AWS32 or another grade of hydraulic oil.
What you have is a piston pump that has 3 pistons communally known as a triplex pump generically called a cat pump although cat pumps is a brand the name has become the catch phrase like coke for soda or AR15 style rifles.
if it in fact has multiple stages of flows and or pressures this would be accomplished via the design of the combination relief bypass valve through a series of differential spring rates and a free floating piston within a sleeve and a needle protruding through an orifice.
As long as the pressure doesn't rise above the design criteria of the pump it wont care whether it is moving water or oil as thick as molasses it will be the valves on both the suction and the pressure side of the pump that will be the determining factor as to whether or not the pump is going to last a minute a day or 10 years . The compatibility of the seals with oils will be another but should not be a problem in most cases unless they are made of a compound that oil will be absorbed in causing them to deteriorate this is unlikely to happen though. as these pumps are designed to also have detergents pass through them as well.
Lastly it comes down to a clearance issue in the valves even the thinnest of oils are thicker than water so a valve designed to allow say 5 gallons per minute to pass through might only have sufficient clearances to allow a much lower percentage of the higher viscosity oil to pass again most likely not going to be a problem particularly if the valves are poppet design.
So in my opinion I would say go for it with one word of caution expect the relief valve to fail unless you can reduce the pressure to a lower setting.
I have several of those pumps like the one you pictured that are belt driven someday I might connect one to a gasoline engine for a larger power unit myself just to prove my theory.

[MeJasonT]

Still researching
pressure washer as hydraulic pump
I'm currently pondering two conclusions
The seals thing is a myth. The o rings and seals are more than likely all viton (rockwell 80 hardness)which will be identical to most hydraulics and cylinders i,ve ever come across - its not as if they are irreplaceable.
However as you/Frank quite rightly pointed out is probably the wrong sort of pump, based on the information in the above link the pressure is dictated by the orifice and not the pumps ability to provide the volume and pressure. Oh well Water jet cutter it is then. just need a pressure amplifier and ceramic/ruby nozzles now.

https://hackaday.com/2017/05/31/a-wa...essure-washer/