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Thread: Power steering pump to run shop hydraulics

  1. #11
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    I forget which model exactly,but some 90's model GM products had remote reservoirs.They also had relief valves with a simple die spring to set the pressure,add a few flatwashers under the spring for more pressure.

    I have often thought of adding a PS power unit to our 50ton Dake press at work.Not for actual press pressure,but as a fast ram travel.

    I did take a Ford PS pump and marry it to a Chevy starter once for a cheap 12vdc power pack.Worked great for a simple power up single acting application.
    I just need one more tool,just one!

  2. #12
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    Sep 2004
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    A buddy of mine built a ~50 ton press with GM power steering pump. He has a hand operated pump T-ed in somehow for jobs requiring 1200-3000psi. Steering pump is sufficient for most jobs, and saves lots of cranking.

    You will need a spool valve, and the extra reservior should be no taller than the pump. Use length and width to get your volume.

    Neglecting oil heating, minimum reservior volume can be the difference between max and min cylinder volume. (Rod extended/Rod retracted)

  3. #13
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    Actually I have built several wood splitters using Saginaw power steering pumps and they do a commendable job. Pressure capability is more than adequate 850-1600 psi as it comes out of the car or truck. Small car=lower pressure, bigger truck=more pressure and more volume. The built in pressure reliefs can be bypassed.

    I believe the Saginaw pumps, as in bobw53's photo, came in two displacements, .94 cu in per revolution and 1.06 cu in per revolution so you'll have to do the math for whatever you plan to power with it as far as required HP, speed or flow required.
    I know on some of the splitters I built, a 5 HP B&S had it's belly dragging the ground in order to drive it so it can suck up a bit of power fast. This was while pushing a 3.5" bore cylinder at about 1500 psi. This works out to about 14,000 lbs output force.
    Older cars would slow the engine down while cranking the wheel, newer ones have a switch that senses pressure and sends a signal to the ECM to increase idle speed.

    Flow is easily controlled with any one of many types of control valves and don't worry about the tiny reservoir as that is probably the least of your worries. Whatever size you need whether it's 1/2 pt. or 500 gallons is entirely up to you.

    Have fun hydraulics are fun and oh so versatile.

  4. #14
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    Quote Originally Posted by Don Young
    ........ A power steering pump is positive displacement, meaning that when it is running the oilflow is continuous at a certain rate..........
    Automotive power steering pumps are considered non positive displacement pumps because they will bypass internally when flow is stopped, such as when turning the wheels to the stops.

    A positive displacement pump essentially has no relief valve and relies on the system to integrate pressure relief valves.

    I realize this is splitting hairs though. As far as I'm concerned a vane or piston pump is positive displacement and a centrifugal pump would not be considered such...by me at least...but then I didn't write the book.

  5. #15
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    Quote Originally Posted by 1-800miner
    kind of on the same note..
    I have often thought of using a car differential.Apply power at the drive shaft,mount a high volume pump on one axle and a high pressure on the other.plumb them together.
    You get high volume with automatic transfer over to high pressure.
    It would not work unless you welded up the differential solid.

    But why, the power of turning the diff would suck a lot of power and it would also over complicate the process.

    Hydraulic pumps are available that put out high volume at low pressure and switch over to high pressure low volume depending on system loads and requirements. The beauty of these pumps is they do all of this transparently with a small footprint to boot.

  6. #16
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    Apr 2005
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    Quote Originally Posted by Willy
    Automotive power steering pumps are considered non positive displacement pumps because they will bypass internally when flow is stopped, such as when turning the wheels to the stops.

    A positive displacement pump essentially has no relief valve and relies on the system to integrate pressure relief valves.

    I realize this is splitting hairs though. As far as I'm concerned a vane or piston pump is positive displacement and a centrifugal pump would not be considered such...by me at least...but then I didn't write the book.
    Pure, 100% BS. A positive displacement pump moves a set volume (displacement) per revolution. A built in relief valve means nothing. It could be altered/ reset for any pressure, including enough to burst the pump.
    The relief valve is the relief valve , regardless of where it is located. The pump is the pump, regardless of where the relief valve is.

    "I realize this is splitting hairs though. As far as I'm concerned a vane or piston pump is positive displacement and a centrifugal pump would not be considered such...by me at least...but then I didn't write the book."

    Correct. A centrifugal pump is not positive displacement. A vane, gear, gerotor, or piston/plunger pump IS positive displacement, regardless of weather the relief valve is in the same casting or 100 miles away.
    Steering pumps have their relief valve incorporated in the casting for convenience and cheap construction. It does not change the characteristics of the pump.
    When a steering system is at the extreme right or left the relief valve is open. When a 10,000PSI cylinder is fully extended the relief valve is open. No difference unless the relief valve is improperly set, thus either pump failure or explosion .
    Last edited by tdmidget; 01-27-2011 at 09:46 AM.

  7. #17
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    I stand corrected.
    I have an old book on hydraulics that I took exception to.

    This is why I stated that I was not comfortable with it either.
    After a looking at a somewhat more reliable reference the distinction between pump types is all the more clear and reaffirms my prior feelings were correct.

    Oops, I see tdmidget beat me to the punch.

  8. #18
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    Going back to the OP. Hydraulic jacks use some very high pressures.

    A few guzintas for a 20 T jack with a +/- 2.25" diameter ram means 40,000 # push from just under 4 sq in area. That means 10,000 psi hydraulic pressure. Power steering pumps are nowhere near that high in pressure.

    Still for lower pressure appications they'd be a cheap source of a pump. I'm kinda spoiled because I have access to several all-in-one units from ag equipment. Their issue is low operating pressure too. Free pumps mean I can afford bigger cylinders for my projects if I can't find 'em out of the "inventory" piles.
    Crap by any other name is still crap.

  9. #19
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    Jan 2010
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    Virginia Beach, VA
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    Quote Originally Posted by wierdscience
    I forget which model exactly,but some 90's model GM products had remote reservoirs.They also had relief valves with a simple die spring to set the pressure,add a few flatwashers under the spring for more pressure.
    91 Sunbird has a remote reservoir as well as some 60's Fords. I changed out the single unit on my 65 Tbird to a remote reservoir I got from a 63 Tbird.

  10. #20
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    Sep 2009
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    NW Illinois USA
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    Chevy trucks around the late '60s had remote reservoirs.

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